[c-nsp] PPP Multilink

[Tim Franklin]

> The point here is, 
> CEF LB works great if you have multiple links, even with voice.
> So why add a multilink overhead and run buggy 'cef over multilink' 

* Single L3 interface - for me this is very helpful in terms of management,
YMMV.
* A single flow can use all the link bandwidth - with CEF LB this doesn't
work without per-packet, and that brings its own issues.
* QoS - you can put an MQC config on the single multilink interface, and it
correctly divides the aggregate bandwidth up amongst the classes.  You can't
do this with CEF LB - even if you put the policy map on every interface, you
can't guarantee that you won't get all your LLQ traffic on one link and all
your best-efforts traffic on another.  (Again, per-packet makes this a bit
more workable, but see above.)


It is very much horses for courses - for simple Internet access services,
where the termination is on a platform with known MLPPP issues (7500 in my
case), CEF LB is good enough and we use it.  For managed IPVPN, terminating
on a different access box (with which I don't see any CEF MLPPP issues), and
where the above points become a lot more important, MLPPP makes more sense
to me.

Regards,
Tim.

-- 
____________   Tim Franklin                 e: tim at colt.net 
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