2.3 orf questions about direction

Cisco documentation shows that the side of the connection with the route blocking, is configured for orf receive. The other side of the connection is configured for send. This is the way i configured the routers and it works. E.G.(r1 - send | r4 - receive)

The SG is configured for the opposite (R1 - receive | R4 - send).

 

I'm confused at which is the right way and why they both work.

 

 

 

router bgp 200

 no synchronization

 bgp router-id 150.1.4.4

 bgp log-neighbor-changes

 neighbor 130.1.45.5 remote-as 200

 neighbor 130.1.124.1 remote-as 100

 neighbor 130.1.124.1 capability orf prefix-list receive

 neighbor 130.1.124.1 prefix-list BGP-FROM-R1 in

 neighbor 150.1.3.3 remote-as 200

 no auto-summary

Rack1R4#sh ip bgp       

BGP table version is 3, local router ID is 150.1.4.4

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

              r RIB-failure, S Stale

Origin codes: i - IGP, e - EGP, ? - incomplete

 

   Network          Next Hop            Metric LocPrf Weight Path

*> 28.119.16.0/24   130.1.124.1                            0 100 54 i

*> 28.119.17.0/24   130.1.124.1                            0 100 54 i

 

Comments

  • Cisco documentation shows that the side of the connection with the route blocking, is configured for orf receive. The other side of the connection is configured for send. This is the way i configured the routers and it works. E.G.(r1 - send | r4 - receive)

    The SG is configured for the opposite (R1 - receive | R4 - send).

    I'm confused at which is the right way and why they both work.

    SG has the correct way to apply orf. Here is the sample from the Cisco DoC


    http://www.cisco.com/en/US/docs/ios/iproute_bgp/command/reference/irg_bgp3.html#wp1105692

    Router-A Configuration (Sender)

    The following example creates an outbound route filter and configures Router-A (10.1.1.1) to advertise the filter to Router-B (172.16.1.2). An IP prefix list named FILTER is created to specify the 192.168.1.0/24 subnet for outbound route filtering. The ORF send capability is configured on Router-A so that Router-A can advertise the outbound route filter to Router-B.


    ip prefix-list FILTER seq 10 permit 192.168.1.0/24 


    !


    router bgp 100


     address-family ipv4 unicast 


     neighbor 172.16.1.2 remote-as 200


     neighbor 172.16.1.2 ebgp-multihop 


     neighbor 172.16.1.2 capability orf prefix-list send


     neighbor 172.16.1.2 prefix-list FILTER in


     exit 

    Router-B Configuration (Receiver)

    The following example configures Router-B to advertise the ORF receive capability to Router-A. Router-B will install the outbound route filter, defined in the FILTER prefix list, after ORF capabilities have been exchanged. An inbound soft reset is initiated on Router-B at the end of this configuration to activate the outbound route filter.


    router bgp 200


     address-family ipv4 unicast 


     neighbor 10.1.1.1 remote-as 100


     neighbor 10.1.1.1 ebgp-multihop 255


     neighbor 10.1.1.1 capability orf prefix-list receive


     end 


    clear ip bgp 10.1.1.1 in prefix-filter

     

  • This is the cisco doc i was reading. It has it the opposite. The confusing part for me, is it works with the send and receive either way.

     

    http://www.cisco.com/en/US/docs/ios/12_2t/12_2t11/feature/guide/ft11borf.html#wp1036826

  • you apply a prefix list filter inbound on a neighbor to block certain prefixes, ORF sends / advertises that prefix list to that neighbor which recieves it and applies the prefix-list outbound, therefore no longer advertising the blocked prefixes.

Sign In or Register to comment.