NAP Solutions

Mon Nov 17 17:23:44 UTC 1997

> What does one do when one has an
>N port MPLS switch/router and has filled all N ports with
>traffic?  Consider that each of the N ports will become
>fuller and that there will probably be a desire or
>requirement for N+1 ports with more to come.
>
>The lesson of the Gigaswitches and the ATM counterparts is
>that scaling beyond a single switch is hard.
>
>I don't have an answer, given what I know and can imagine
>about near-term technology

Two answers. Parallelism and bypasses. Vadim is working on the parallelism
idea with his project at pluris.com so we will soon see whether or not this
is a workable approach.

Bypasses are good old-fashioned highway network technology. When the switch
is overloaded (i.e. the cross-bar street network in the city core) divert
traffic around the city (switch) with a bypass. Or in other words, when all
N ports on your switch are getting full, look at the other end of the
circuit going into each port and try to divert some traffic into a bypass
that does not go through the switch. Remember that the switch's backplane
is essentially a backbone network that has been collapsed into a single
box. The scaling problem arises when too much traffic from other networks
wants to go through this one box. Step back and look at the bigger picture
and you will see that there are solutions that do not require chaining
switches together.

Of course a simple private interconnect circuit is the classic and the
simplest form of bypass, but anything which causes traffic to flow through
a different path meets the criteria. Exchange points cannot be designed or
scaled as discrete objects; they exist in the context of the entire network
mesh.

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Michael Dillon                    voice: +1-650-482-2840
Senior Systems Architect            fax: +1-650-482-2844
PRIORI NETWORKS, INC.              http://www.priori.net

"The People You Know.  The People You Trust."
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