[c-nsp] Load-balancing T1s on a Cisco 7600

[Patrick Coppinger]

in a similar situation we had to add both of the following:

mls ip cef load-sharing full
mls flow ip full

At 12:10 PM 7/26/2005 -0700, Ian Cox wrote:
>At 01:47 PM 7/26/2005 -0500, Cory Ayers wrote:
> >We recently upgraded multiple Cisco 7200s serving as aggregation routers
> >to Cisco 7606s.  We found that ip load-sharing per-packet with CEF was
> >not an option due to the distributed architecture of a 7600.  We
> >attempted to use MLPoFR and MLPoATM, but neither of these worked, so we
> >opened a TAC case.  We were told that multilink PPP isn't going to work
> >on the 7600 and were advised to have our telephone company bundle the
> >circuits for us and hand us a single PVC.
>
>MLPPP and MLFR is supported on channelized and clear channel T1/E1s.
>MLPPP over ATM and MLPPP over FR is only supported on  single link in
>the bundle for LFI purposes. These features are only supported on
>FlexWAN/Enhanced FlexWAN and SIP-200. They are not supported on the
>OSM-2OC12-ATM-MM+.
>
> >  This is not a valid option as
> >it would affect 500 end-sites and mean dealing with nearly 30 different
> >telephone companies.  Our other option appears to be to remove the Cisco
> >7600s that we recently purchased in favor of a non-distributed
> >architecture.
> >
> >Currently, we have both Frame-to-Frame and Frame-to-ATM terminating on
> >the 7600.  The Frame-to-Frame circuits terminate on a PA-T3+ housed in
> >an Enhanced FlexiWAN.  Multiple DS3 and OC-3 ATM circuits terminate on
> >an LS-1010 and are fed to the 7600 on an OSM-2OC12-ATM-MM+.
>
>If your doing frame to frame then you can utilize MLFR FRF.16 if it
>is FR at both ends.
>FlexWAN
>http://www/en/US/products/hw/routers/ps368/products_configuration_guide_chapter09186a00803f37a8.html#wp84223
>SIP-200
>http://www/en/US/products/hw/routers/ps368/module_installation_and_configuration_guides_book09186a00802109bf.html
>
> >Has anyone successfully configured Multilink PPP over Frame or ATM in
> >this scenario?
>
>Yes on FlexWAN, Enhanced FlexWAN and SIP-200, see the above caveat,
>it is only supported for LFI, not supported bundling links.
>
> >Is there a work-around for CEF load-sharing per-packet that will allow a
> >single flow to utilize multiple T1 circuits?
>
>Is just a single flow, or is the traffic multiple flows between the
>same two IP addresses. If it multiple flows between the same two IP
>addresses then "mls ip cef lod-sharing full" can balance the flows
>based on the L4 information in the TCP/UDP headers.
>
>
>Ian
>
> >Does the Cisco 10000 (ESR) boast similar issues with load-balancing
> >multiple T1 circuits?
> >
> >The Cisco 7200 has been a work horse for us for many years, but lacks
> >the port density, processor, and Gigabit fabric.  We have upgraded to an
> >NPE-G1 in some scenarios, but this doesn't address high density circuit
> >aggregation.  What other routers are people using to fill this need?
> >
> >Thanks!
> >~cayers
> >
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Patrick Coppinger
CCIE #14298
Senior Network Engineer
EarthLink, Inc.