BGP issue

From: Shamin (ccie.xpert@gmail.com)
Date: Wed May 24 2006 - 13:26:24 ART


Hi all,

I am stuck in a problem from the IEWB VER3 LAB-8 Task 4.5. The scenario is
as follows :

                    BB3 (AS 54)
                        |
                    (EBGP) Eth0/0 {174.1.1.1/24}
                        | |
                 R5(AS 65145) ----------- R1(AS 65145 )
-----------(EBGP)----------- R3(AS 65038) -----------(EBGP)---- R2(AS 65267)
                         | |
                         | |
                         |____R4(AS 65145)__|

  The question states as follows :
      1) Advertise 174.1.1.0/24 network into the bgp domain on R1
      2) Devices outside of AS 65145 should not have reachability to this
network
      3) Do not use any access-list or prefix lists to accomplish this.

    The solution provided is as follows on R1 -

      R1#
           router bgp 65145
              network 174.1.1.0 mask 255.255.255.0 route-map LOCAL_AS
              neighbor 150.1.5.5 send-community
           !
           route-map LOCAL_AS permit 10
            set community local-As

Can anyone help me understand the two statements under the router bgp ,
especially the network statement. And what does this Local-As
community actually do. When i configured this in my lab, I was not able to
see the 174.1.1.0/24 network on R3 as required. Why didnt R1 sent the
update to R3 because as per above configurations , I dont see any reason for
R1 not adverstising 174.1.1.0/24 to R3.

Please help me understand the scenario.

Regards
Shamin



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