> From: kevin graham [mailto:kgraham@dotnetdotcom.org]
> Can anyone recommend a resource for understanding the current
> architecture of the 7500? I'm only vaguely familar with the
> platform, and digging around on CCO, I keep running into a
> mix of either marketing drivel, clearly dated information, or
> module-specific data that doesn't cover the system as a whole.
>
See "Inside Cisco IOS Software Architecture" by Cisco Press. It provides as
much information about the 7500 switching architecture as you'll ever need.
http://www.ciscopress.com/catalog/product.asp?product_id={44BD9713-382F-48A1
-B113-E4A8D0FF4F22}&session_id={E7C5500C-B296-406A-9CDF-C1A5780D9748}
> On a 7507/7513, is there a bridge between the two cbus's, or
> is it a function of the RSP to tie them together? If cbus
> bandwidth is 1.067gbps, is my understanding correct that even
> just a GEIP and GEIP+ together will destroy the bus (if
> you're lucky enough to get them running full rates)? In
> distributed mode, does the RSP ever get touched for direct
> adjacencies ie. when distributed, would a RSP8 make much of a
> difference at all over an RSP4.
The RSP handles all VIP-VIP or IP-IP or IP-VIP packet switching. The amount
of interVIP switching capacity is MEMD dependent. RSP8 has 8 MB of MEMD,
RSP4 has 2. In general, MEMD exhausts faster than the CyBUS bandwidth. If
the VIP cannot allocate memory from MEMD (the global pool), it buffers
packets in packet memory on the VIP until there is an available MEMD buffer
for the packet. Distributed is a poorly used word here - the switching
decision is distributed, but it is a master-slave bus that relies on the
RSP. The only true distributed switching occurs within the same VIP.
As far as GEIP+ at line rate, expect no more than 800 Mbps based (which is
the max for the VIP4-80). If you have 2 GEIPs, put them on different buses
and upgrade to RSP8. I have GEIPs running at 400+ Mbps on two different
buses with Cybus utilization in the 40-50% range with very little to no
receive side buffering. To check if RSB is taking place, perform a "show
controller vip <slot> accumulators" and you will see what destination
interfaces needed RSB. If MEMD is a problem, try to change all MTUs to 1500
- this will reduce the amount of MEMD buffers for large packets and such
that very rarely get used.
Chris
>
> If someone could point me in the right direction for this,
> it'd be appreciated..
>
> thanks.
>
> ..kg..
>
This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:13:12 EDT