[c-nsp] BGP/private and public ASN mix trick

Nick Kraal nick at arc.net.my
Sat Aug 25 10:38:05 EDT 2007


Dear all,

I have a tricky/creative arrangement here to provide to a customer.

[1] The customer has their own prefixes [a.b.c.d/20], but no ASN.
[2] We plan to run private BGP with the customer to receive this
     prefix, and for us to announce the global routing table.
[3] Objective is to then announce this prefix as originating from AS111
     to all AS111 public BGP peers.
[4] Sample configuration at the end of this e-mail. Any potential traps
     here?
[5] Prefix list [TUN-CUST-CIDR-BLOCK] is then used in route-maps with
     other BGP peers. Are removing private-as and the inbound route-map
     sufficient for BGP to pick this prefix up and announce it as AS111?

Thanks in advance,

-nick/
======================
Current configuration:

router bgp 111
  neighbor 200.100.1.10 remote-as 64001
!
address-family ipv4
neighbor 203.100.1.10 activate
neighbor 203.100.1.10 next-hop-self
neighbor 203.100.1.10 remove-private-as
neighbor 200.100.1.10 soft-reconfiguration inbound
neighbor 200.100.1.10 route-map TUN-CUST-FILTER-IN in
neighbor 200.100.1.10 route-map TUN-CUST-FILTER-OUT out
!
route-map TUN-CUST-FILTER-IN permit 5
  match ip address TUN-CUST-CIDR-BLOCK
  set origin igp
!
route-map TUN-CUST-FILTER-OUT permit 10
  match as-path 75
!
ip prefix-list TUN-CUST-CIDR-BLOCK seq 5 permit a.b.c.d/20



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