Exchange routes through BGP

Ella Core uses kernel routes to forward user-plane traffic. These routes can be configured using BGP with tools such as FRR or BIRD.

This guide describes the steps required to install and configure FRR to exchange routes through BGP with other routers on your network.

Install FRR on the Ella Core host

Install FRR with this command:

sudo apt install frr

Enable the bgpd daemon

Edit the file /etc/frr/daemons. Change the line for bgpd to enable it:

bgpd=yes

Configure BGPd

In this guide, we assume a simple deployment with Ella Core on one host, and a single peer router. The following information represents the example deployment:

	Ella Core	Router
IP	192.168.5.10	192.168.5.1
AS Number	64513	64512

In Ella Core, we will assume that all the configured data networks will use subnets of 10.45.0.0/16, with minimums of /24. The currently configured data networks will be:

• 10.45.0.0/24
• 10.45.1.0/24

Edit the file /etc/frr/frr.conf to the following content:

frr version 8.4.4
frr defaults traditional
hostname ellacore
log syslog informational
no ip forwarding
no ipv6 forwarding
service integrated-vtysh-config
!
router bgp 64513
 bgp router-id 192.168.5.10
 no bgp network import-check
 neighbor 192.168.5.1 remote-as 64512
 !
 address-family ipv4 unicast
  network 10.45.0.0/24
  network 10.45.1.0/24
  neighbor 192.168.5.1 next-hop-self
  neighbor 192.168.5.1 prefix-list UNIVERSE in
  neighbor 192.168.5.1 prefix-list ELLA out
 exit-address-family
exit
!
ip prefix-list UNIVERSE seq 5 permit any
ip prefix-list ELLA seq 5 permit 10.45.0.0/16 le 24
!

Restart FRR:

sudo systemctl restart frr

Configure the BGP peer

The router should be configured to peer with Ella Core at this point. Follow your router's documentation for this step.

Validate the configuration

You can use the command vtysh to query the state of BGP:

sudo vtysh

ellacore# show bgp summary
IPv4 Unicast Summary (VRF default):
BGP router identifier 192.168.5.10, local AS number 64513 vrf-id 0
BGP table version 3
RIB entries 4, using 768 bytes of memory
Peers 1, using 724 KiB of memory

Neighbor          V         AS   MsgRcvd   MsgSent   TblVer  InQ OutQ  Up/Down State/PfxRcd   PfxSnt Desc
192.168.5.1       4      64512       109       110        0    0    0 01:45:13            1        2 N/A

Total number of neighbors 1

ellacore# show bgp ipv4
BGP table version is 3, local router ID is 192.168.5.10, vrf id 0
Default local pref 100, local AS 64513
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          Next Hop            Metric LocPrf Weight Path
*> 0.0.0.0/0        192.168.5.1               0             0 64512 i
*> 10.46.0.0/24     0.0.0.0                  0         32768 i
*> 10.46.1.0/24     0.0.0.0                  0         32768 i

Displayed  3 routes and 3 total paths

Adding a new data network to BGP

Adding a new data network in Ella Core will not automatically add it to BGP at this time. These steps describe how to add the new subnet:

sudo vtysh

configure
router bgp 64513
network 10.46.2.0/24
exit
exit
write
exit