[ILUG] Delay between link up and forwarding frames?
Gareth 'bigbro' Eason
bigbro at skynet.ie
Sat Jan 10 13:06:43 GMT 2009
Kenn Humborg wrote:
> Turning on 'portfast' works nicely. Thanks!
>> If I understanding it correctly, spanning tree is only needed on
>> switch-to-switch links, so I need to remember to turn it back on
>> if I ever connect a switch to one of these ports. Correct?
> Misunderstanding on my part there. Since I'm not turning off
> spanning-tree, I don't really need to worry.
On the contrary, you seem to have exactly the right understanding.
Spanning-tree is a loop-avoidance technology, and since computers
typically only have one connection to the network, it's unlikely they
can cause a loop. Hence, the 'portfast' directive on Cisco to state that
you are plugging a single, end-point device into a port, so the switch
should not worry about spanning tree for that port. (In the case of
servers with more than one interface, it's at least likely that traffic
will not be switched between the two NICs, so portfast is probably still
If you are plugging a switch into a port, you should ensure that
portfast is NOT configured for that port. You definitely want spanning
tree to be running on any ports that are connecting switches in your
network, to ensure that it can protect you from loops.
Hope this helps.
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