[c-nsp] Cisco 650x sup2 / sup32 configuration - what makes sense?

[Jon Lewis]

On Thu, 8 Dec 2011, Gert Doering wrote:

> The best choice?  Don't use 6148-GE-TX modules.  They are fundamentally
> broken (8 ports share one ASIC with a single-GE uplink, one port that's
> "full" will block out the other 7 ports, ...).  It's even worse if
> you use them for 100M links, because a saturated 100M link will eat
> all the buffers from the other 7 ports on the same ASIC, causing RTT
> jumps on these other ports.

Just to clarify, as I understand it, this (shared buffers) is an issue 
with the 6148-GE-TX, but not with the 6148A-GE-TX, which according to 
cisco documentation has much larger buffers and they're per port, not 
shared by the ports in each 8 port group.  The 6148A-GE-TX is still 8:1 
oversubscribed, so it's a poor choice if you have a need for lots of 
1000baseT ports handling much traffic, but at least it has nice per-port 
buffers.  I suspect if most of the ports are used as 100baseT, and you 
have the occasional 1000baseT port that might carry just a little more 
than 100mbit/s, it should do fine.

----------------------------------------------------------------------
  Jon Lewis, MCP :)           |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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