From: Roberto Fernandez (rofernandez@us.telefonica.com)
Date: Wed Sep 27 2006 - 13:37:46 ART
Mohammad,
"Origin" is just one of many other BGP Attributes; each prefix can have
a bunch of them. Attributes carry on important information about
prefixes being exchanged.
"Origin" is the attribute that describes the way the routes first made
it into the BGP process at the Originating Autonomous System. Routes can
make it to the BGP basically trough two ways:
1- Redistribution (Origin gets the ? for incomplete)
2- Network command under BGP configuration mode (Origin gets IGP)
The EGP value would mean it was a route learned via EGP (Protocol used
before BGP)
"Origin" can have any of three possible values:
IGP
EGP
Incomplete (represented by "?")
The link below points towards, a good introductory resource to BGP and
its attributes.
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c
95bb.shtml#origin
Best Regards,
Roberto
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
msaeed@uaeu.ac.ae
Sent: Wednesday, September 27, 2006 12:25 PM
To: ccielab@groupstudy.com
Subject: BGP Question
Hi all,
I advertised 174.1.1.0/24 network in BGP on R1, when I see sh ip bgp
174.1.1.0 on R4 it mentions Origin IGP, can any one tell me why origin
is
IGP when route is advertised and learned via BGP? Both R1 and R4 are in
same AS of BGP.
Rack1R4#sh ip bgp 174.1.1.0
BGP routing table entry for 174.1.1.0/24, version 17
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Not advertised to any peer
Local
174.1.145.1 from 174.1.145.1 (150.1.1.1)
Origin IGP, metric 0, localpref 100, valid, confed-internal, best
Regards,
Mohammad Zahid Saeed
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