[nsp] Sup 720

[Lincoln Dale]

Hi Simon,

At 01:09 PM 10/04/2003 +0200, Simon Leinen wrote:
> > on a 6509 chassis, that equates to 8 slots of "dCEF720" modules
> > switching at 25M PPS each (distributed; 8 x 25M PPS = 200M PPS).
> > i'm not sure why the math wasn't done with a 6513 chassis; perhaps
> > just recognition that there's a ton of 6509s out there.
>
>In the 6509, all eight linecards can attach to the 720 Gbps fabric.
>On the 6513, this seems to be true for only five out of 12 slots.

not quite right.
in the 6513, all slots still connect to the crossbars.  its more a case of 
how much bandwidth they have connecting to the crossbars.

in order to explain this, a little bit of background:

  - each crossbar on a cat6k is made up of 16 "channels".
  - on a cat6k with 2 crossbars, there are a total of 32 channels.

the performance of each channel is dependent on the crossbar type.
  - on the older "SFM" crossbar, each channel operates at 8gbit/s full-duplex.
  - on the new "Sup720" crossbar, each channel operates at 20gbit/s 
full-duplex.

on a 6509, the layout of the channels is fairly easy to work out --
16 channels per x-bar across 8 slots = 2 channels per slot (4 channels 
including both x-bars)

on a 6513, the layout is a little more tricky -- you have 16 channels to 
fit into 12 slots.
the layout is that slots 9-13 get 2 channels (4 including both x-bars) and 
slots 1-6 get 1 channel. (2 including both x-bars)

thus:
>At least that's my reading of the White Paper on the three 10GbE
>linecards.  For the new aCEF720 and dCEF720 10GbE cards, it says:
>
>     Slot requirements:
>
>     Can occupy any slot in any Cisco Catalyst 6503, 6506, 6509, 6509
>     NEB, or 6509-NEB-A chassis, or any Cisco 7603, 7606, 7609, or
>     OSR-7609 chassis; Can only occupy slots 9 through 13 in a Cisco
>     Catalyst 6513 or 7613 chassis.

the newer 10GE linecards require lots of bandwidth.  that means they need 
at least 2 channels worth of connectivity to the crossbar.

hope this is helpful.


cheers,

lincoln.