From: Zealist Hamamd (zealist@gmail.com)
Date: Sat Aug 16 2008 - 21:30:12 ART
Hi experts,
It might be silly ques but i m askin :)
I was practicing "BGP Bestpath Selection - Weight*"* Lab in IE Tech
workbook for BGP.
While doing that i noticed that If u ping or trace routes learned via BGP
and when no other protocol is running u must have to do that with source add
of an interface also advertised in BGP other wise it wont work. while in
other protocols if u have a route in ur routing table u can ping it anyway.
So why is this behavior is in BGP?? or it is commone for for all protocols??
Also
topology is this R1,R3 r in AS1 and R4,R5 in AS2
R1-->R3 ibgp ------ R3-->R5 ebgp --- R5-->R4 ibgp and R1-->R4 ebgp
now ques is that at R4 there isnt a route for link bw (R1 and R3) and
similarly on R5 and even then when we ping from R3 we get response(if we
give source interface of R3 which is
in BGP). So isn't it be v difficult while we r going to troubleshoot BGP in
real world where there r countless networks?? shld we always consider
next-hop only in routing table??
i m giving output of sh cmds
FOR R1
------------
R1#sh ip rout
Gateway of last resort is not set
155.1.0.0/24 is subnetted, 4 subnets
C 155.1.146.0 is directly connected, FastEthernet1/0
C 155.1.13.0 is directly connected, Serial0/0
B 155.1.5.0 [20/0] via 155.1.146.4, 00:13:45
B 155.1.37.0 [200/0] via 155.1.13.3, 00:11:34
R1#
FOR R3:
--------------
R3#sh ip rou
Gateway of last resort is not set
155.1.0.0/24 is subnetted, 4 subnets
C 155.1.13.0 is directly connected, Serial0/0
C 155.1.0.0 is directly connected, Serial0/1
B 155.1.5.0 [200/0] via 155.1.13.1, 00:20:14
C 155.1.37.0 is directly connected, Loopback0
R3#
For R4:
---------
R4#sh ip rou
Gateway of last resort is not set
155.1.0.0/24 is subnetted, 4 subnets
C 155.1.146.0 is directly connected, FastEthernet0/0
B 155.1.5.0 [200/0] via 155.1.45.5, 00:14:44
C 155.1.45.0 is directly connected, Serial1/0
B 155.1.37.0 [20/0] via 155.1.146.1, 00:09:21
R4#
For R5:
---------
R5#sh ip route
Gateway of last resort is not set
155.1.0.0/24 is subnetted, 4 subnets
C 155.1.0.0 is directly connected, Serial0/0
C 155.1.5.0 is directly connected, Loopback1
C 155.1.45.0 is directly connected, Serial0/1
B 155.1.37.0 [20/0] via 155.1.0.3, 00:08:47
R5#
Regards,
-- zealist@gmail.comBlogs and organic groups at http://www.ccie.net
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