[c-nsp] VS-S720-10G (6509 VSS Engine) 10G Port Issue

[Łukasz Bromirski]

On 2012-06-13 05:55, Pete Templin wrote:
> On 6/12/12 11:06 AM, Łukasz Bromirski wrote:
>
>> In reality, Sup720-10GE sold with the "VS" prefix is a
>> perfectly normal Supervisor. What is changed is that the
>> fabric matrix is actually 20x20Gbit/s not 18x20Gbit/s, so
>> you get additional 2 channels for 20Gbit/s.
>
> Oh, is that for the 6511 chassis?

6511? Never heard about it.

> 18x20Gbit/s means 2x20Gbit/s per slot * 9 slots, so the Supervisor slots
> already have 2x20Gbit/s feeding them to drive the front-panel ports.
 > Why would they need a 19th or 20th channel?

To drive the uplink (2x10GE) at full speed without oversubscription,
as those are VSL links.

In old Sup720 design, the Supervisor itself is connected to the
fabric using one channel. This channel is used by Hyperion ASIC
to provide for bus interface, and multicast/SPAN features. Because
there's no other way to connect the uplinks on the Sup itself, the
Hyperion has it's interface also terminating the uplinks (2xGE)
thus limiting effective throughput/etc. BTW, both PFC and MSFC
are also connected to the rest of the chassis linecards by Hyperion
(PFC) and Pinnacle (MSFC).

On the Sup720-10GE, the separate, 19th channel is used to connect
the uplinks directly into fabric. Hyperion is still there, it still
takes the channel "belonging" to the slot which Supervisor itself
is in, but thanks to such design doesn't limit in any way
performance you can achieve on the 2x10GE uplinks (or 4xGE). In
the new design, Hyperion takes care of providing connectivity to MSFC3
complex, while Metropolis (ASIC terminating the uplinks and connected
to fabric) takes care of providing transport to PFC3C/CXL.

The 20th channel is used in the same fashion for the redundant
Sup if it's inserted into chassis.

Hope that clears it a bit.

-- 
"There's no sense in being precise when |               Łukasz Bromirski
  you don't know what you're talking     |      jid:lbromirski at jabber.org
  about."               John von Neumann |    http://lukasz.bromirski.net