[c-nsp] Understanding 10G line card oversubscription

[Mack McBride]

There is the 4 port group which I believe is the same as a port pair on a 6708. Ie. No free switching.
Based on some comments by Tim Stevenson, the link between the four port group and the fabric asic is 10G
rather than the 16G in the 6708.  But he mentions some of the same chips (metro, r2d2) so the architecture
can't be much different from the 6708.

Then there is the fabric group which is switched locally without going over the fabric.

show asic slot <x>
sh int <interface> capabilities | inc ASIC

Of course a diagram would be really helpful but those usually come with an NDA.

6708 results:

        ASIC Name      Count      Version
             KUMA          2      (3.0)
      METRO_ARGOS          2      (3.0)
    METRO_KRYPTON          2      (3.0)
              SSA          2      (9.0)
             R2D2          8      (2.0)
         TIANGANG          4      (54.0)

Te<x>/1
  Ports-in-ASIC (Sub-port ASIC) : 1,4-5,7 (1)
Te<x>/2
  Ports-in-ASIC (Sub-port ASIC) : 2-3,6,8 (2)

My understanding of the chips is as follows:

R2D2(per port) -> Tiangang (port pair) -> Metro argos -> SSA (Fabric complex)
Metro Krypto interfaces to the EARL complex aka PFC (local switching/routing to avoid fabric)
Kuma acts as a bus bridge (not relevant to fabric switching)

The assumption is that the Tiangang is replace with another chip that can handle
4 ports.  I assume the new FPGA - Metro link is somehow different on the 6716 but
I don't know how.

The 6704 skips the tiangang chips and directly connects the R2D2 to the Metro.

>From a Cisco doc (http://www.cisco.com/en/US/docs/ios/vswitch/command/reference/vs_02.pdf):
    ASIC Name  Count  Version
         KUMA     2   (2.0)
  METRO_ARGOS     2   (2.0)
METRO_KRYPTON     2   (2.0)
          SSA     2   (8.0)
         R2D2     4   (2.0)

Short answer seems to be that the 6716 is basically the same despite claims to the contrary

Mack

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Phil Mayers
Sent: Monday, March 21, 2011 1:51 PM
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Understanding 10G line card oversubscription

On 03/21/2011 06:33 PM, Mack McBride wrote:

> The 6716 is going to have similar limitations but I don't have a good document on how the port asics connect

My understanding is that the 6716 is quite different from the 6708. 
There's no "free" local switching within port groups AFAIK. The 
differences have been discussed on the list before.

>
> If someone can verify the connection method and limitations on the 6716 it would be appreciated.

Do you have specific IOS commands? We've got a few in service.
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