From: Tom Holloway (Tom_holloway@xxxxxxxxxxxxxx)
Date: Thu Aug 02 2001 - 11:29:17 GMT-3
I know it's a bit late to answer this but, remember the switch reads the
frame in before retransmission, there is always a buffering delay creating
latency. If you want to reduce latency in this situation use a
repeater(hub). By using a hub the latency is equal to the propagation
delay. However using bridging technology such as a switch you also have two
propagation delays, one from host to switch and another from switch to host,
this is of course unidirectional, double it up for a round trip. The old
original training materials Cisco has covers this quite well, the new policy
seems to be switching or nothing.
regards Tom
> -----Original Message-----
> From: Troy Edington [SMTP:TEdington@ingenuity.com]
> Sent: Wednesday, July 18, 2001 5:29 PM
> To: Ccie Lab (E-mail)
> Subject: OT: Latency question
>
> Hello Group,
>
> I have a problem I need to solve and it has to do with network latency.
> Specifically I am wondering what are my options in getting latency between
> two machines in the same vlan to around 10 microseconds or less. I know
> latency is a relative term and there are other things that come into play
> like the cpu, memory and actual application, but I am speaking of just the
> network latency. After doing tests with my sniffer and other utilities
> and
> reading up on the issue. The best performance I have seen is around 200
> to
> 300 microseconds or .2 to .3 miliseconds. This is with Fast ethernet and
> UDP or TCP (Both had relatively the same latency within the same VLAN) I
> know in order to get really low latency ethernet and TCP/IP are probably
> not
> going to work for me. I know SNA has extremely low latency, but I don't
> really want to implement that. Any other suggestions or solutions would
> be
> appreciated.
>
> Thanks Group
>
> Troy Edington, CCIE #7190
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