OT: old Ciscos, was Re: [HECnet] Ethernet Marks 40 Years Linking People, Computers in a Wired World

[Peter Lothberg]

  Peter will correct me if I'm wrong here, but the word on the street was
that when the new "flagship" Cisco 7000 was introduced, its routing
performance was lackluster compared to a well-configured AGS+, which caused
some issues with 7000 adoption.   Later 7000-family hardware enhancements
corrected those performance issues.

A cisco 7000 (router) is a AGS+ with Cbus2 painted green..... The SC
is a Cbus controller and it still has a multibus. Tony's silicon
switch engine is a trinary-tree-host-route lookup engine with packet
buffer that replaced the SC..

In 7500 the multibus was finally gone. It still has the Cbus chanel
structure now renabed to CX and later CY bus but now the buffer and
switching is done on the CPU named RSP.. The Mips R4000 is doing
packet switching with a hand-written code path on the 7500.. 

Packets go across the cbus/cxbus twice, in and out and the DMA engine
is on the linecards. The buffer memory is named "memd" and the 12000
is a bigger 7500 with a switch, but it still has "memd" on the RP to
porcess packets to/from the box itself...

-P