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


From: Jima <nanog () jima us>
Date: Fri, 08 May 2015 18:19:04 -0600

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.

     Jima


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