BGP

BGP (Border Gateway Protocol) is one of the Exterior Gateway Protocols and the de facto standard interdomain routing protocol. The latest BGP version is 4. BGP-4 is described in :rfc:`1771 and updated by RFC 4271. RFC 2858 adds multiprotocol support to BGP.

IPv4

A simple eBGP configuration:

Node 1:

set protocols bgp 65534 neighbor 192.168.0.2 ebgp-multihop '2'
set protocols bgp 65534 neighbor 192.168.0.2 remote-as '65535'
set protocols bgp 65534 neighbor 192.168.0.2 update-source '192.168.0.1'
set protocols bgp 65534 address-family ipv4-unicast network '172.16.0.0/16'
set protocols bgp 65534 parameters router-id '192.168.0.1'

Node 2:

set protocols bgp 65535 neighbor 192.168.0.1 ebgp-multihop '2'
set protocols bgp 65535 neighbor 192.168.0.1 remote-as '65534'
set protocols bgp 65535 neighbor 192.168.0.1 update-source '192.168.0.2'
set protocols bgp 65535 address-family ipv4-unicast network '172.17.0.0/16'
set protocols bgp 65535 parameters router-id '192.168.0.2'

Don’t forget, the CIDR declared in the network statement MUST exist in your routing table (dynamic or static), the best way to make sure that is true is creating a static route:

Node 1:

set protocols static route 172.16.0.0/16 blackhole distance '254'

Node 2:

set protocols static route 172.17.0.0/16 blackhole distance '254'

IPv6

A simple BGP configuration via IPv6.

Node 1:

set protocols bgp 65534 neighbor 2001:db8::2 ebgp-multihop '2'
set protocols bgp 65534 neighbor 2001:db8::2 remote-as '65535'
set protocols bgp 65534 neighbor 2001:db8::2 update-source '2001:db8::1'
set protocols bgp 65534 neighbor 2001:db8::2 address-family ipv6-unicast
set protocols bgp 65534 address-family ipv6-unicast network '2001:db8:1::/48'
set protocols bgp 65534 parameters router-id '10.1.1.1'

Node 2:

set protocols bgp 65535 neighbor 2001:db8::1 ebgp-multihop '2'
set protocols bgp 65535 neighbor 2001:db8::1 remote-as '65534'
set protocols bgp 65535 neighbor 2001:db8::1 update-source '2001:db8::2'
set protocols bgp 65535 neighbor 2001:db8::1 address-family ipv6-unicast
set protocols bgp 65535 address-family ipv6-unicast network '2001:db8:2::/48'
set protocols bgp 65535 parameters router-id '10.1.1.2'

Don’t forget, the CIDR declared in the network statement MUST exist in your routing table (dynamic or static), the best way to make sure that is true is creating a static route:

Node 1:

set protocols static route6 2001:db8:1::/48 blackhole distance '254'

Node 2:

set protocols static route6 2001:db8:2::/48 blackhole distance '254'

Route Filter

Route filter can be applied using a route-map:

Node1:

set policy prefix-list AS65535-IN rule 10 action 'permit'
set policy prefix-list AS65535-IN rule 10 prefix '172.16.0.0/16'
set policy prefix-list AS65535-OUT rule 10 action 'deny'
set policy prefix-list AS65535-OUT rule 10 prefix '172.16.0.0/16'
set policy prefix-list6 AS65535-IN rule 10 action 'permit'
set policy prefix-list6 AS65535-IN rule 10 prefix '2001:db8:2::/48'
set policy prefix-list6 AS65535-OUT rule 10 action 'deny'
set policy prefix-list6 AS65535-OUT rule 10 prefix '2001:db8:2::/48'
set policy route-map AS65535-IN rule 10 action 'permit'
set policy route-map AS65535-IN rule 10 match ip address prefix-list 'AS65535-IN'
set policy route-map AS65535-IN rule 10 match ipv6 address prefix-list 'AS65535-IN'
set policy route-map AS65535-IN rule 20 action 'deny'
set policy route-map AS65535-OUT rule 10 action 'deny'
set policy route-map AS65535-OUT rule 10 match ip address prefix-list 'AS65535-OUT'
set policy route-map AS65535-OUT rule 10 match ipv6 address prefix-list 'AS65535-OUT'
set policy route-map AS65535-OUT rule 20 action 'permit'
set protocols bgp 65534 neighbor 2001:db8::2 route-map export 'AS65535-OUT'
set protocols bgp 65534 neighbor 2001:db8::2 route-map import 'AS65535-IN'

Node2:

set policy prefix-list AS65534-IN rule 10 action 'permit'
set policy prefix-list AS65534-IN rule 10 prefix '172.17.0.0/16'
set policy prefix-list AS65534-OUT rule 10 action 'deny'
set policy prefix-list AS65534-OUT rule 10 prefix '172.17.0.0/16'
set policy prefix-list6 AS65534-IN rule 10 action 'permit'
set policy prefix-list6 AS65534-IN rule 10 prefix '2001:db8:1::/48'
set policy prefix-list6 AS65534-OUT rule 10 action 'deny'
set policy prefix-list6 AS65534-OUT rule 10 prefix '2001:db8:1::/48'
set policy route-map AS65534-IN rule 10 action 'permit'
set policy route-map AS65534-IN rule 10 match ip address prefix-list 'AS65534-IN'
set policy route-map AS65534-IN rule 10 match ipv6 address prefix-list 'AS65534-IN'
set policy route-map AS65534-IN rule 20 action 'deny'
set policy route-map AS65534-OUT rule 10 action 'deny'
set policy route-map AS65534-OUT rule 10 match ip address prefix-list 'AS65534-OUT'
set policy route-map AS65534-OUT rule 10 match ipv6 address prefix-list 'AS65534-OUT'
set policy route-map AS65534-OUT rule 20 action 'permit'
set protocols bgp 65535 neighbor 2001:db8::1 route-map export 'AS65534-OUT'
set protocols bgp 65535 neighbor 2001:db8::1 route-map import 'AS65534-IN'

We could expand on this and also deny link local and multicast in the rule 20 action deny.

RPKI

RPKI is a framework PKI designed to secure the Internet routing insfratructure. It associate a BGP route announcement with the correct originating ASN and check it validation. RPKI described in RFC 6480. This is a separate server. You can find more details at RIPE-NNC.

Imported prefixes during the validation may have values: valid, invalid and notfound.

  • The valid state means that prefix and ASN that originated it match the ROA base.
  • Invalid means that prefix/prefix length and ASN that originated it doesn’t match with ROA.
  • Notfound means that prefix not found in ROA.

We can build route-maps for import, based on these states. Simple RPKI configuration, where ‘routinator’ - RPKI cache server with ip ‘10.11.11.1’.

set protocols rpki cache routinator address '10.11.11.1'
set protocols rpki cache routinator port '3323'

Example route-map for import. We can set local-preference logic based on states. Also we may not import prefixes with the state ‘invalid’.

set policy route-map ROUTES-IN rule 10 action 'permit'
set policy route-map ROUTES-IN rule 10 match rpki 'valid'
set policy route-map ROUTES-IN rule 10 set local-preference '300'
set policy route-map ROUTES-IN rule 20 action 'permit'
set policy route-map ROUTES-IN rule 20 match rpki 'notfound'
set policy route-map ROUTES-IN rule 20 set local-preference '125'
set policy route-map ROUTES-IN rule 30 action 'deny'
set policy route-map ROUTES-IN rule 30 match rpki 'invalid'