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

[Xu Hu]

Many thanks for your clarification.

Thanks and regards,
Xu Hu

On 14 Jun, 2012, at 7:09, Łukasz Bromirski <lukasz at bromirski.net> wrote:

> 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
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