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Zebra is a routing software package that provides TCP/IP based routing services with routing protocols support such as RIPv1, RIPv2, RIPng, OSPFv2, OSPFv3, BGP-4, and BGP-4+ (see section 1.4 Supported RFC). Zebra also supports special BGP Route Reflector and Route Server behavior. In addition to traditional IPv4 routing protocols, Zebra also supports IPv6 routing protocols. With SNMP daemon which supports SMUX protocol, Zebra provides routing protocol MIBs (see section 15. SNMP Support).
Zebra uses an advanced software architecture to provide you with a high quality, multi server routing engine. Zebra has an interactive user interface for each routing protocol and supports common client commands. Due to this design, you can add new protocol daemons to Zebra easily. You can use Zebra library as your program's client user interface.
Zebra is an official GNU software and distributed under the GNU General Public License.
1.1 About Zebra Basic information about Zebra 1.2 System Architecture The Zebra system architecture 1.3 Supported Platforms Supported platforms and future plans 1.4 Supported RFC Supported RFCs 1.5 How to get Zebra 1.6 Mailing List Mailing list information 1.7 Bug Reports Mail address for bug data
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Today, TCP/IP networks are covering all of the world. The Internet has been deployed in many countries, companies, and to the home. When you connect to the Internet your packet will pass many routers which have TCP/IP routing functionality.
A system with Zebra installed acts as a dedicated router. With Zebra, your machine exchanges routing information with other routers using routing protocols. Zebra uses this information to update the kernel routing table so that the right data goes to the right place. You can dynamically change the configuration and you may view routing table information from the Zebra terminal interface.
Adding to routing protocol support, Zebra can setup interface's flags, interface's address, static routes and so on. If you have a small network, or a stub network, or xDSL connection, configuring the Zebra routing software is very easy. The only thing you have to do is to set up the interfaces and put a few commands about static routes and/or default routes. If the network is rather large, or if the network structure changes frequently, you will want to take advantage of Zebra's dynamic routing protocol support for protocols such as RIP, OSPF or BGP. Zebra is with you.
Traditionally, UNIX based router configuration is done by
ifconfig
and route
commands. Status of routing
table is displayed by netstat
utility. Almost of these
commands work only if the user has root privileges. Zebra has a different
system administration method. There are two user modes in Zebra. One is
normal mode, the other is enable mode. Normal mode user can only view
system status, enable mode user can change system configuration. This
UNIX account independent feature will be great help to the router
administrator.
Currently, Zebra supports common unicast routing protocols. Multicast routing protocols such as BGMP, PIM-SM, PIM-DM will be supported in Zebra 2.0. MPLS support is going on. In the future, TCP/IP filtering control, QoS control, diffserv configuration will be added to Zebra. Zebra project's final goal is making a productive, quality free TCP/IP routing software.
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Traditional routing software is made as a one process program which provides all of the routing protocol functionalities. Zebra takes a different approach. It is made from a collection of several daemons that work together to build the routing table. There may be several protocol-specific routing daemons and zebra the kernel routing manager.
The ripd
daemon handles the RIP protocol, while
ospfd
is a daemon which supports OSPF version 2.
bgpd
supports the BGP-4 protocol. For changing the kernel
routing table and for redistribution of routes between different routing
protocols, there is a kernel routing table manager zebra
daemon. It is easy to add a new routing protocol daemons to the entire
routing system without affecting any other software. You need to run only
the protocol daemon associated with routing protocols in use. Thus,
user may run a specific daemon and send routing reports to a central
routing console.
There is no need for these daemons to be running on the same machine. You can even run several same protocol daemons on the same machine. This architecture creates new possibilities for the routing system.
+----+ +----+ +-----+ +-----+ |bgpd| |ripd| |ospfd| |zebra| +----+ +----+ +-----+ +-----+ | +---------------------------|--+ | v | | UNIX Kernel routing table | | | +------------------------------+ Zebra System Architecture |
Multi-process architecture brings extensibility, modularity and
maintainability. At the same time it also brings many configuration
files and terminal interfaces. Each daemon has it's own configuration
file and terminal interface. When you configure a static route, it must
be done in zebra
configuration file. When you configure BGP
network it must be done in bgpd
configuration file. This can be a
very annoying thing. To resolve the problem, Zebra provides integrated
user interface shell called vtysh
. vtysh
connects to
each daemon with UNIX domain socket and then works as a proxy for user input.
Zebra was planned to use multi-threaded mechanism when it runs with a
kernel that supports multi-threads. But at the moment, the thread
library which comes with GNU/Linux or FreeBSD has some problems with
running reliable services such as routing software, so we don't use
threads at all. Instead we use the select(2)
system call for
multiplexing the events.
When zebra
runs under a GNU Hurd kernel it will act as a
kernel routing table itself. Under GNU Hurd, all TCP/IP services are
provided by user processes called pfinet
. Zebra will provide
all the routing selection mechanisms for the process. This feature will
be implemented when GNU Hurd becomes stable.
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Currently Zebra supports GNU/Linux, BSD and Solaris. Below is a list
of OS versions on which Zebra runs. Porting Zebra to other platforms is
not so too difficult. Platform dependent codes exist only in
zebra
daemon. Protocol daemons are platform independent.
Please let us know when you find out Zebra runs on a platform which is not
listed below.
Some IPv6 stacks are in development. Zebra supports following IPv6 stacks. For BSD, we recommend KAME IPv6 stack. Solaris IPv6 stack is not yet supported.
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Below is the list of currently supported RFC's.
When SNMP support is enabled, below RFC is also supported.
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Zebra is still beta software and there is no officially released version. So currently Zebra is distributed from Zebra beta ftp site located at:
Once Zebra is released you can get it from GNU FTP site and its mirror sites. We are planning Zebra-1.0 as the first released version.
Zebra's official web page is located at:
http://www.gnu.org/software/zebra/zebra.html.
There is a Zebra beta tester web page at:
You can get the latest beta software information from this page.
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There is a mailing list for discussions about Zebra. If you have any comments or suggestions to Zebra, please send mail to zebra@zebra.org. New snapshot announcements, improvement notes, and patches are sent to the list.
To subscribe to the Zebra mailing list, please send a mail to majordomo@zebra.org with a message body that includes only:
subscribe zebra
To unsubscribe from the list, please send a mail to majordomo@zebra.org with a message body that includes only:
unsubscribe zebra
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If you think you have found a bug, please send a bug report to bug-zebra@gnu.org. When you send a bug report, please be careful about the points below.
netstat -rn
and ifconfig -a
.
Information from zebra's VTY command show ip route
will also be
helpful.
Bug reports are very important for us to improve the quality of Zebra. Zebra is still in the development stage, but please don't hesitate to send a bug report to bug-zebra@gnu.org.
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There are three steps for installing the software: configuration, compilation, and installation.
2.1 Configure the Software 2.2 Build the Software 2.3 Install the Software
The easiest way to get Zebra running is to issue the following commands:
% configure % make % make install |
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Zebra has an excellent configure script which automatically detects most host configurations. There are several additional configure options you can use to turn off IPv6 support, to disable the compilation of specific daemons, and to enable SNMP support.
bgpd
which does not make bgp announcements at all. This
feature is good for using bgpd
as a BGP announcement listener.
You may specify any combination of the above options to the configure script. By default, the executables are placed in `/usr/local/sbin' and the configuration files in `/usr/local/etc'. The `/usr/local/' installation prefix and other directories may be changed using the following options to the configuration script.
% ./configure --disable-ipv6 |
This command will configure zebra and the routing daemons.
There are several options available only to GNU/Linux systems: (1).
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After configuring the software, you will need to compile it for your
system. Simply issue the command make
in the root of the source
directory and the software will be compiled. If you have *any* problems
at this stage, be certain to send a bug report See section 1.7 Bug Reports.
% ./configure . . . ./configure output . . . % make |
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Installing the software to your system consists of copying the compiled programs and supporting files to a standard location. After the installation process has completed, these files have been copied from your work directory to `/usr/local/bin', and `/usr/local/etc'.
To install the Zebra suite, issue the following command at your shell
prompt: make install
.
% % make install % |
Zebra daemons have their own terminal interface or VTY. After installation, you have to setup each beast's port number to connect to them. Please add the following entries to `/etc/services'.
zebrasrv 2600/tcp # zebra service zebra 2601/tcp # zebra vty ripd 2602/tcp # RIPd vty ripngd 2603/tcp # RIPngd vty ospfd 2604/tcp # OSPFd vty bgpd 2605/tcp # BGPd vty ospf6d 2606/tcp # OSPF6d vty |
If you use a FreeBSD newer than 2.2.8, the above entries are already added to `/etc/services' so there is no need to add it. If you specify a port number when starting the daemon, these entries may not be needed.
You may need to make changes to the config files in `/usr/local/etc/*.conf'. See section 3.1 Config Commands.
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There are five routing daemons in use, and there is one manager daemon. These daemons may be located on separate machines from the manager daemon. Each of these daemons will listen on a particular port for incoming VTY connections. The routing daemons are:
ripd
, ripngd
, ospfd
, ospf6d
, bgpd
zebra
The following sections discuss commands common to all the routing daemons.
3.1 Config Commands Commands used in config files 3.2 Common Invocation Options Starting the daemons 3.3 Virtual Terminal Interfaces Interacting with the daemons
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3.1.1 Basic Config Commands Some of the generic config commands 3.1.2 Sample Config File An example config file
In a config file, you can write the debugging options, a vty's password, routing daemon configurations, a log file name, and so forth. This information forms the initial command set for a routing beast as it is starting.
Config files are generally found in:
Each of the daemons has its own config file. For example, zebra's default config file name is:
The daemon name plus `.conf' is the default config file name. You can specify a config file using the -f or --config-file options when starting the daemon.
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filename
as
follows.
log file /usr/local/etc/bgpd.log |
exec-timeout 0 0
.
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Below is a sample configuration file for the zebra daemon.
! ! Zebra configuration file ! hostname Router password zebra enable password zebra ! log stdout ! ! |
'!' and '#' are comment characters. If the first character of the word is one of the comment characters then from the rest of the line forward will be ignored as a comment.
password zebra!password |
If a comment character is not the first character of the word, it's a normal character. So in the above example '!' will not be regarded as a comment and the password is set to 'zebra!password'.
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These options apply to all Zebra daemons.
Upon startup the process identifier of the daemon is written to a file,
typically in `/var/run'. This file can be used by the init system
to implement commands such as .../init.d/zebra status
,
.../init.d/zebra restart
or .../init.d/zebra
stop
.
The file name is an run-time option rather than a configure-time option so that multiple routing daemons can be run simultaneously. This is useful when using Zebra to implement a routing looking glass. One machine can be used to collect differing routing views from differing points in the network.
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VTY -- Virtual Terminal [aka TeletYpe] Interface is a command line interface (CLI) for user interaction with the routing daemon.
3.3.1 VTY Overview Basics about VTYs 3.3.2 VTY Modes View, Enable, and Other VTY modes 3.3.3 VTY CLI Commands Commands for movement, edition, and management
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VTY stands for Virtual TeletYpe interface. It means you can connect to the daemon via the telnet protocol.
To enable a VTY interface, you have to setup a VTY password. If there is no VTY password, one cannot connect to the VTY interface at all.
% telnet localhost 2601 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Hello, this is zebra (version 0.93) Copyright 1997-2000 Kunihiro Ishiguro User Access Verification Password: XXXXX Router> ? enable Turn on privileged commands exit Exit current mode and down to previous mode help Description of the interactive help system list Print command list show Show running system information who Display who is on a vty Router> enable Password: XXXXX Router# configure terminal Router(config)# interface eth0 Router(config-if)# ip address 10.0.0.1/8 Router(config-if)# ^Z Router# |
'?' is very useful for looking up commands.
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There are three basic VTY modes:
3.3.2.1 VTY View Mode Mode for read-only interaction 3.3.2.2 VTY Enable Mode Mode for read-write interaction 3.3.2.3 VTY Other Modes Special modes (tftp, etc)
There are commands that may be restricted to specific VTY modes.
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This mode is for read-only access to the CLI. One may exit the mode by
leaving the system, or by entering enable
mode.
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This mode is for read-write access to the CLI. One may exit the mode by leaving the system, or by escaping to view mode.
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This page is for describing other modes.
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Commands that you may use at the command-line are described in the following three subsubsections.
3.3.3.1 CLI Movement Commands Commands for moving the cursor about 3.3.3.2 CLI Editing Commands Commands for changing text 3.3.3.3 CLI Advanced Commands Other commands, session management and so on
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These commands are used for moving the CLI cursor. The C character means press the Control Key.
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These commands are used for editing text on a line. The C character means press the Control Key.
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There are several additional CLI commands for command line completions, insta-help, and VTY session management.
help
at the beginning of
the line. Typing ? at any point in the line will show possible
completions.
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zebra
is an IP routing manager. It provides kernel routing
table updates, interface lookups, and redistribution of routes between
different routing protocols.
4.1 Invoking zebra Running the program 4.2 Interface Commands Commands for zebra interfaces 4.3 Static Route Commands Commands for adding static routes 4.4 zebra Terminal Mode Commands Commands for zebra's VTY
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Besides the common invocation options (see section 3.2 Common Invocation Options), the
zebra
specific invocation options are listed below.
zebra
parses configuration file and terminates
immediately.
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Static routing is a very fundamental feature of routing technology. It defines static prefix and gateway.
ip route 10.0.0.0/8 10.0.0.2 ip route 10.0.0.0/8 ppp0 |
First example defines 10.0.0.0/8 static route with gateway 10.0.0.2. Second one defines the same prefix but with gateway to interface ppp0.
ip route 10.0.0.0 255.255.255.0 10.0.0.2 ip route 10.0.0.0 255.255.255.0 ppp0 |
This is a same setting using this statement.
Multiple nexthop static route
ip route 10.0.0.1/32 10.0.0.2 ip route 10.0.0.1/32 10.0.0.3 ip route 10.0.0.1/32 eth0 |
If there is no route to 10.0.0.2 and 10.0.0.3, and interface eth0 is reachable, then the last route is installed into the kernel.
zebra> show ip route S> 10.0.0.1/32 [1/0] via 10.0.0.2 inactive via 10.0.0.3 inactive * is directly connected, eth0 |
Floating static route
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Router# show ip route Codes: K - kernel route, C - connected, S - static, R - RIP, B - BGP * - FIB route. K* 0.0.0.0/0 203.181.89.241 S 0.0.0.0/0 203.181.89.1 C* 127.0.0.0/8 lo C* 203.181.89.240/28 eth0 |
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RIP -- Routing Information Protocol is widely deployed interior gateway protocol. RIP was developed in the 1970s at Xerox Labs as part of the XNS routing protocol. RIP is a distance-vector protocol and is based on the Bellman-Ford algorithms. As a distance-vector protocol, RIP router send updates to its neighbors periodically, thus allowing the convergence to a known topology. In each update, the distance to any given network will be broadcasted to its neighboring router.
ripd
supports RIP version 2 as described in RFC2453 and RIP
version 1 as described in RFC1058.
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The default configuration file name of ripd
's is
`ripd.conf'. When invocation ripd
searches directory
/usr/local/etc. If `ripd.conf' is not there next
search current directory.
RIP uses UDP port 521 to send and receive RIP packets. So the user must have
the capability to bind the port, generally this means that the user must
have superuser privileges. RIP protocol requires interface information
maintained by zebra
daemon. So running zebra
is mandatory to run ripd
. Thus minimum sequence for running
RIP is like below:
# zebra -d # ripd -d |
Please note that zebra
must be invoked before ripd
.
To stop ripd
. Please use kill `cat
/var/run/ripd.pid`
. Certain signals have special meaningss to ripd
.
ripd
logfile.
ripd
sweeps all installed RIP routes then terminates properly.
ripd
invocation options. Common options that can be specified
(see section 3.2 Common Invocation Options).
ripd
.
5.1.1 RIP netmask
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The netmask features of ripd
support both version 1 and version 2 of
RIP. Version 1 of RIP originally contained no netmask information. In
RIP version 1, network classes were originally used to determine the
size of the netmask. Class A networks use 8 bits of mask, Class B
networks use 16 bits of masks, while Class C networks use 24 bits of
mask. Today, the most widely used method of a network mask is assigned
to the packet on the basis of the interface that received the packet.
Version 2 of RIP supports a variable length subnet mask (VLSM). By
extending the subnet mask, the mask can be divided and reused. Each
subnet can be used for different purposes such as large to middle size
LANs and WAN links. Zebra ripd
does not support the non-sequential
netmasks that are included in RIP Version 2.
In a case of similar information with the same prefix and metric, the old information will be suppressed. Ripd does not currently support equal cost multipath routing.
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router rip
command is necessary to enable RIP. To disable
RIP, use the no router rip
command. RIP must be enabled before
carrying out any of the RIP commands.
RIP can be configured to process either Version 1 or Version 2 packets, the default mode is Version 2. If no version is specified, then the RIP daemon will default to Version 2. If RIP is set to Version 1, the setting "Version 1" will be displayed, but the setting "Version 2" will not be displayed whether or not Version 2 is set explicitly as the version of RIP being used.
This group of commands either enables or disables RIP interfaces between
certain numbers of a specified network address. For example, if the
network for 10.0.0.0/24 is RIP enabled, this would result in all the
addresses from 10.0.0.0 to 10.0.0.255 being enabled for RIP. The no
network
command will disable RIP for the specified network.
network ifname
command. The no network ifname
command will disable
RIP on the specified interface.
no
neighbor a.b.c.d
command will disable the RIP neighbor.
Below is very simple RIP configuration. Interface eth0
and
interface which address match to 10.0.0.0/8
are RIP enabled.
! router rip network 10.0.0.0/8 network eth0 ! |
Passive interface
neighbor
command.
RIP version handling
RIP split-horizon
ip
split-horizon
. If you don't perform split-horizon on the interface,
please specify no ip split-horizon
.
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redistribute kernel
redistributes routing information from
kernel route entries into the RIP tables. no redistribute kernel
disables the routes.
redistribute static
redistributes routing information from
static route entries into the RIP tables. no redistribute static
disables the routes.
no
redistribute connected
disables the connected routes in the RIP tables.
This command redistribute connected of the interface which RIP disabled.
The connected route on RIP enabled interface is announced by default.
redistribute ospf
redistributes routing information from
ospf route entries into the RIP tables. no redistribute ospf
disables the routes.
redistribute bgp
redistributes routing information from
bgp route entries into the RIP tables. no redistribute bgp
disables the routes.
If you want to specify RIP only static routes:
route
command makes a static
route only inside RIP. This command should be used only by advanced
users who are particularly knowledgeable about the RIP protocol. In
most cases, we recommend creating a static route in Zebra and
redistributing it in RIP using redistribute static
.
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RIP routes can be filtered by a distribute-list.
distribute-list
command. access_list is the access list name. direct is
`in' or `out'. If direct is `in' the access list
is applied to input packets.
The distribute-list
command can be used to filter the RIP path.
distribute-list
can apply access-lists to a chosen interface.
First, one should specify the access-list. Next, the name of the
access-list is used in the distribute-list command. For example, in the
following configuration `eth0' will permit only the paths that
match the route 10.0.0.0/8
! router rip distribute-list private in eth0 ! access-list private permit 10 10.0.0.0/8 access-list private deny any ! |
distribute-list
can be applied to both incoming and outgoing data.
distribute-list
command. prefix_list is the prefix list
name. Next is the direction of `in' or `out'. If
direct is `in' the access list is applied to input packets.
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RIP metric is a value for distance for the network. Usually
ripd
increment the metric when the network information is
received. Redistributed routes' metric is set to 1.
redistribute connected
. To modify
connected route's metric value, please use redistribute
connected metric
or route-map
. offset-list
also
affects connected routes.
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Distance value is used in zebra daemon. Default RIP distance is 120.
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Usage of ripd
's route-map support.
Optional argument route-map MAP_NAME can be added to each redistribute
statement.
redistribute static [route-map MAP_NAME] redistribute connected [route-map MAP_NAME] ..... |
Cisco applies route-map _before_ routes will exported to rip route
table. In current Zebra's test implementation, ripd
applies route-map
after routes are listed in the route table and before routes will be announced
to an interface (something like output filter). I think it is not so clear,
but it is draft and it may be changed at future.
Route-map statement (see section 12. Route Map) is needed to use route-map functionality.
ripd
IPv4 address. Match if
route has this next-hop (meaning next-hop listed in the rip route
table - "show ip rip")
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! key chain test key 1 key-string test ! interface eth1 ip rip authentication mode md5 ip rip authentication key-chain test ! |
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RIP protocol has several timers. User can configure those timers' values
by timers basic
command.
The default settings for the timers are as follows:
The timers basic
command allows the the default values of the timers
listed above to be changed.
no timers basic
command will reset the timers to the default
settings listed above.
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To display RIP routes.
The command displays all RIP routes. For routes that are received through RIP, this command will display the time the packet was sent and the tag information. This command will also display this information for routes redistributed into RIP.
ripd> show ip protocols Routing Protocol is "rip" Sending updates every 30 seconds with +/-50%, next due in 35 seconds Timeout after 180 seconds, garbage collect after 120 seconds Outgoing update filter list for all interface is not set Incoming update filter list for all interface is not set Default redistribution metric is 1 Redistributing: kernel connected Default version control: send version 2, receive version 2 Interface Send Recv Routing for Networks: eth0 eth1 1.1.1.1 203.181.89.241 Routing Information Sources: Gateway BadPackets BadRoutes Distance Last Update |
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Debug for RIP protocol.
debug rip
will show RIP events. Sending and receiving
packets, timers, and changes in interfaces are events shown with ripd
.
debug rip packet
will display detailed information about the RIP
packets. The origin and port number of the packet as well as a packet
dump is shown.
This command will show the communication between ripd
and zebra
. The
main information will include addition and deletion of paths to the
kernel and the sending and receiving of interface information.
ripd
's debugging option.
show debugging rip
will show all information currently set for ripd
debug.
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ripngd
supports the RIPng protocol as described in RFC2080. It's an
IPv6 reincarnation of the RIP protocol.
6.1 Invoking ripngd 6.2 ripngd Configuration 6.3 ripngd Terminal Mode Commands 6.4 ripngd Filtering Commands
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There are no ripngd
specific invocation options. Common options
can be specified (see section 3.2 Common Invocation Options).
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Currently ripngd supports the following commands:
zebra
daemon.
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distribute-list
command. access_list is an access-list
name. direct is `in' or `out'. If direct is
`in', the access-list is applied only to incoming packets.
distribute-list local-only out sit1 |
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OSPF version 2 is a routing protocol which described in RFC2328 - OSPF Version 2. OSPF is IGP (Interior Gateway Protocols). Compared with RIP, OSPF can provide scalable network support and faster convergence time. OSPF is widely used in large networks such as ISP backbone and enterprise networks.
7.1 Configuring ospfd 7.2 OSPF router 7.3 OSPF area 7.4 OSPF interface 7.5 Redistribute routes to OSPF 7.6 Showing OSPF information 7.7 Debugging OSPF
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There is no ospfd
specific options. Common options can be
specified (see section 3.2 Common Invocation Options) to ospfd
.
ospfd
needs interface information from zebra
. So
please make it sure zebra
is running before invoking
ospfd
.
Like other daemons, ospfd
configuration is done in OSPF
specific configuration file `ospfd.conf'.
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To start OSPF process you have to specify the OSPF router. As of this
writing, ospfd
does not support multiple OSPF processes.
ospfd
does not yet
support multiple OSPF processes. So you can not specify an OSPF process
number.
router ospf network 10.0.0.0/8 area 0 |
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ospf6d
is a daemon support OSPF version 3 for IPv6 network.
OSPF for IPv6 is described in RFC2740.
8.1 OSPF6 router 8.2 OSPF6 area 8.3 OSPF6 interface 8.4 Redistribute routes to OSPF6 8.5 Showing OSPF6 information
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Area support for OSPFv3 is not yet implemented.
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BGP stands for a Border Gateway Protocol. The lastest BGP version
is 4. It is referred as BGP-4. BGP-4 is one of the Exterior Gateway
Protocols and de-fact standard of Inter Domain routing protocol.
BGP-4 is described in RFC1771
- A Border Gateway Protocol
4 (BGP-4).
Many extentions are added to RFC1771
. RFC2858
-
Multiprotocol Extensions for BGP-4 provide multiprotocol
support to BGP-4.
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Default configuration file of bgpd
is `bgpd.conf'.
bgpd
searches the current directory first then
/usr/local/etc/bgpd.conf. All of bgpd's command must be
configured in `bgpd.conf'.
bgpd
specific invocation options are described below. Common
options may also be specified (see section 3.2 Common Invocation Options).
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First of all you must configure BGP router with router bgp
command. To configure BGP router, you need AS number. AS number is an
identification of autonomous system. BGP protocol uses the AS number
for detecting whether the BGP connection is internal one or external one.
BGP Commands
. You can not
create different BGP process under different asn without
specifying multiple-instance
(see section 9.13.1 Multiple instance).
bgpd
connects to zebra
it gets
interface and address information. In that case default router ID value
is selected as the largest IP Address of the interfaces. When
router zebra
is not enabled bgpd
can't get interface information
so router-id
is set to 0.0.0.0. So please set router-id by hand.
9.2.1 BGP distance 9.2.2 BGP decision process
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9.3.1 BGP route 9.3.2 Route Aggregation 9.3.3 Redistribute to BGP
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router bgp 1 network 10.0.0.0/8 |
bgp
doesn't care about IGP routes when announcing its routes.
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9.4.1 Defining Peer 9.4.2 BGP Peer commands 9.4.3 Peer filtering
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router bgp 1 neighbor 10.0.0.1 remote-as 2 |
This command must be the first command used when configuring a neighbor.
If the remote-as is not specified, bgpd
will complain like this:
can't find neighbor 10.0.0.1 |
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In a router bgp
clause there are neighbor specific configurations
required.
no neighbor peer remote-as as-number
but all
configuration of the neighbor will be deleted. When you want to
preserve the configuration, but want to drop the BGP peer, use this
syntax.
bgpd
's default is to not announce the default route (0.0.0.0/0) even it
is in routing table. When you want to announce default routes to the
peer, use this command.
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in
or
out
.
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AS (Autonomous System) is one of the essential element of BGP. BGP
is a distance vector routing protocol. AS framework provides distance
vector metric and loop detection to BGP. And also AS can provide
policy routing by AS path prepend. RFC1930
- Guidelines
for creation, selection, and registration of an Autonomous System
(AS) describes how to use AS.
AS number is tow octet. It's value range is from 1 to 65535. AS numbers 64512 through 65535 are defined as private AS numbers. Private AS numbers must not to be advertised in the global Internet.
9.7.1 AS Path Regular Expression 9.7.2 Display BGP Routes by AS Path 9.7.3 AS Path Access List 9.7.4 Using AS Path in Route Map 9.7.5 Private AS Numbers
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AS path regular expression can be used for displaying BGP routes and
AS path access list. AS path regular expression is based on
POSIX 1003.2
regular expressions. Following description is
just a subset of POSIX
regular expression. User can use full
POSIX
regular expression. Adding to that special character '_'
is added for AS path regular expression.
.
*
+
?
^
$
_
_
has special meanings in AS path regular expression.
It matches to space and comma , and AS set delimiter { and } and AS
confederation delimiter (
and )
. And it also matches to
the beginning of the line and the end of the line.
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To show BGP routes which has specific AS path information show
ip bgp
command can be used.
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AS path access list is user defined AS path.
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BGP communities attribute is widely used for implementing policy
routing. Network operators can manipulate BGP communities attribute
based on their network policy. BGP communities attribute is defined
in RFC1997
- BGP Communities Attribute and
RFC1998
- An Application of the BGP Community Attribute
in Multi-home Routing. It is an optional transitive attribute,
therefore local policy can travel through different autonomous system.
Communities attribute is a set of communities values. Each communities value is 4 octet long. The following format is used to define communities value.
AS:VAL
AS
is high
order 2 octet in digit format. VAL
is low order 2 octet in
digit format. This format is useful to define AS oriented policy
value. For example, 7675:80
can be used when AS 7675 wants to
pass local policy value 80 to neighboring peer.
internet
internet
represents well-known communities value 0.
no-export
no-export
represents well-known communities value NO_EXPORT
no-advertise
no-advertise
represents well-known communities value
NO_ADVERTISE
local-AS
local-AS
represents well-known communities value
NO_EXPORT_SUBCONFED
(0xFFFFFF03). All routes carry this
value must not be advertised to external BGP peers. Even if the
neighboring router is part of confederation, it is considered as
external BGP peer, so the route will not be announced to the peer.
When BGP communities attribute is received, duplicated communities value in the communities attribute is ignored and each communities values are sorted in numerical order.
9.8.1 BGP Community Lists 9.8.2 Numbered BGP Community Lists 9.8.3 BGP Community in Route Map 9.8.4 Display BGP Routes by Community 9.8.5 Using BGP Communities Attribute
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Community-list is a user defined BGP communites attribute list. Community-list can be used for matching or manipulating BGP communities attribute in BGP updates.
There are two types of community-list. One is standard community-list and another is expanded community-list. Standard community-list defines communities attribute. Expanded community-list defines communities attribute string with regular expression. Standard community-list is compiled into binary format when user define it. Standard community-list will be directly compared to BGP communities attribute in BGP updates. Therefore the comparison is faster than expanded community-list.
# show ip community-list Named Community standard list CLIST permit 7675:80 7675:100 no-export deny internet Named Community expanded list EXPAND permit : # show ip community-list CLIST Named Community standard list CLIST permit 7675:80 7675:100 no-export deny internet |
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When number is used for BGP community lists name, the number has special meanings. Community list number in the range from 1 and 99 is standard community-list. Community list number in the range from 100 to 199 is expanded community-list. These community lists are called as numbered community lists. On the other hand normal community lists is called as named community lists.
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In Route Map (see section 12. Route Map), we can match or set BGP communities attribute. Using this feature network operator can implement their network policy based on BGP communities attribute.
Following commands can be used in Route Map.
exact-match
keyword is spcified, match happen only when BGP
updates have completely same communities value specified in the
community list.
none
is specified as communities value, it removes entire
communities attribute from BGP updates. When community is not
none
, specified communities value is set to BGP updates. If
BGP updates already has BGP communities value, the existing BGP
communities value is replaced with specified community value.
When additive
keyword is specified, community is appended
to the existing communities value.
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To show BGP routes which has specific BGP communities attribute,
show ip bgp
command can be used. The community value and
community list can be used for show ip bgp
command.
internet
keyword can't be used for
community value. When exact-match
is specified, it
display only routes that have an exact match.
exact-match
is specified, display only routes
that have an exact match.
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Following configuration is the most typical usage of BGP communities attribute. AS 7675 provides upstream Internet connection to AS 100. When following configuration exists in AS 7675, AS 100 networks operator can set local preference in AS 7675 network by setting BGP communities attribute to the updates.
router bgp 7675 neighbor 192.168.0.1 remote-as 100 neighbor 192.168.0.1 route-map RMAP in ! ip community-list 70 permit 7675:70 ip community-list 70 deny ip community-list 80 permit 7675:80 ip community-list 80 deny ip community-list 90 permit 7675:90 ip community-list 90 deny ! route-map RMAP permit 10 match community 70 set local-preference 70 ! route-map RMAP permit 20 match community 80 set local-preference 80 ! route-map RMAP permit 30 match community 90 set local-preference 90 |
Following configuration announce 10.0.0.0/8 from AS 100 to AS 7675. The route has communities value 7675:80 so when above configuration exists in AS 7675, announced route's local preference will be set to value 80.
router bgp 100 network 10.0.0.0/8 neighbor 192.168.0.2 remote-as 7675 neighbor 192.168.0.2 route-map RMAP out ! ip prefix-list PLIST permit 10.0.0.0/8 ! route-map RMAP permit 10 match ip address prefix-list PLIST set community 7675:80 |
Following configuration is an example of BGP route filtering using communities attribute. This configuration only permit BGP routes which has BGP communities value 0:80 or 0:90. Network operator can put special internal communities value at BGP border router, then limit the BGP routes announcement into the internal network.
router bgp 7675 neighbor 192.168.0.1 remote-as 100 neighbor 192.168.0.1 route-map RMAP in ! ip community-list 1 permit 0:80 0:90 ! route-map RMAP permit in match community 1 |
Following exmaple filter BGP routes which has communities value 1:1. When there is no match community-list returns deny. To avoid filtering all of routes, we need to define permit any at last.
router bgp 7675 neighbor 192.168.0.1 remote-as 100 neighbor 192.168.0.1 route-map RMAP in ! ip community-list standard FILTER deny 1:1 ip community-list standard FILTER permit ! route-map RMAP permit 10 match community FILTER |
Communities value keyword internet
has special meanings in
standard community lists. In below example internet
act as
match any. It matches all of BGP routes even if the route does not
have communities attribute at all. So community list INTERNET
is same as above example's FILTER
.
ip community-list standard INTERNET deny 1:1 ip community-list standard INTERNET permit internet |
Following configuration is an example of communities value deletion.
With this configuration communities value 100:1 and 100:2 is removed
from BGP updates. For communities value deletion, only permit
community-list is used. deny
community-list is ignored.
router bgp 7675 neighbor 192.168.0.1 remote-as 100 neighbor 192.168.0.1 route-map RMAP in ! ip community-list standard DEL permit 100:1 100:2 ! route-map RMAP permit 10 set comm-list DEL delete |
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MPLS VPN/BGP provides VPN functionality by using MPLS network and BGP protocol support. MPLS VPN/BGP expands capability of network infrastructure. At the same time, it requires a new framework for policy routing. BGP Extended Communities Attribute is introduced for that. With BGP Extended Communities Attribute we can use Route Target or Site of Origin for implementing policy routing.
BGP Extended Communities Attribute is similar to BGP Communities Attribute. It is an optional transitive attribute. BGP Extended Communities Attribute can carry multiple Extended Community value. Each Extended Community value is eight octet length.
BGP Extended Communities Attribute provides an extended range compared with BGP Communities Attribute. Adding to that there is a type field in each value to provides community space structure.
There are two format to define Extended Community value. One is AS based format the other is IP address based format.
AS:VAL
AS
part is 2 octets Global Administrator subfield in Extended
Community value. VAL
part is 4 octets Local Administrator
subfield. 7675:100
represents AS 7675 policy value 100.
IP-Address:VAL
IP-Address
part is 4 octets Global Administrator subfield.
VAL
part is 2 octets Local Administrator subfield.
10.0.0.1:100
represents
9.9.1 BGP Extended Community Lists 9.9.2 BGP Extended Communities in Route Map
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Expanded Community Lists is a user defined BGP Expanded Community Lists.
# show ip extcommunity-list |
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9.10.1 Show IP BGP 9.10.2 More Show IP BGP
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BGP table version is 0, local router ID is 10.1.1.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path *> 1.1.1.1/32 0.0.0.0 0 32768 i Total number of prefixes 1 |
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When adding IPv6 routing information exchange feature to BGP. There were some proposals. IETF IDR working group finally take a proposal called Multiprotocol Extension for BGP. The specification is described in RFC2283. The protocol does not define new protocols. It defines new attributes to existing BGP. When it is used exchanging IPv6 routing information it is called BGP-4+. When it is used for exchanging multicast routing information it is called MBGP.
bgpd
supports Multiprotocol Extension for BGP. So if remote peer
supports the protocol, bgpd
can exchange IPv6 and/or multicast routing
information.
Traditional BGP does not have the feature to detect remote peer's
capability whether it can handle other than IPv4 unicast routes. This
is a big problem using Multiprotocol Extension for BGP to operational
network. draft-ietf-idr-bgp4-cap-neg-04.txt is proposing a
feature called Capability Negotiation. bgpd
use this Capability
Negotiation to detect remote peer's capabilities. If the peer is only
configured as IPv4 unicast neighbor, bgpd
does not send these Capability
Negotiation packets.
By default, Zebra will bring up peering with minimal common capability for the both sides. For example, local router has unicast and multicast capabilitie and remote router has unicast capability. In this case, the local router will establish the connection with unicast only capability. When there are no common capabilities, Zebra sends Unsupported Capability error and then resets the connection.
If you want to completely match capabilities with remote peer. Please
use strict-capability-match
command.
You may want to disable sending Capability Negotiation OPEN message
optional parameter to the peer when remote peer does not implement
Capability Negotiation. Please use dont-capability-negotiate
command to disable the feature.
When remote peer does not have capability negotiation feature, remote peer will not send any capabilities at all. In that case, bgp configures the peer with configured capabilities.
You may prefer locally configured capabilities more than the negotiated
capabilities even though remote peer sends capabilities. If the peer is
configured by override-capability
, bgpd
ignores received
capabilities then override negotiated capabilities with configured values.
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At an Internet Exchange point, many ISPs are connected to each other by
external BGP peering. Normally these external BGP connection are done by
full mesh
method. As with internal BGP full mesh formation,
this method has a scaling problem.
This scaling problem is well known. Route Server is a method to resolve the problem. Each ISP's BGP router only peers to Route Server. Route Server serves as BGP information exchange to other BGP routers. By applying this method, numbers of BGP connections is reduced from O(n*(n-1)/2) to O(n).
Unlike normal BGP router, Route Server must have several routing tables
for managing different routing policies for each BGP speaker. We call the
routing tables as different view
s. bgpd
can work as
normal BGP router or Route Server or both at the same time.
9.13.1 Multiple instance 9.13.2 BGP instance and view 9.13.3 Routing policy 9.13.4 Viewing the view
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To enable multiple view function of bgpd
, you must turn on
multiple instance feature beforehand.
When you want to make configuration more Cisco like one,
When bgp config-type cisco is specified,
"no synchronization" is displayed. "no auto-summary" is desplayed.
"network" and "aggregate-address" argument is displayed as "A.B.C.D M.M.M.M"
Zebra: network 10.0.0.0/8 Cisco: network 10.0.0.0
Zebra: aggregate-address 192.168.0.0/24 Cisco: aggregate-address 192.168.0.0 255.255.255.0
Community attribute handling is also different. If there is no configuration is specified community attribute and extended community attribute are sent to neighbor. When user manually disable the feature community attribute is not sent to the neighbor. In case of "bgp config-type cisco" is specified, community attribute is not sent to the neighbor by default. To send community attribute user has to specify "neighbor A.B.C.D send-community" command.
! router bgp 1 neighbor 10.0.0.1 remote-as 1 no neighbor 10.0.0.1 send-community !
! router bgp 1 neighbor 10.0.0.1 remote-as 1 neighbor 10.0.0.1 send-community !
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BGP instance is a normal BGP process. The result of route selection goes to the kernel routing table. You can setup different AS at the same time when BGP multiple instance feature is enabled.
bgp multiple-instance ! router bgp 1 neighbor 10.0.0.1 remote-as 2 neighbor 10.0.0.2 remote-as 3 ! router bgp 2 neighbor 10.0.0.3 remote-as 4 neighbor 10.0.0.4 remote-as 5 |
BGP view is almost same as normal BGP process. The result of route selection does not go to the kernel routing table. BGP view is only for exchanging BGP routing information.
With this command, you can setup Route Server like below.
bgp multiple-instance ! router bgp 1 view 1 neighbor 10.0.0.1 remote-as 2 neighbor 10.0.0.2 remote-as 3 ! router bgp 2 view 2 neighbor 10.0.0.3 remote-as 4 neighbor 10.0.0.4 remote-as 5 |
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You can set different routing policy for a peer. For example, you can set different filter for a peer.
bgp multiple-instance ! router bgp 1 view 1 neighbor 10.0.0.1 remote-as 2 neighbor 10.0.0.1 distribute-list 1 in ! router bgp 1 view 2 neighbor 10.0.0.1 remote-as 2 neighbor 10.0.0.1 distribute-list 2 in |
This means BGP update from a peer 10.0.0.1 goes to both BGP view 1 and view 2. When the update is inserted into view 1, distribute-list 1 is applied. On the other hand, when the update is inserted into view 2, distribute-list 2 is applied.
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To display routing table of BGP view, you must specify view name.
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zebra configuration =================== ! ! Actually there is no need to configure zebra ! bgpd configuration ================== ! ! This means that routes go through zebra and into the kernel. ! router zebra ! ! MP-BGP configuration ! router bgp 7675 bgp router-id 10.0.0.1 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 remote-as as-number ! address-family ipv6 network 3ffe:506::/32 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 activate neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 route-map set-nexthop out neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 remote-as as-number neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 route-map set-nexthop out exit-address-family ! ipv6 access-list all permit any ! ! Set output nexthop address. ! route-map set-nexthop permit 10 match ipv6 address all set ipv6 nexthop global 3ffe:1cfa:0:2:2c0:4fff:fe68:a225 set ipv6 nexthop local fe80::2c0:4fff:fe68:a225 ! ! logfile FILENAME is obsolete. Please use log file FILENAME ! log file bgpd.log ! |
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vtysh
is integrated shell of Zebra software.
To use vtysh please specify --enable-vtysh to configure script. To use PAM for authentication use --with-libpam option to configure script.
vtysh only searches /usr/local/etc path for vtysh.conf which is the vtysh configuration file. Vtysh does not search current directory for configuration file because the file includes user authentication settings.
Currently, vtysh.conf has only one command.
! username foo nopassword ! |
With this set, user foo does not need password authentication for user vtysh. With PAM vtysh uses PAM authentication mechanism.
If vtysh is compiled without PAM authentication, every user can use vtysh without authentication.
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Zebra provides many very flexible filtering features. Filtering is used for both input and output of the routing information. Once filtering is defined, it can be applied in any direction.
11.0.1 IP Access List 11.0.2 IP Prefix List
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Basic filtering is done by access-list
as shown in the
following example.
access-list filter deny 10.0.0.0/9 access-list filter permit 10.0.0.0/8 |
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ip prefix-list
provides the most powerful prefix based
filtering mechanism. In addition to access-list
functionality,
ip prefix-list
has prefix length range specification and
sequential number specification. You can add or delete prefix based
filters to arbitrary points of prefix-list using sequential number specification.
If no ip prefix-list is specified, it acts as permit. If ip prefix-list
is defined, and no match is found, default deny is applied.
You can create ip prefix-list
using above commands.
le
command specifies prefix length. The prefix list will be
applied if the prefix length is less than or equal to the le prefix length.
ge
command specifies prefix length. The prefix list will be
applied if the prefix length is greater than or equal to the ge prefix length.
Less than or equal to prefix numbers and greater than or equal to prefix numbers can be used together. The order of the le and ge commands does not matter.
If a prefix list with a different sequential number but with the exact same rules as a previous list is created, an error will result. However, in the case that the sequential number and the rules are exactly similar, no error will result.
If a list with the same sequential number as a previous list is created, the new list will overwrite the old list.
Matching of IP Prefix is performed from the smaller sequential number to the larger. The matching will stop once any rule has been applied.
In the case of no le or ge command,
Version 0.85: the matching rule will apply to all prefix lengths that matched the prefix list.
Version 0.86 or later: In the case of no le or ge command, the prefix length must match exactly the length specified in the prefix list.
11.0.2.1 ip prefix-list description 11.0.2.2 ip prefix-list sequential number control 11.0.2.3 Showing ip prefix-list 11.0.2.4 Clear counter of ip prefix-list
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Route map is a very useful function in zebra. There is a match and set statement permitted in a route map.
route-map test permit 10 match ip address 10 set local-preference 200 |
This means that if a route matches ip access-list number 10 it's local-preference value is set to 200.
12.0.1 Route Map Command 12.0.2 Route Map Match Command 12.0.3 Route Map Set Command
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Zebra fully supports IPv6 routing. As described so far, Zebra supports
RIPng, OSPFv3 and BGP-4+. You can give IPv6 addresses to an interface
and configure static IPv6 routing information. Zebra-IPv6 also provides
automatic address configuration via a feature called address
auto configuration
. To do it, the router must send router advertisement
messages to the all nodes that exist on the network.
13.1 Router Advertisement
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interface eth0 ipv6 nd send-ra ipv6 nd prefix-advertisement 3ffe:506:5009::/64 |
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There are several different methods for reading kernel routing table information, updating kernel routing tables, and for looking up interfaces.
netlink
. It makes asynchronous
communication between kernel and Zebra possible, similar to a routing
socket on BSD systems.
Before you use this feature, be sure to select (in kernel configuration) the kernel/netlink support option 'Kernel/User network link driver' and 'Routing messages'.
Today, the /dev/route special device file is obsolete. Netlink communication is done by reading/writing over netlink socket.
After the kernel configuration, please reconfigure and rebuild Zebra. You can use netlink as a dynamic routing update channel between Zebra and the kernel.
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SNMP (Simple Network Managing Protocol) is widely implemented feature for collecting network information from router and/or host. Zebra itself does not support SNMP agent functionality. But conjuction with SNMP agent, Zebra provides routing protocol MIBs.
Zebra uses SMUX protocol (RFC1227) for making communication with SNMP
agent. There are several SNMP agent which support SMUX. We recommend
to use the latest ucd-snmp
software.
15.1 How to get ucd-snmp 15.2 SMUX configuration
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ucd-snmp is a free software which distributed so called "as is" software
license. Please check the license which comes with distribution of
ucd-snmp
. The authors of ucd-snmp are the University of
California, the University of California at Davis, and the Electrical
Engineering department at the University of California at Davis.
You can get ucd-snmp from ftp://ucd-snmp.ucdavis.edu/. As of this
writing we are testing with ucd-snmp-4.1.pre1.tar.gz
.
To enable SMUX protocol support, please configure ucd-snmp
like below.
% configure --with-mib-modules=smux |
After compile and install ucd-snmp
, you will need to configure
smuxpeer. I'm now using configuration shown below. This means SMUX client
connects to MIB 1.3.6.1.6.3.1 with password test.
/usr/local/share/snmp/snmpd.conf ================================ smuxpeer 1.3.6.1.6.3.1 test |
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To enable SNMP support of Zebra, you have to configure Zebra with
--enable-snmp
(see section 2.1 Configure the Software).
! smux peer .1.3.6.1.6.3.1 test ! |
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Zebra Protocol is a protocol which is used between protocol daemon and zebra. Each protocol daemon sends selected routes to zebra daemon. Then zebra manages which route is installed into the forwarding table.
Zebra Protocol is a TCP-based protocol. Below is common header of Zebra Protocol.
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length (2) | Command (1) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
Length is total packet length including this header length. So minimum length is three. Command is Zebra Protocol command.
ZEBRA_INTERFACE_ADD 1 ZEBRA_INTERFACE_DELETE 2 ZEBRA_INTERFACE_ADDRESS_ADD 3 ZEBRA_INTERFACE_ADDRESS_DELETE 4 ZEBRA_INTERFACE_UP 5 ZEBRA_INTERFACE_DOWN 6 ZEBRA_IPV4_ROUTE_ADD 7 ZEBRA_IPV4_ROUTE_DELETE 8 ZEBRA_IPV6_ROUTE_ADD 9 ZEBRA_IPV6_ROUTE_DELETE 10 ZEBRA_REDISTRIBUTE_ADD 11 ZEBRA_REDISTRIBUTE_DELETE 12 ZEBRA_REDISTRIBUTE_DEFAULT_ADD 13 ZEBRA_REDISTRIBUTE_DEFAULT_DELETE 14 ZEBRA_IPV4_NEXTHOP_LOOKUP 15 ZEBRA_IPV6_NEXTHOP_LOOKUP 16 |
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
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Zebra can dump routing protocol packet into file with a binary format (see section 9.15 Dump BGP packets and table).
It seems to be better that we share the MRT's header format for backward compatibility with MRT's dump logs. We should also define the binary format excluding the header, because we must support both IP v4 and v6 addresses as socket addresses and / or routing entries.
In the last meeting, we discussed to have a version field in the header. But Masaki told us that we can define new `type' value rather than having a `version' field, and it seems to be better because we don't need to change header format.
Here is the common header format. This is same as that of MRT.
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Subtype | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
If `type' is PROTOCOL_BGP4MP, `subtype' is BGP4MP_STATE_CHANGE, and Address Family == IP (version 4)
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source AS number | Destination AS number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Index | Address Family | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Old State | New State | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
Where State is the value defined in RFC1771.
If `type' is PROTOCOL_BGP4MP, `subtype' is BGP4MP_STATE_CHANGE, and Address Family == IP version 6
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source AS number | Destination AS number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Index | Address Family | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Old State | New State | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
If `type' is PROTOCOL_BGP4MP, `subtype' is BGP4MP_MESSAGE, and Address Family == IP (version 4)
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source AS number | Destination AS number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Index | Address Family | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BGP Message Packet | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
Where BGP Message Packet is the whole contents of the BGP4 message including header portion.
If `type' is PROTOCOL_BGP4MP, `subtype' is BGP4MP_MESSAGE, and Address Family == IP version 6
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source AS number | Destination AS number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface Index | Address Family | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination IP address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BGP Message Packet | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
If `type' is PROTOCOL_BGP4MP, `subtype' is BGP4MP_ENTRY, and Address Family == IP (version 4)
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | View # | Status | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time Last Change | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Family | SAFI | Next-Hop-Len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Hop Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Length | Address Prefix [variable] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attribute Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BGP Attribute [variable length] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
If `type' is PROTOCOL_BGP4MP, `subtype' is BGP4MP_ENTRY, and Address Family == IP version 6
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | View # | Status | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time Last Change | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Family | SAFI | Next-Hop-Len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Hop Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Hop Address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Hop Address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Hop Address (Cont'd) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Length | Address Prefix [variable] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Prefix (cont'd) [variable] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attribute Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BGP Attribute [variable length] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
BGP4 Attribute must not contain MP_UNREACH_NLRI. If BGP Attribute has MP_REACH_NLRI field, it must has zero length NLRI, e.g., MP_REACH_NLRI has only Address Family, SAFI and next-hop values.
If `type' is PROTOCOL_BGP4MP and `subtype' is BGP4MP_SNAPSHOT,
0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | View # | File Name [variable] | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
The file specified in "File Name" contains all routing entries, which are in the format of "subtype == BGP4MP_ENTRY".
Constants: /* type value */ #define MSG_PROTOCOL_BGP4MP 16 /* subtype value */ #define BGP4MP_STATE_CHANGE 0 #define BGP4MP_MESSAGE 1 #define BGP4MP_ENTRY 2 #define BGP4MP_SNAPSHOT 3 |
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GNU/Linux has very flexible kernel configuration features. If you use GNU/Linux, make sure that the current kernel configuration is what you want. Zebra will run with any kernel configuration but some recommendations do exist.
zebra
can detect routing information
updates directly from the kernel (see section 14. Kernel Interface).
ripd
or
ospfd
because these protocols use multicast.
IPv6 support has been added in GNU/Linux kernel version 2.2. If you try to use the Zebra IPv6 feature on a GNU/Linux kernel, please make sure the following libraries have been installed. Please note that these libraries will not be needed when you uses GNU C library 2.1 or upper.
inet6-apps
inet6-apps
package includes basic IPv6 related libraries such
as inet_ntop
and inet_pton
. Some basic IPv6 programs such
as ping
, ftp
, and inetd
are also
included. The inet-apps
can be found at
ftp://ftp.inner.net/pub/ipv6/.
net-tools
net-tools
package provides an IPv6 enabled interface and
routing utility. It contains ifconfig
, route
,
netstat
, and other tools. net-tools
may be found at
http://www.tazenda.demon.co.uk/phil/net-tools/.
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1. Overview
2. Installation
3. Basic commands
4. Zebra
5. RIP
6. RIPng
7. OSPFv2
8. OSPFv3
9. BGP
10. VTY shell
11. Filtering
12. Route Map
13. IPv6 Support
14. Kernel Interface
15. SNMP Support
A. Zebra Protocol
B. Packet Binary Dump Format
Command Index
VTY Key Index
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