[j-nsp] BGP Communities

Paul Stewart paul at paulstewart.org
Wed May 5 10:05:42 EDT 2010


Good morning.. I hope I'm not being a "pain" to folks on the list.. J

 

So we have our first MX480 up and running now - things are progressing along
nicely thanks to all the help from this list. OSPF, IPv4/IPv6, iBGP up and
running.

 

Having a small issue around eBGP peering.  When I bring up a session we are
receiving routes from a peer just fine and assigning a community to it.  The
community is visible across our other Cisco boxes as well confirming that
part if working.

 

Our BGP import/export to peers/transit/customers is driven by communities..

 

My problem is that we are not advertising any prefixes out to eBGP peers for
some reason and I'm trying to diagnose why..

 

When I do "show route community 11666:5000" I get a list of the proper
prefixes as expected.  11666:5000 is our own network routes.  The same
occurs when I list 11666:4000 which is customer network routes - displays
the list correctly.  This confirms in my mind that the MX480 is receiving
correct communities from neighboring iBGP boxes..

 

protocols {

    bgp {

        group peering-xyz {

            type external;

            description xxxxx;

            import inbound-xxxx;

            export outbound-xxx;

            neighbor xxx.xx.235.33 {

                description xxxxxxxx;

                family inet {

                    unicast {

                        prefix-limit {

                            maximum 10;

                        }

                    }

                }

                peer-as 12345;

            }

 

 

policy-options {

    policy-statement inbound-xxxxx {

        term ottix1 {

            then {

                metric 110;

                local-preference 200;

                community add inbound-xxxx;

                accept;

            }

        }

    }

 

    policy-statement outbound-xxxxxx {

        term ottix1 {

            from community outbound-xxxxxx;

            then {

                metric 110;

                accept;

            }

        }

        term ottix2 {

            then reject;

        }

    }

    community inbound-xxxx members [ 11666:2000 11666:2002 ];

    community outbound-xxxx members [ 11666:4000 11666:5000 ];

 

 

The inbound section is working as expected and getting assigned communities
11666:2000 and 11666:2002

 

The outbound section isn't sending anything from communities 11666:4000 or
11666:5000

 

In the Cisco world, we had to define network statements of our own subnets
and route those blocks to Null0 in order to advertise. I'm thinking
something similar here in JunOS?

 

Thanks for any insight.

 

Paul

 



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