Subject: How manual configuration is done for sham link

From: "nabendu das" <[email-masked]>
Date: Wed, 05 May 2004 20:05:53 +0530

HI

Cosidering the scenario below, how data packets will be forwarded
through sham link

H1 
------------CE1----------PE1-----------P---------------P-------------PE2--------------CE2

A) AUTO-configuration:
PE1 will distribute its sham link endpoint address(10.1.1.1) at PE1 as 
VPN-IPV4 route through BGP along with BGP next-hop and label L1. So PE2 will 
have a routing entry at its VRF for 10.1.1.1 with BGP next-hop and label. So 
while forwarding packet to H1, it will find 10.1.1.1 as next-hop and for 
10.1.1.1 it will find the BGP next-hop and ..it will find the tunnel to that 
BGP next-hop and packet can be forwarded through the tunnel after 
encapsulating the packet with L1 and tunnel first next-hop label.

B) MANUAL configuration:
PE1 and PE2 both will be configured with sham link endpoint address as 
10.1.1.1 and 10.2.2.2 ..
But there will be no route at PE2 for PE1 endpoint address i.e 10.1.1. (as 
we are manually configuring, VPN-IPV4 route for 10.1.1.1 will not be 
advertised via BGP to PE2).... So when we do manual configuration for sham 
link , how sham link will be up and how data packets will be forwarded 
through sham link ???????

TIA
Nabendu

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From: Anand Oswal <[email-masked]>
Date: Wed, 5 May 2004 07:52:02 -0700 (PDT)

Hi,

The sham link end point will be  a  loopback interface (usually)
associated with your VRF.
For manual config you will need to explicitly specify the endpoint
for the sham link.

You can use BGP to carry this address to the remote PE VRF.

So in your example below.
on PE1, you will have a manual config to specify
10.1.1.1 sham-source 
10.1.1.2 sham-endpoint

Hope that helps.
Thanks
Anand