Subject: Integrating 2 MPLS network

From: "Tsang, Fatima" <[email-masked]>
Date: Tue, 21 Aug 2001 09:43:40 +0800

Dear All,

I am new at this, hope you can provide some assistance.

I have the following situation:

City A, City B, City C
City A and City B are on one unique MPLS network by ISP A
City B and City C are on another unique MPLS network by ISP B

Is there any way that City A can talk to City C via City B through the
router B?  If so, is there anything required to be done on the PE's for this
customer?

Thanks.

Greatly appreciated.

Thanks,
Fatima

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From: Eric Osborne <[email-masked]>
Date: Mon, 20 Aug 2001 22:38:52 -0400

> router B?  If so, is there anything required to be done on the PE's for this

Depends on what the carriers do.  If both ISP A and ISP B are talking
to each other, they could run inter-provider MPLS BGP VPN.  But that
requires a lot to line up between ISP A and ISP B.

Another way to do this is a full mesh of GRE tunnels between cities A, 
B, and C.  Disadvantage is that it's harder to scale to lots of
cities; advantage is that there's nothing the provider needs to do to
let this happen.

eric

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From: "James Luciani" <[email-masked]>
Date: Tue, 21 Aug 2001 13:00:23 -0400

Depending on your assumptions about the underlying networks and address
spaces, taking a routed hop between ISP-A and ISP-B works just fine.  Of
course, if you are playing games with overlapping address spaces in VPNs you
need NAT-like functionality but if all addresses are globally routable you
are fine.