Thousands of hosts on a gigabit LAN, maybe not

Benson Schliesser bensons at
Fri May 8 20:25:32 UTC 2015

Morrow's comment about the ARMD WG notwithstanding, there might be some 
useful context in


> Christopher Morrow <mailto:morrowc.lists at>
> 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 at>
> 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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