Inter-exchange media types

Tue Apr 30 16:09:26 UTC 1996

Dtatacom tests were performed in the 10/100 setup. Obviously
the Fast ethernet switches had an advantage over the FDDI
switches since Fast ethernet and conventional ethernet work
with the same frame types. FDDI switches on the other hand
has to convert ethernet frames to FDDI frames and vice versa.
Todays NAPs in most cases are not 10/100 set up. It is more like
DS3/100/100 setup where routers are feeding traffic into the Gigaswitch
using FDDI and since HSSI and FDDI is using same MTU size, no
fragmentation is involved. 

       --Ismat 			

On Sun, 28 Apr 1996, Hank Nussbacher wrote:

> 
> On Thu, 25 Apr 1996 12:34:25 -0400  Curtis Villamizar wrote:
> 
> >For many products, there is a big difference between how many
> >interfaces physically fit in the card cage and how many actually work
> >under a fairly heavy load.  Have you tested a 12 port switched 100
> >Mb/s ethernet under load?  The DEC gigaswitch has been tested under
> >load and has held up so far under load.  The Cisco 5000 may bridge
> >better than it routes since there is no route change to deal with, but
> >I'd be a bit worried about deploying without stress testing.
> >
> >The problem for the major exchanges may soon be what to do when the
> >gigaswitch runs out of bandwidth.
> >
> >Curtis
> >
> 
> The Feb 1996 issue of Data Communications ran a benchmark on these switches
> along with a few others.  I will just summerize the Digital and Cisco info
> that they state:
> 
> Cisco Catalyst 5000 - Full duplex Ethernet, half duplex FDDI, full duplex fast 
> Ethernet; Max: 96 Ethernet, 4 FDDI, 50 Fast Ethernet; Price: $22K for chassis, 24 
> Ethernet ports, 2 FDDI
> 
> Digital Gigaswitch - Ethernet, Full Duplex FDDI; Max: 12 Ethernet, 8 FDDI; Price: 
> $21K for chassis, 24 Ethernet ports, 2 FDDI
> 
> Benchmarks:
> 
> a) % of frames delivered without loss (100% load on 40 ports):
>    Burst size (in 64 byte frames)
>    24: Cisco 99%   DEC 76%
>    62: Cisco 100%  DEC 75%
>    124: Cisco 100% DEC 65%
>    372: Cisco 100% DEC 51%
>    744 Cisco 100%  DEC 49%
> 
> 
> b) % of frames delivered without loss (64 byte frames, 24 frame bursts on 40 ports):
>    70%: Cisco: 100%  DEC: 81%
>    80%  Cisco   99%  DEC  79%
>    90%  Cisco   99%  DEC  85%
>    100% Cisco   99%  DEC  75%
>    150% Cisco   99%  DEC  22%
> 
> c) Per port thruput: 64 byte frame per second (24 frame bursts on 40 ports)
>    Cisco: 4891 
>    DEC:   4391
> 
> d) Latency (microseconds) - 64 byte unidirectional traffic across 100Mb backbone
>    Cisco:  79
>    DEC    179
> 
> Bottom line: The Gigaswitch performed the  almost the worst (Fibronics took that 
> honor) and the Cisco performed the best.
>    
> Perhaps it is time to revisit the Gigaswitch technology?
> 
> ----------------------------------------------------------------------
> Hank Nussbacher                  Manager, Internet Technology Programs
> Telephone: +972 3 6978852        Vnet:     HANK at TELVM1
> Fax:       +972 3 6978115        Internet: hank at ibm.net.il
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