The MPLS-OPS Archive

["Joe Lin" <jlin@doradosoftware.com>]

I am crossposting this on both cisco-nsp and mpls-ops, since this is a
cisco question yet it is related to mpls :)

I was looking for sample config for Hub and Spoke topology on cisco's
website and I saw some at 

http://www.cisco.com/univercd/cc/td/doc/product/rtrmgmt/vpnsc/mpls/2_0/p
rov_gd/pgmplsa.htm#xtocid152192

I was all excited!!  And also was puzzled that in Cisco-land, you only
need 1 interface for the Hub-PE-to-CE connectivity as oppose to Juniper
where you need two (a spoke instance, and a hub instance).

So I cut and pasted the configs from the link above (instead of Frame
Relay interface, I used Ethernet interfaces), but I couldn't get it to
work :(.   Logically it should've worked.  The only thing I can think of
is that there's something about Frame Relay interfaces that I am
overlooking..

The topology is

!! Topology:
!!
!! CE1---PE---CE2
!!        |
!! CE3----

PE - rsp-pv-mz.120-17.ST3.bin  on Cisco7505 
CE1 - rsp-pv-mz.121-12.bin on Cisco7505
CE2,3 - c7200-p-mz.120-17.ST3.bin on Cisco7200series

The Hub-CE contained routes from both of the spoke CEs, which is
correct.

However, the Spoke-CEs only contain routes of the Hub CE, but not of the
other Spoke CE (CE2, CE3).

I did a # sh ip bgp vpnv4 all on the PE, and a # sh ip cef vrf
VRF_NAME..  the output matched what the CEs were suppose to get.  

Logically thinking, by looking at the configuration, CE1 should've
exported the routes right back out to the spoke route-targets, (CE2,
CE3).  But it just wasn't happening.

I went ahead and create extra import/export statements where all VRF's
imported both route-targets (hub, and spoke), essentially making this a
fully-meshed topology.  

At this point everyone was happy, every CE got their routes!  Which, I
don't understand, because CE1 doesn't know whether it is a hub or spoke
CE router, its job is to send/receive routes.

I even tried OSPF as the PE-CE routing protocol, thinking maybe RIPv2
wasn't cool enough to handle the job..  The same result occurred.

However, I did not try a topology of

!! Topology:
!!
!! CE1---PE---PE2---CE2
!!             |
!!      CE3----|

Where PE is the HubPE, and PE2 is the spoke-PE.

So.. what am I doing wrong?    Can someone send me some cisco configs
that they have tried out that works?

Thanks

-Joe








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