Re: MPLS EIGRP backdoor links - SoO

Hi Tom,

I don't believe backbone routers running EIGRP will have the SoO attribute. The doc is talking about EIGRP running on the PE-CE side. The SoO attribute is copied into EIGRP topology table of EIGRP running in the customer VRF.

Cheers,
Ben.

From: Tom Kacprzynski <tom.kac_at_gmail.com<mailto:tom.kac_at_gmail.com>>
Reply-To: Tom Kacprzynski <tom.kac_at_gmail.com<mailto:tom.kac_at_gmail.com>>
Date: Wed, 2 Nov 2011 07:24:40 +1100
To: Christian Hunter <stasis416_at_gmail.com<mailto:stasis416_at_gmail.com>>
Cc: Cisco certification <ccielab_at_groupstudy.com<mailto:ccielab_at_groupstudy.com>>
Subject: Re: MPLS EIGRP backdoor links - SoO

Hi Christian,
Thanks for responding. I'm reading this section from the doc you attached
http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/s_mvesoo.html#wp1049740

*"**When an EIGRP routing process on the PE router redistributes BGP VPN
routes into the EIGRP topology table, EIGRP extracts the SoO value (if one
is present) from the appended BGP extended community attributes and appends
the SoO value to the route before installing it to the EIGRP topology
table. EIGRP tests the SoO value for each route before sending updates to
CE routers. Routes that are associated with SoO values that match the SoO
value configured on the interface are filtered out before they are passed
to the CE routers. When an EIGRP routing process receives routes that are
associated with different SoO values, the SoO value is passed to the CE
router and carried through the CE site. "*

So if you have two backbone routers that don't run BGP, only EIGRP, how
would they actually get a route with SoO attached so they could check if
that route isn't a feedback from the same Site?

(ASCII topology below)

CE-----PE---MPLS---PE------CE
-| |
-|--------------backdoor------------|

Thanks

Tom

On Tue, Nov 1, 2011 at 3:08 PM, Christian Hunter <stasis416_at_gmail.com<mailto:stasis416_at_gmail.com>>wrote:

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/s_mvesoo.html

See the section on "Verifying the Configuration of the SoO Extended
Community"

SoO is a BGP ext community and is set in BGP. When EBGP is used between PE
& CE the SOO attribute is configured via a route-map.. For other routing
protocols the SoO attribute can be applied to routes learned through a
particular VRF instance during the re-distribution into BGP.. I don't
think the IGP has any knowledge since it's just a BGP ext. community that
is used for loop prevention.

Hope that helps.

Christian Hunter

On Tue, Nov 1, 2011 at 3:14 PM, Tom Kacprzynski <tom.kac_at_gmail.com<mailto:tom.kac_at_gmail.com>> wrote:

Hello,
I'm working on a lab using EIGRP as the protocol for MPLS VPN. This
scenario has a backdoor link. I'm testing the Site of Origin feature, but
can't seem to find any way to check the actual SoO on the CE router using
EIGRP commands. Does anyone know how/if I could do that?

I can see it in BGP table but how do I see it in EIGRP

Rack1R6#sh ip bgp vpnv4 rd 100:1 155.1.67.0/24
BGP routing table entry for 100:1:155.1.67.0/24, version 338
Paths: (1 available, best #1, table VPN-A)
  Advertised to update-groups:
        1
  Local
    0.0.0.0 from 0.0.0.0 (150.1.6.6)
      Origin incomplete, metric 0, localpref 100, weight 32768, valid,
sourced, best
      Extended Community: SoO:100:60 RT:100:1
Cost:pre-bestpath:128:28160 <----------------------
        0x8800:32768:0 0x8801:10:2560 0x8802:65280:25600 0x8803:65281:1500
      mpls labels in/out 22/nolabel(VPN-A)

Thank you,

Tom

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Received on Wed Nov 02 2011 - 09:02:07 ART