nanog mailing list archives

Re: Thousands of hosts on a gigabit LAN, maybe not


From: Benson Schliesser <bensons () queuefull net>
Date: Fri, 08 May 2015 13:25:32 -0700

Morrow's comment about the ARMD WG notwithstanding, there might be some useful context in https://tools.ietf.org/html/draft-karir-armd-statistics-01

Cheers,
-Benson

Christopher Morrow <mailto:morrowc.lists () gmail com>
May 8, 2015 at 12:19 PM

consider the pain of also ipv6's link-local gamery.
look at the nvo3 WG and it's predecessor (which shouldn't have really
existed anyway, but whatever, and apparently my mind helped me forget
about the pain involved with this wg)

I think 'why one lan' ? why not just small (/26 or /24 max?) subnet
sizes... or do it all in v6 on /64's with 1/rack or 1/~200 hosts.
John Levine <mailto:johnl () iecc com>
May 8, 2015 at 11:53 AM
Some people I know (yes really) are building a system that will have
several thousand little computers in some racks. Each of the
computers runs Linux and has a gigabit ethernet interface. It occurs
to me that it is unlikely that I can buy an ethernet switch with
thousands of ports, and even if I could, would I want a Linux system
to have 10,000 entries or more in its ARP table.

Most of the traffic will be from one node to another, with
considerably less to the outside. Physical distance shouldn't be a
problem since everything's in the same room, maybe the same rack.

What's the rule of thumb for number of hosts per switch, cascaded
switches vs. routers, and whatever else one needs to design a dense
network like this? TIA

R's,
John


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