Fast Link?

Question

Hi all, currently on our 6248 switches we don't have fast link enabled but do use STP. can anyone one give a rough estimate how much improvement there would be in a link connecting if i turned this feature on? i know this might be hard to tell but any estimate would be good many thanks Nigel

drgnslyr · Answer

A good estimate is that it will take the STP (30 to 45 seconds) with fast link should go from Blocking to forwarding almost immediately(under 5 seconds at least) but then again, only want to do this on edge devices and not other layer 2 devices.   hope this helps

NigelRobson · Answer

why only on edge devices? what do you mean by edge? last year we added Exchange 2003 to our network and i was having issues with it. when it booted some of the Exschange services would not start and had to be done manually. when i enabled fast link on this port the problem disappered Nigel

drgnslyr · Answer

edge devices: computers, servers printers. you want them in portfast or fastlink state to keep them from timing out with certain applications.     you are on the right road with fast link .

NigelRobson · Answer

great - i was hoping you would say computers. so by enabling this i would think boot time of PCs on our domain would improve too, as the network would be found and connected quicker. would you agree?

sentinel-master · Answer

The ability for the network switch to forward "user traffic" from your client PC or host sooner than 45secs which is standard spanning tree (L2 switch sequence of device contect : learning -> listening -> forwarding).

By using fastlink (or also known as portfast) you skip the learning, listening stages and hence speed up access to the network.

Caveats : Only use for PC ,Server device........not meant for router --> switch, or switch --> switch conenctions, because you could cause a broadcast storm. In normal SPT stages the port would "listen" for BPDU's (Bridge Protocol Data Units) to ensure a loop free topology - and only going into forwarding mode if safe to do so.

Hence must be a PC or server - as you are the decision point now !!

As long as you PC/Server IP stack and application build are well organised you sholud be able to access the netwotk straight away.

Networking General

Fast Link?

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