different Inter -AS type on the same 7609S MPLS ASBR router

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May 30th, 2009
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We have 7609s as ASBR for inter-AS in MPLS CORE, can we have this router to have many inter-AS types like A,B,C and AB on the same router for different carriers, or since it is different Inter-AS type need to be in different routers.

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Giuseppe Larosa Sat, 05/30/2009 - 08:58
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Hello Ahmed,

option A can coexist with option B because option A requires back to back connections in each VRF.

Option A:

The ASBR PE needs to configure one VRF and one VRF access link for each VPN that needs to be extended to other provider.

The limit is the max. number of logical interfaces that can be created on the node (given by IDB limit it should be roughly 4096 for 7609)


see


https://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_tech_note09186a0080094322.shtml#max_no_vlans



Option B puts pressure on memory usage on PE -ASBR because they need to exchange VPNv4 prefixes and labels for each VPN to be extended.


Option C: moves the VPNv4 signalling on Route reflectors using VPNv4 eBGP sessions with multihop (and these need to be different nodes) the ASBR PEs exchange routes related to all PE loopbacks and have to build and mantain LSPs with destination the PE loopback addresses.


For effective option C you need to deploy a RRS that will have eBGP VPNv4 sessions with selected carriers.


on the c7609 option A, B can coexist with the PE looopback addresses info for option C


Hope to help

Giuseppe


saeedbakh Sat, 05/30/2009 - 10:26
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Hi,

do you mean that Option A and B can exist on the same ASBR but option C can not be with them on the same ASBR

Giuseppe Larosa Sat, 05/30/2009 - 10:41
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Hello Ahmed,

no I think the same ASBR node can handle option A, B, and C but option C requires an additional node that acts as RR Server.


Hope to help

Giuseppe


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