[j-nsp] Circuit Emulation over MPLS

[Richmond, Jeff (ELI)]

I'll just touch on some highlights to keep this brief. First, as I am sure you are aware, ATM has some significant overhead. However, it is very solid for circuit emulation services. Typically your ATM switch will have a port that can be set for CES, and then you'll build a CBR VC to the remote side CES port. If you have an existing ATM network, this is a very doable solution, and we use it quite frequently on our network. 

However, going forward we have moved to an MPLS solution for carrying not only Circuit EM traffic, but ATM traffic as well. Right now I am using mostly CCC connections for carrying ATM and other L2 traffic, but standard MPLS L2VPNs are in the works as well. I prefer the MPLS solution for a couple of reasons. First, ATM is a technology that has been on its way out for a while, and we are not investing in it any further. Secondly, MPLS gives us a lot of flexibility when deploying new services. With LSPs built between PE routers, we can easily provision any type of MPLS VPN technology with just a few keystrokes. I can also pick up any L2 port type and build a VPN, which is advantageous for customers wanting a P2P VPN, but not wanting to run FR or ATM on their CE equipment. 

Now, for Circuit Em with MPLS, you typically would need a device front-ending your router to do the TDM to MPLS/IP conversion (or simply TDM to Ethernet VLANs as another option). Take a look at Juniper's CTP product line or there are other 3rd party vendors as well.

Also, keep in mind that with routers doing MPLS you are also going to need to set up COS functions to protect the circuit-based traffic. This is pretty simple as well, but is a critical piece to making sure you are getting the expected performance end-to-end.

Hope this helps. Feel free to contact me offline for config snippets if you'd like.

-Jeff


-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net
[mailto:juniper-nsp-bounces at puck.nether.net]On Behalf Of Sasanka Bella
Sent: Tuesday, February 14, 2006 2:04 AM
To: juniper-nsp at puck.nether.net; cisco-nsp at puck.nether.net
Subject: [j-nsp] Circuit Emulation over MPLS


Hello,

We are in the process designing a global enterprise network. One requirement
is to have PABX interconnectivity where  each remote PABX need to be
connected to central group switch on ISDN PRI over the WAN. The WAN will be
;

a) either MPLS (L3) over ATM (L2)
b) or, IP/MPLS (ethernet)

We would like to understand the better approach (a or b above) to do ciruit
emulation of ISDN PRI

Can you please share with us ;

1. Advantages/disadvantages of selecting one scenario over the other in
light of circuit emulation
2. Any general issues/concerns with ciruit emulation
3. Any documentation or pointers highlighting how we can achive this
(configuration)

Appreciate very much your comments/inputs on this.

Best regards
SB
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