[c-nsp] WS-X6704-10GE, WS-X6708-10GE

[Saku Ytti]

On (2012-03-06 22:54 +0100), Łukasz Bromirski wrote:

> (on each of it the CFC has to query PFC for decision). The limit
> for such system is 15 or 30Mpps. The limit for DFC system is
> 48Mpps per linecard.

Just to help other people on the list understand where this difference
comes from.
The PFC in DFC and SUP are same, i.e. 48Mpps or so.

But SUP PFC under-performs DFC PFC is because we are unable to send work to
it.

DBUS is 62.5MHz and does 32B per cycle. IPv4 lookups are 2 cycles (64B) and
IPv6 (and MPLS) lookups are 3 cycles (96B).

So 62.5/2 = 31.25Mpps (IPv4) and 62.5/3 = 20.83Mpps (IPv6, MPLS). 

There are many situation where circulation occurs, this will of course
halve the performance. Especially in use of tunnels and L3 MPLS VPN.

(As trivia, as far I understand, there probably isn't technical reason why
SUP couldn't do ~48Mpps of MPLS lookups by sending just 32B of packet,
you'd lose ability to do MPLS ECMP based on IP headers though. But I'm not
at all sure about this)
-- 
  ++ytti