North American Network Operators Group

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Re: links on the blink (fwd)

  • From: Vadim Antonov
  • Date: Fri Nov 10 17:57:01 1995

Michael Dillon wrote:

>By "load sharing" I presume you mean some sort of TDM where you have n 
>real lines and every n'th packet goes out on any particular line. I 
>suppose this would be even simpler to do at the byte level if we assume 
>that all n lines go to the same endpoint.

Yep.  However the round-robin load-sharing you described breaks the
sequencing of packets (i.e. they will often arrive in the different
order from which they were sent) and that breaks a lot of TCP stacks
out there.  Cisco's solution is to to do sharing on per-host or per-network
basis (i.e. all packets to host/network go along the same path) which
is, to say, of very little use in the backbone.  It breaks down particularly
spectacularly when you have high degree of aggregation or "calling centers",
i.e. hosts or networks attracting particularly heavy traffic.

I have a simple solution for the sequencing problem in load sharing
setups, which produces load patterns nearly as good as round-robin.
Don't ask how if you're not going to invest :) That algorithm is
central to the proposed hypercube router architecture, and i'm
past the age when i did things just for fun.