[c-nsp] Cisco MultiLink PPP

[Lawrence Wong]

--- Andre Beck <cisco-nsp at ibh.net> wrote:
> > Any idea how many E1 MLPPP is supported on the
> 2621? I
> 
> The 2621 is quasi-identical to the 2620. I have
> first hand experience
> with trying to upgrade a 2xE1 MP bundle on such box
> to 3xE1. It did
> work in principle, but the CPU load on this box
> reached peaks beyond
> 60% when that bundle got fully loaded with traffic.
> This caused an
> unusual amount of RTT jitter and response loss on
> pings to that router
> what finally convinced us to give up the MP and
> retry with CEF load
> sharing per-packet. The box has 15 to 20% less CPU
> load this way.
> 
> However, keep in mind that this was with a late
> 12.1, not really a
> recent IOS. As already pointed out by others here,
> newer IOSs can do
> MP CEF switched, so the numbers might be better
> there. This is something
> I'd actually want to lab test soon as I'd really
> like to get back to MP
> there if possible.

Do let us know how things go if you get to test out in
your lab. It sure will be fun to see how much "soft"
engineering advanced over the versions.

> > don't think I will grow beyond 2 channels but if I
> 
> Two channels is working great. You get all the
> advantage of MP including
> perfect load balancing, guaranteed no reordering and
> load balancing of
> IP multicast (something I can't stop repeating you
> *don't* ever get with
> CEF per-packet).

That's one thing I like about MLPPP over others like
per packet load sharing, etc.

> > need to replace the 2514, it would be on the safe
> side
> > to cater for 3-4 E1 MLPPP just in case (would a
> 3620
> > be good enough?) .
> 
> Forget 3620. Rather consider the newer 26xx models

I was thinking if the 3640s on used market will do the
trick? Looks like more powerful than the 3620.

> or even 18xx/28xx. They
> aren't even really expensive compared to former
> gear. If ever going 3k
> series, rather consider 37xx or 38xx, with exception
> for the 3660.

The 37xx & 38xx looks very overkill for my "warehouse
to headoffice" connectivity. I was thinking of the
1841 but the Cisco brochure at
http://www.cisco.com/application/pdf/en/us/guest/products/ps5853/c1244/cdccont_0900aecd801738fa.pdf
says it's more capable of maxing out a 2Mbps link but
no mention of 2 x 2 or 3 x 2. Anyone played with these
new kids on the block yet?

> > I am thinking of using the VWIC-2MFT-G703 module
> on
> > the 2621 to connect the individual links instead
> of
> > getting external v.35 convertors.
> 
> Do you *really* need unframed E1? It's the only
> additional virtue of the
> -G703 over the -E1 and surely not worth the
> significant price step except
> you must have it. You can even stamp a G.704 frame
> onto a line that is
> provided unframed, so the only reason you must have
> unframed is when
> talking to a remote CSU/DSU that is limited to
> unframed either by design
> or by not beeing under your control.

I guess I need the G703 cos that's what the telco
drops in my lap.

> > Anyone has experience with it?
> 
> So far only with the -E1. Work like a charm. We've
> got several 26xx
> (including 2620) packed with those VWICs and they
> are doing great.
> For proper MP operation with 2xE1 and CBAC we prefer
> the 2650 class,
> but otherwise a 2620 can well deal with 4 individual
> E1 interfaces at
> full load without a tendency to fall over.


When running your bundles, are you running other
features like CBAC, NAT, etc that may increase CPU
overheads?


Thanks,

> HTH,
> Andre.
> -- 
>                   The _S_anta _C_laus _O_peration
>   or "how to turn a complete illusion into a
> neverending money source"
> 
> -> Andre Beck    +++ ABP-RIPE +++    IBH Prof. Dr.
> Horn GmbH, Dresden <-
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