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

[Cory Ayers]

> 
> in a similar situation we had to add both of the following:
> 
> mls ip cef load-sharing full
> mls flow ip full

I have added both commands and notice a slight difference with multiple
flows.  For example, I can see a customer running a Peer-Peer
application and it is now balancing to 140K/s, 120K/s, 170K/s across
three T1s.  However, if I open an FTP transfer to a machine it ramps a
single T1 up to max and the other two T1s don't move.  I open a second
transfer (same source and destination) and it continues to use the same
T1 each time.  

I found the following link that says this command is only support on
Sup-2.
http://www.cisco.com/en/US/customer/products/hw/switches/ps708/products_
command_reference_chapter09186a00801026fb.html#wp1152699
I am running a 720-3B, so I'm not even certain this is doing what it
should be.  However, this still doesn't do an efficient job of
load-balancing in my opinion.  Are there any other alternatives?  This
is what I see:

-  Multilink PPP is not an option for Frame or FRF.8.
-  MLFR could work for 15% of our circuits, but we will be transitioning
those to FRF.8 in the near future.
-  CEF load-sharing no longer allows for per-packet balancing.
-  Layer 2 bundling by the telephone company dealing with dozens of
telcos and nearly 500 end sites is not viable.
-  Replace 7600 router with a router capable of per-packet load-sharing,
but ideally would need to support ATM OC-12 interface and multiple
Gigabit interfaces.

Any other ideas?

> 
> 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
_c
> hapter09186a00803f37a8.html#wp84223
> >SIP-200
>
>http://www/en/US/products/hw/routers/ps368/module_installation_and_conf
ig
> uration_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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> > >https://puck.nether.net/mailman/listinfo/cisco-nsp
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> 
> Patrick Coppinger
> CCIE #14298
> Senior Network Engineer
> EarthLink, Inc.
>