Thousands of hosts on a gigabit LAN, maybe not

Jima nanog at
Sat May 9 00:19:04 UTC 2015

On 2015-05-08 12:53, John Levine wrote:
> 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

  I won't pretend to know best practices, but my inclination would be to 
connect the devices to 48-port L2 ToR switches with 2-4 SFP+ uplink 
ports (a number of vendors have options for this), with the 10gbit ports 
aggregated to a 10gbit core L2/L3 switch stack (ditto).  I'm not sure 
I'd attempt this without 10gbit to the edge switches, due to Rafael's 
aforementioned point of the bottleneck/loss of multiple ports for trunking.

  Not knowing the architectural constraints, I'd probably go with 
others' advice of limiting L2 zones to 200-500 hosts, which would 
probably amount to 4-10 edge switches per VLAN.

  Dang.  The more I think about this project, the more expensive it sounds.


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