WAN technology

Unanswered Question
May 4th, 2009

We are looking for reconfiguring our WAN topology based on the bandwidth and QoS Policy. AT&T as service provider has two access services, MLPPP and ATM service, including IMA.What is the difference between them?

Pros and Cons?

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Joseph W. Doherty Mon, 05/04/2009 - 08:40

One major logical difference is some support for IP based QoS using DSCP markings within MPLS. Another major difference is how your sites logically "see" each other across the provider's WAN cloud. With ATM, you often have dedicated PVCs, site-to-site (logically much like frame-relay). With MPLS you often just eBGP peer with the MPLS provider's edge devices which logically provides multipoint connectivity (much like eBGP with ISPs).


The major pros and cons: MPLS is likely priced to be more attractive and, once you get used to it, perhaps easier to configure. ATM, using defined PVCs, would require more configuration effort, but allows you better control.


Of course, other factors exist. Best choice depends much on what your network requirements are. In general, most, today, would opt for MPLS.

lamav Mon, 05/04/2009 - 11:36

Ken:


MLPPP and ATM IMA are similar in terms of the problem they address. Each one allows you to maximize the existing bandwidth between two points by bundling the physical links together and allowing for load balancing, and as far as MLPPP is concerned, interleaving and fragment-delay.


As for QoS, you can apply a QoS policy to the virtual Multilink interface or the ATM IMA subinterface.


It may come down to the router platform you're running and whether you have the hardware to run either one. It may simply be an issue of cost. As a note, if you want to run frame relay over the IMA, you cant.


I wish I had more, but this is about what I can offer.


I have configured ATM IMA before, but not MLPPP on serial interfaces, just dialer interfaces for ISDN BRI dial backup.


HTH


Victor

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