Re: [tlug] Class B Hubs not suitable for data center use?

[Josh Glover <jmglov@example.com>]

Quoth Jean-Christian Imbeault (Thu 2002-08-29 01:05:25PM +0900):
> 
> If I may venture a question, what is the advantage of a hub or switch 
> having buffer memory? (Do hubs have buffer memory?). Is it in case packets 
> are transmitted more quickly than the receive can pick them up? Or is it in 
> case more than one source is trying to send to the same receiver?

Since a hub is a dumb device, buffer memory is probably unnecessary,
as the rate at which incoming packets arrive will almost certainly not
overwhelm the hub's ability to rebroadcast them.

A switch, however, is doing some simplistic routing. IIRC, a switch
maintains an ARP cache to send a packet addressed to a certain IP
address to the port where the ethernet interface having the hardware
address corresponding to that IP address is connected.

Since the switch actually has logic, it is conceivable that it cannot
keep up with the flow of incoming packets. Therefore, most switches
have some memory for queueing packets.

Jonathan, correct me if I made any mistakes. :)


-- 
Josh Glover <jmglov@example.com>

Associate Systems Administrator
INCOGEN, Inc.
http://www.incogen.com/

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