Skip to content

Announce your own prefixes

Purpose

As a network participating in the global Internet you want to tell other networks about your own prefixes and announce them to the public Internet.

Note

Your peers and upstreams might also apply incoming BGP filters to your BGP sessions and filter your prefixes. Please make sure to create appropriate RPKI objects, route/route6 objects and AS sets, for example in the RIPE datebase. It is best practice to also create an AS set although you currently only have one ASN, because if your BGP peers build filters based on your AS set you don't need to inform them if you ever announce prefixes with an additional origin ASN.

Configuration

Config snippet for JunOS

Please note that Cisco IOS is permissive by default. If you do not apply any filters, all prefixes will be shared between your BGP peers.

Config snippet for Cisco IOS

Config snippet for Cisco IOS XR

Config snippet for Arista EOS

Config snippet for FRRouting 

ip prefix-list outgoing seq 10 permit 192.0.2.0/24
ip prefix-list outgoing seq 100 deny 0.0.0.0/0 le 32

ipv6 prefix-list outgoing-6 seq 10 permit 2001:db8::/32
ipv6 prefix-list outgoing-6 seq 100 deny ::/0 le 128

router bgp 64496
  no bgp default ipv4-unicast
  bgp log-neighbor-changes
  bgp router-id 192.0.2.10

  neighbor 198.51.100.1 remote-as 65550
  neighbor 3fff::1582 remote-as 65550

  address-family ipv4 unicast
    network 192.0.2.0/24
    neighbor 198.51.100.1 activate
    neighbor 198.51.100.1 prefix-list outgoing out
  exit-address-family

  address-family ipv6 unicast
    network 2001:db8::/32
    neighbor 3fff::1582 activate
    neighbor 3fff::1582 prefix-list outgoing-6 out
  exit-address-family
exit

VyOS has two modes (operational and configuration mode). Enter configuration mode with configure to make changes. Use commit to apply them and save to keep them after reboot.

set policy prefix-list outgoing rule 10 action permit
set policy prefix-list outgoing rule 10 prefix 192.0.2.0/24
set policy prefix-list outgoing rule 100 action deny
set policy prefix-list outgoing rule 100 le 32
set policy prefix-list outgoing rule 100 prefix 0.0.0.0/0

set policy prefix-list6 outgoing-6 rule 10 action permit
set policy prefix-list6 outgoing-6 rule 10 prefix 2001:db8::/32
set policy prefix-list6 outgoing-6 rule 100 action deny
set policy prefix-list6 outgoing-6 rule 100 le 128
set policy prefix-list6 outgoing-6 rule 100 prefix ::/0

set protocols bgp system-as 64496

set protocols bgp parameters router-id 192.0.2.10

set protocols bgp parameters log-neighbor-changes
set protocols bgp parameters ebgp-requires-policy
set protocols bgp parameters network-import-check

set protocols bgp address-family ipv4-unicast network 192.0.2.0/24
set protocols bgp address-family ipv6-unicast network 2001:db8::/32

edit protocols bgp neighbor 198.51.100.1
set remote-as 65550
set address-family ipv4-unicast prefix-list export outgoing
exit

edit protocols bgp neighbor 3fff::1582
set remote-as 65550
set address-family ipv6-unicast prefix-list export outgoing-6
exit

Note

For dynamic routing, VyOS uses FRR. However, VyOS applies some potentially problematic defaults, such as:

To view the final FRR configuration, run: 

vtysh -c 'show running-config'
This should match the configuration in the FRR tab on this website.

Please refer to the VyOS 1.4 configuration guide first.

VyOS 1.5 introduces another potentially problematic default.

Starting with version 1.5, FRR is configured not to enforce the remote AS as the first AS in the AS_PATH. This setting is typically only necessary when connected to an IXP RS1.

To resolve this, you need to enable enforce-first-as for every neighbor.

For the configuration shown in the VyOS 1.4 tab, apply the following commands: 

set protocols bgp neighbor 198.51.100.1 enforce-first-as
set protocols bgp neighbor 3fff::1582 enforce-first-as

  1. Internet eXchange Points Route Servers ↩