From: Omkar Tambalkar (omkar.groupstudy@gmail.com)
Date: Mon Nov 03 2008 - 03:28:51 ARST
when you do a debug ip packet detail, you can see the source/destination IP
address of the BGP packets going to TCP 179, if you are not getting a
response from the other side or you are getting a reply from the physical
interface IP address with TTL 0 then you know that your BGP packet is being
dropped by the neighbor before reaching the loopback address.
-HTH - Omkar
On Sun, Nov 2, 2008 at 9:12 PM, omar parihuana <omar.parihuana@gmail.com>wrote:
> Hi GS,
>
> Here the scenario:
>
> One router called router R1and other router R2, R1 belong to AS100 and R2
> belong to AS200 both directly connected. I need to establish an eBGP
> between
> R1 and R2 using loopback interfaces. I have the R1's looback (1.1.1.1) and
> I
> can pinging from R2's loopback (2.2.2.2) and viceversa too. However, I
> cannot see the R2 and R1 configuration only show and debug commands (no
> included sh run) are allowed.
>
> R2#ping 1.1.1.1 source 2.2.2.2
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
> Packet sent with a source address of 2.2.2.2
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 4/137/236 ms
> R2#
>
> R2#sh ip bgp summary
> BGP router identifier 2.2.2.2, local AS number 200
> BGP table version is 8, main routing table version 8
> 1 network entries using 117 bytes of memory
> 1 path entries using 52 bytes of memory
> 2/1 BGP path/bestpath attribute entries using 248 bytes of memory
> 0 BGP route-map cache entries using 0 bytes of memory
> 0 BGP filter-list cache entries using 0 bytes of memory
> BGP using 417 total bytes of memory
> BGP activity 4/3 prefixes, 4/3 paths, scan interval 60 secs
>
> Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down
> State/PfxRcd
> 1.1.1.1 4 100 0 0 0 0 0 never Idle
>
> The same results as above from R1 as well. The question is: what
> configuration is missing in both routers in order to establish an eBGP
> session. After tried some isolate test the missing configuration is:
> neighbor x.x.x.x ebgp-multihop 2. where x.x.x.x is the loopback respective.
> However, my question is: what show command or debug command permit me to
> know that eBGP is missing: I typed the follow debug commands (in both
> routers) without success:
>
> R1#sh debugging
> IP routing:
> BGP events debugging is on
> TCP:
> TCP special event debugging is on
> TCP Packet debugging is on
>
> And it wasn't possible for me to determine what ebgp-multihop was
> missing...
>
>
> Maybe since that BGP state is idle, should I think that is ebgp-multihop
> issue?
>
> Rgds.
>
> --
> Omar E.P.T
> -----------------
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