You might think also to implement MLS (Multi Layer Switching) in your
Catalyst 5500,
after you have followed Peter recommendations.
Sebastien.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Peter Van Oene
Sent: 09 November 2000 00:14
To: [EMAIL PROTECTED]
Subject: Re: Why not supernetting?
Outside of anything more "best practice design" specific which others are
and I'm sure will cover, I would look at your 100 meg downlinks (connections
from edge switches to aggregation switches back to 5500 in increasing order
of importance) Specifically, check to ensure that your duplexes on either
end of the connections are set the same. Futher, look at error counts
(crc's, runts etc) to ensure that these links are performing adequately.
I've seen duplex mismatches cause exactly this type of "tragic" performance
as you describe it.
Peter
*********** REPLY SEPARATOR ***********
On 11/8/2000 at 2:13 PM jeongwoo park wrote:
>Hi All,
>
>I am looking for advice on a LAN performance issue. i
>am running primarily NT4 and win2K boxes on a 100Mbit
>UTP Ethernet LAN.
>
>my servers are on static IPs on one subnet while my
>clients pick up DHCP addresses (assigned out of my
>control) in any one of half a dozen other subnets.
>file transfer and printing performance between client
>and server is averaging 1Mbit/sec when computers are
>in different subnets. switch the same two computers to
>static IPs in the same subnet and throughput jumps to
>a respectable 30-70Mbit/sec. i need to keep the
>clients on DHCP as i don't have enough static IPs to
>go around for the subnet the servers are in.
>
>all clients and servers are attached to one of 5
>Allied Telesyn 8126XL 24-port managed switches. all 5
>of these "edge" switches connect to another switch of
>the same model with a 100Mbit multi-mode (1300
>nanometer) fiber uplink which connects to a Cisco
>Catalyst 5500 for our routing needs.
>
>When the clients are on different subnets the file
>transfers appear to take a long trip through the
>router with a huge performance penalty (1Mbit/sec).
>when the client and server are on the same subnet the
>packets do NOT appear to be routed (perhaps they are
>handled using ARP?) and the performance is very good.
>ping response times on both switches and routers is
>under 20ms. This is where I believe supernetting could
>be a solution to this slowness, because I think
>supernetting allows me to put all stations in the same
>subnet, witch avoids routing needs.
>
>I got some responses to my previous post from people
>saying that supernetting would slow down the speed
>because there would be too many stations in big
>broadcast domain, which contradicts what I am willing
>to do.
>
>Am i missing some key concepts here that might improve
>my understanding of this tragic performance?
>
>
>any help would be greatly appreciated.
>
>take care,
>
>jw
>
>
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