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Thread Index [isp-bgp] Difference in Bgp origin attribute
Hi,
I am observing the difference in origin attribute when i use the
following topologies
Topology1:
---------------
R1 -----
ebgp -------Cisco1---------ibgp--------Cisco2-------ebgp-----R2
AS No of R1 = 100
AS No of Cisco1 and Cisco2 = 200
AS No of R2 = 300
R1 has ebgp connection with Cisco 1. Cisco1 has ibgp connection with
Cisco2. Cisco2 has ebgp connection with R2.
When i import static route Rx in R1, Cisco receives Rx from R1 with
origin as incomplete. Cisco1 sends Rx with incomplete origin to Cisco2 and
cisco2 sends to R2 with same origin.So finally the Rx has incomplete origin
at router R2.
Topology2:
-----------------
R1-------ebgp------Cisco1-------- IGP--------Cisco2--------ebgp-----R2
AS No of R1 = 100
AS No of Cisco1 and Cisco2 = 200
AS No of R2 = 300
BGP and Ospf are enabled in Cisco1 and Cisco 2. Also redistribution from
bgp to ospf is enabled in Cisco 1 and redistribution from ospf to bgp is
enabled at cisco2.
When i import static route Rx in R1, Cisco1 receives Rx with imcomplete
origin. Cisco1 redistributes with the TAG value as 0x90000064 . The same TAG
is sent to CISCO2 ospf. When Rx is redistributed from ospf to bgp in cisco2,
the origin attribute is set as EGP (as per RFC1745). So R2 receives Rx with
origin as EGP from Cisco 2.
So there is a difference in Origin attribute with Topology1 (incomplete)
and Topology 2 (EGP) at Cisco2 and R2.
So anyone can please explain why this difference?
Thanks & Regds,
Sakthi
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