02-07-2005 12:32 PM - edited 03-02-2019 09:31 PM
I just took over the net admin pos at this company. On 2924 swtches that are connected to other switches via a FE port spanning-tree portfast is turned on. On a bunch of others it is turned off. Which one is correct?
02-07-2005 12:39 PM
Hello,
on ports connected to other switches, turn portfast off, on user ports, turn it on.
Here is the explanation:
A port configured with portfast skips the listening and learning phases of the spanning-tree protocol, and the port transitions directly to the forwarding state. Since the connected end stations are by definition stub connections, a spanning-tree loop cannot occur on these ports under normal circumstances. In addition to being unnecessary, running spanning-tree on ports that connect to end stations may result in undesirable effects. These effects may include hosts not being able to negotiate addresses through DHCP, or log on to a network domain.
HTH,
GP
02-07-2005 07:21 PM
Thank you for your responce. I found this article this evening that states what you wrote as well.
02-07-2005 12:40 PM
You definitely want it on, especially on switch-to-switch links. On other ports where you know you have devices such as workstations, servers, etc., you can use spanning-tree portfast; that will put the port into a forwarding state faster than if you were using spanning-tree in the default mode.
02-08-2005 06:52 PM
In some cases - turning on Spanning Tree Port-Fast on Layer 3 Links between switches can provide faster convergence. - where your absolutely sure there is no loop -
You can achieve faster network convergence when a switch comes back after a power down.
You have to be very careful - I have always turned on Port Fast on layer 3 point - point links to provide for faster recovery.
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