Frr

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This article has some todo items:
  • add systemd configuration steps

FRR is a set of unified tools to configure and manage dynamic routing protocols. It was created as a fork from the Quagga Project.

The FRRouting software consists of 2 basic parts:

  • The zebra daemon
  • The routing process deamons: ripd,ospfd etc.

The zebra daemon is a abstraction layer between the kernel and the running routing processes. zebra acts as a relay. Each routing protocol such as as BFD, BGP, Babel, OpenFabric, LDP, EIGRP, ISIS, NHRP, OSPFv2, OSPFv3, Segment Routing, PIM, PBR, RIP, RIPng, STATIC and VRRP runs its own separate running daemon.

FRRouting can install, add, change and remove kernel IP routing information. All routing daemons communicate directly to zebra daemon. The zebra daemon then, alters the linux IP networking information on the host. iproute2 and nettools alter directly the linux IP networking.

Control Plane bgpd ospfd ospf6d ripngd isisd pimd ldpd babeld bfdd fabricd pathd (...) iproute2 BIRD ethtool other tool
zebra
Data Plane Linux kernel IP networking
Hardware eth0 enp8s0 wlan1 other interface

Installation

SLOTTING

It's important to know that frr does not typically maintain full backwards compatibility between versions. For reference:

As can be seen blind upgrades are dangerous for frr with potentially catastrophic consequences. For this reason we've decided to (starting with frr 9.0.4, 9.1.2, 10.0.2 and 10.1.1) SLOT frr into sub-slots based on major.minor version. This allows you to emerge net-misc/frr:0/9.1 for example. This will add net-misc/frr to world, and may still result in upgrades happening when upgrading world unless you take precautionary measures. To prevent this you have three options (none of which the author is lead to understood is generally supported).

Option 1: edit /var/lib/portage/world manually, eg: 

$ grep frr world
net-misc/frr:0/9.1

Option 2: mask net-misc/frr and unmask net-misc/frr:0/9.1, eg: 

/etc/portage # grep frr -r package.*
package.mask/99frr:net-misc/frr
package.unmask/99frr:net-misc/frr:0/9.1

This has the downside that if (when) we mask a subslot you may not notice. Eg, if we now proceed to add net-misc/frr:0/9.1 to packages.mask globally, then your unmask will override that.

Option 3: mask newer versions only, eg: 

/etc/portage # grep frr -r package.*
package.mask/99frr:>=net-misc/frr-10.0*

Please note that wherever possible we will endeavour to hard-mask a slot at least 30 days prior to removal, most likely by way of KEYWORDS=-* to accommodate all options above, in addition to adding an entry to packages.mask to clarify why.

USE flags

USE flags for net-misc/frr The FRRouting Protocol Suite

doc Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
fpm Enable Forwarding Plane Manager support
grpc Enable gRPC plugin
nhrp Build Next Hop Resolution Protocol daemon
ospfapi Build OSPFAPI support
pam Add support for PAM (via sys-libs/pam) to the Virtual Terminal Interface Shell (vtysh)
rpki Enable RPKI
snmp Add support for the Simple Network Management Protocol if available
test Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)
Data provided by the Gentoo Package Database · Last update: 2025-03-25 04:35 More information about USE flags

Emerge

root #emerge --ask net-misc/frr

Configuration

Review frr's configuration /etc/frr/daemons file to enable additional routing protocols. In the default setting all routing protocols are disabled.

  • /etc/frr/daemons - Global (system wide) FRR configuration file.
FILE /etc/frr/daemons
...
bgpd=no
ospfd=no
ospf6d=no
ripd=no
ripngd=no
isisd=no
pimd=no
ldpd=no
nhrpd=no
eigrpd=no
babeld=no
sharpd=no
pbrd=no
bfdd=no
fabricd=no
vrrpd=no
pathd=no
...

Add larry to frrvty group to be able to use vtysh:

root #gpasswd -a larry frrvty

Add larry to the frr group:

root #gpasswd -a larry frr

OpenRC

Add frr to the default runlevel:

root #rc-update add frr default

Start frr daemon:

root #/etc/init.d/frr start

systemd

Note
If the main routing table is large, you may want to remove the myhostname module from the host entry in /etc/nsswitch.conf to avoid slow DNS lookups [1]

Usage

Following section describes a basic configuration example for FRR. Configuring a additional IP address 192.0.2.100/32 and the IPv6 address 2001:db8::100/128 on a loopback interface lo, then finally to test in using iproute2 tools. The goal of this usage configuration example is to show, FRR is yet another management tool for the linux kernel IP networking.

Commands overview:

Action Command
Use vtysh to configure frr
user $vtysh
Show help using the ? key.
Router#?
Show basic IP networking information
Router#show ip route
Show running configuration
Router#show run
Get into global configuration mode
Router#conf
Change int interface configuration mode, interface loopback
Router(config)#int lo
Configure IP address on a loopback interface
Router(config-if)#ip address 192.0.2.100/32
Configure IPv6 address on a loopback interface
Router(config-if)#ipv6 address 2001:db8::100/128
Exit global configuration mode
Router(config-if)#end
Show current configuration
Router#show int lo
Save frr configuration
Router#wr
Display configured IP address using iproute2
user $ip add

Initial IP network settings used during the example configuration:

Initial networking setup
Interface Settings IP IPv6
lo address 127.0.0.1 ::1
netmask /32 /128
wlan0 address 192.0.2.10 2001:db8::10
netmask /24 /64
gateway 192.0.2.1 2001:db8::1

Display configured IP settings using iproute2:

user $ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 brd 127.255.255.255 scope host lo
       valid_lft forever preferred_lft forever
2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether de:ad:be:ef:de:ad brd ff:ff:ff:ff:ff:ff
    inet 192.0.2.10/24 brd 192.0.2.255 scope global wlan0

Display the IPv6 interface configuration using iproute2:

user $ip -6 add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN qlen 1000
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
    inet6 2001:db8::10/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::eac:d1ff:fe94:0/64 scope link
       valid_lft forever preferred_lft forever

Show the Linux IPv4 routing table:

user $ip route
default via 192.0.2.1 dev wlan0  metric 2005
192.0.2.0/24 dev wlan0 proto kernel scope link src 192.0.2.10

Show the Linux IPv6 routing table:

user $ip -6 route
default via 2001:db8::1 dev wlan0 metric 1024 pref medium
2001:db8::/64 dev wlan0 proto kernel metric 256 pref medium
fe80::/64 dev wlan0 proto kernel metric 256 pref medium

Login

Use the vtysh command to login to the FRR command line interface:

user $vtysh
Hello, this is FRRouting (version 8.1-gentoo).
Copyright 1996-2005 Kunihiro Ishiguro, et al.

Router#

Show routing table

Compare output shown below to the Linux ip route, shows exactly same output. Notice the default route has a K prefix which means it is a kernel route:

Router#show ip route 
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
       f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

K>* 0.0.0.0/0 [0/0] via 192.0.2.1, eth0, 00:00:09
C>* 192.0.2.0/24 is directly connected, eth0, 00:13:52

Now the same, but for the IPv6 protocol:

Router#show ipv6 route 
Codes: K - kernel route, C - connected, S - static, R - RIPng,
       O - OSPFv3, I - IS-IS, B - BGP, N - NHRP, T - Table,
       v - VNC, V - VNC-Direct, A - Babel, F - PBR,
       f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

K>* ::/0 [0/1024] via 2001:db8::1, wlan0, 00:04:44
C>* 2001:db8::/64 is directly connected, wlan0, 00:12:00
C>* fe80::/64 is directly connected, wlan0, 00:12:03

Show configuration

To display current configuration use the show running-config command:

Router#show run 
Building configuration...

Current configuration:
!
frr version 8.1-gentoo
frr defaults traditional
hostname Router
service integrated-vtysh-config
!
end

Configure IP addressing

Get into edit mode:

Router#conf 
Router(config)#

Choose the lo loopback interface:

Router(config)#int lo 
Router(config-if)#

Configure the IP 192.0.2.100/32 on loopback interface, notice the IP prefix length /32:

Router(config-if)#ip address 192.0.2.100/32

Configure the IPv6 address 2001:db8::100/128 on the loopback interface, notice the /128 prefix length:

Router(config-if)#ipv6 address 2001:db8::100/128

Exit configure mode

End the edit mode mode session:

Router(config-if)#end 
Router#

Verify configuration

Show running configuration:

Router#show run 
Current configuration:
!
frr version 8.1
frr defaults traditional
hostname Router
service integrated-vtysh-config
!
interface lo
 ip address 192.0.2.100/32
 ipv6 address 2001:db8::100/128
exit
!
end

Show the loopback interface configuration, and notice the configured inet and inet6 addresses in the output:

Router#sh int lo 
Interface lo is up, line protocol is up
  Link ups:       0    last: (never)
  Link downs:     0    last: (never)
  vrf: default
  index 1 metric 0 mtu 65536 speed 0
  flags: <UP,LOOPBACK,RUNNING>
  Type: Loopback
  inet 192.0.2.100/32
  inet6 2001:db8::100/128
  Interface Type Other
  Interface Slave Type None
  protodown: off

Show the IPv4 routing table, notify both prefixes 192.0.2.10/24 and 192.0.2.100/32 are in the routing table:

Router#show ip route 
Codes: K - kernel route, C - connected, S - static, R - RIP,
       O - OSPF, I - IS-IS, B - BGP, E - EIGRP, N - NHRP,
       T - Table, v - VNC, V - VNC-Direct, A - Babel, F - PBR,
       f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

C>* 192.0.2.10/24 is directly connected, wlan0, 00:05:14
C>* 192.0.2.100/24 is directly connected, lo, 00:05:14

Show the IPv6 routing table, notify both prefixes 2001:db8::/64 and 2001:db8::100/128 are in the routing table:

Router#show ipv6 route 
frr# show ipv6 route
Codes: K - kernel route, C - connected, S - static, R - RIPng,
       O - OSPFv3, I - IS-IS, B - BGP, N - NHRP, T - Table,
       v - VNC, V - VNC-Direct, A - Babel, F - PBR,
       f - OpenFabric,
       > - selected route, * - FIB route, q - queued, r - rejected, b - backup
       t - trapped, o - offload failure

C>* 2001:db8::/64 is directly connected, wlan0, 00:24:31
C>* 2001:db8::100/128 is directly connected, lo, 00:31:28
C>* fe80::/64 is directly connected, eth0, 00:56:16

Save configuration

Save running configuration:

Router#write 
Building Configuration...
Integrated configuration saved to /etc/frr/frr.conf
[OK]

Exit router

Exit FRR using the exit command:

Router#exit

Test connectivity

Verify IP configuration using iproute2. Notice the additional IP address setup on loopback interface:

user $ip add
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet 192.168.0.100/32 brd 192.168.0.100 scope global lo
       valid_lft forever preferred_lft forever
    inet6 2001:db8::100/128 scope global
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
1: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 0c:ac:d1:94:00:00 brd ff:ff:ff:ff:ff:ff
    inet 192.0.2.10/24 brd 192.0.2.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 2001:db8::10/64 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::eac:d1ff:fe94:0/64 scope link
       valid_lft forever preferred_lft forever

Verify IP connectivity in the network:

user $ping 192.0.2.100
PING 192.0.2.100 (192.0.2.100): 56 data bytes
64 bytes from 192.0.2.100: seq=0 ttl=42 time=0.051 ms
^C
--- 192.0.2.100 ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.051/0.051/0.051 ms

Verify IPv6 connectivity in the network:

user $ping 2001:db8::100
PING 2001:db8::100 (2001:db8::100): 56 data bytes
64 bytes from 2001:db8::100: seq=0 ttl=64 time=0.062 ms
^C
--- 2001:db8::100 ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 0.058/0.058/0.058 ms

Remove configuration

Remove the example configuration using the using vtysh:

user $vtysh

Apply following command sequence to remove the configuration: 

conf
interface lo
 no ip address 192.0.2.100/32
 no ipv6 address 2001:db8::100/128
end
wr

Troubleshooting

Verify the zebra daemon is up and running:

root #ss -tulpn | grep zebra
tcp   LISTEN 0      3          127.0.0.1:2601      0.0.0.0:*    users:(("zebra",pid=1799,fd=22))

Verify configured routing protocol daemons are up and running:

root #ss -tulpn | egrep 'Net|:26'
Netid State  Recv-Q Send-Q Local Address:Port Peer Address:PortProcess
tcp   LISTEN 0      3          127.0.0.1:2608      0.0.0.0:*    users:(("isisd",pid=1823,fd=11))
tcp   LISTEN 0      3          127.0.0.1:2609      0.0.0.0:*    users:(("babeld",pid=1826,fd=10))
tcp   LISTEN 0      3          127.0.0.1:2611      0.0.0.0:*    users:(("pimd",pid=1829,fd=12))
tcp   LISTEN 0      3          127.0.0.1:2612      0.0.0.0:*    users:(("ldpd",pid=1838,fd=17))
tcp   LISTEN 0      3          127.0.0.1:2616      0.0.0.0:*    users:(("staticd",pid=1842,fd=11))
tcp   LISTEN 0      3          127.0.0.1:2617      0.0.0.0:*    users:(("bfdd",pid=1845,fd=18))
tcp   LISTEN 0      3          127.0.0.1:2601      0.0.0.0:*    users:(("zebra",pid=1799,fd=22))
tcp   LISTEN 0      3          127.0.0.1:2602      0.0.0.0:*    users:(("ripd",pid=1811,fd=11))
tcp   LISTEN 0      3          127.0.0.1:2604      0.0.0.0:*    users:(("ospfd",pid=1817,fd=11))
tcp   LISTEN 0      3          127.0.0.1:2605      0.0.0.0:*    users:(("bgpd",pid=1804,fd=17))
tcp   LISTEN 0      3              [::1]:2606         [::]:*    users:(("ospf6d",pid=1820,fd=11))
tcp   LISTEN 0      3              [::1]:2603         [::]:*    users:(("ripngd",pid=1814,fd=11))

Using help

Show basic mode commands, use the ? key for help:

Router#?

After choosing initial entry command show, continue using ? key to display further possible commands:

Router#show ?

Continue using the ? help key on each command level, to view possible configuration settings.

Router#show ip ?

Show the routing table:

Router#show ip route

Internal help works like a tree, where using the ? key displays further levels of commands.

Routing protocol debugging

Depending on the used FRRouting version, there are 2 different ways to display the routing protocol debugging output. Method 2 is the more universal working method that will work using all FRRouting versions.

Method 1

Note
This works using FRR version 9.x. and higher.

Since FRRouting version 9 it is possible to get routing protocol debug messages displayed using vtysh only. Without leaving the vtysh default prompt.

Enable babel route debugging using the debug babel route command:

Router#debug babel route

To view the protocol debugging in the prompt use the terminal monitor command

Router#terminal monitor 
2023-10-15 09:08:09.231 [DEBG] babeld: [N3PWX-KJW20] Modify route: delete old; add new.
2023-10-15 09:08:09.231 [DEBG] babeld: [K58FD-K9K7G] removing route (ipv6) to zebra
2023-10-15 09:08:09.231 [DEBG] babeld: [K58FD-K9K7G] adding route (ipv6) to zebra

Disable debugging output after finishing troubleshooting:

Router#no terminal monitor
Router#no debug babel route

Method 2

Tip
This debugging aproach works using all FRR versions

To view protocol debug output, use the log syslog debugging configuration to write the debugging output systems to /var/log/messages file: 

conf
log syslog debugging
exit

Get and overview of the debugging options:

Router#debug ?

In example below a simple debug rip events routine is shown:

Router#debug rip events

View the routing protocol debug events in the system syslog /var/log/messages file:

root #tail -f /var/log/messages 
Apr  2 15:19:38 Router daemon.debug ripd[1811]: [RG149-CQVW5] update timer fire!
Apr  2 15:19:38 Router daemon.debug ripd[1811]: [V19ZJ-CH6H5] SEND UPDATE to eth0 ifindex 2
Apr  2 15:19:38 Router daemon.debug ripd[1811]: [RDKCB-7NMQT] multicast announce on eth0
Apr  2 15:19:38 Router daemon.debug ripd[1811]: [JEJ1H-ZE96E] update routes on interface eth0 ifindex 2
Apr  2 15:19:38 Router daemon.debug ripd[1811]: [VEJY5-67P5X] SEND to  224.0.0.9520
Apr  2 15:20:14 Router daemon.debug ripd[1811]: [RG149-CQVW5] update timer fire!
Apr  2 15:20:14 Router daemon.debug ripd[1811]: [V19ZJ-CH6H5] SEND UPDATE to eth0 ifindex 2
Apr  2 15:20:14 Router daemon.debug ripd[1811]: [RDKCB-7NMQT] multicast announce on eth0
Apr  2 15:20:14 Router daemon.debug ripd[1811]: [JEJ1H-ZE96E] update routes on interface eth0 ifindex 2
Apr  2 15:20:14 Router daemon.debug ripd[1811]: [VEJY5-67P5X] SEND to  224.0.0.9520

Disable debugging output after finishing troubleshooting:

Router#no debug rip events

See also

  • Iproute2 — a tool developed to unify network interface configuration, routing, and tunneling for Linux systems.
  • Static routing — covers routing of the IP protocol in the Linux kernel.
  • BIRD — routing daemon implementing OSPF, RIPv2 & BGP, Babel for IP

External resources

Retrieved from "https://wiki.gentoo.org/index.php?title=Frr&oldid=1314918"