[179831] in North American Network Operators' Group
RE: Thousands of hosts on a gigabit LAN, maybe not
daemon@ATHENA.MIT.EDU (Chuck Church)
Fri May 8 15:18:39 2015
X-Original-To: nanog@nanog.org
From: "Chuck Church" <chuckchurch@gmail.com>
To: "'John Levine'" <johnl@iecc.com>,
<nanog@nanog.org>
In-Reply-To: <20150508185303.55159.qmail@ary.lan>
Date: Fri, 8 May 2015 15:18:32 -0400
Errors-To: nanog-bounces@nanog.org
Sounds interesting. I wouldn't do more than a /23 (assuming IPv4) per =
subnet. Join them all together with a fast L3 switch. I'm still trying =
to visualize what several thousand tiny computers in a single rack might =
look like. Other than a cabling nightmare. 1000 RJ-45 switch ports is =
a good chuck of a rack itself.
Chuck
-----Original Message-----
From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of John Levine
Sent: Friday, May 08, 2015 2:53 PM
To: nanog@nanog.org
Subject: Thousands of hosts on a gigabit LAN, maybe not
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
