GigabitEthernet Turn up . Question about spanning-tree

[ccoletti]

Hello Everyone,

My customer has two Cisco WS-C3548-XL connected together from the fast Ethernet 0/48 ports at this present time.

My customer wants to shut both fastEthernet 0/48 connections and connect both Cisco WS-C3548-XL from there GigabitEthernet0/1 ports only.

I don’t have a lab to simulate this connection My Question,

Can I let the spantree protocol run its magic or should I intervene with a command line on each Giga port after both Giga ports are activated? Any suggestion would be greatly appreciated

Thank you so very much

[Georg Pauwen]

Hello,

Gigabit has a default cost of 4, while FastEthernet has a cost of 19. That means that STP will choose the Gigabit link over the FastEthernet without you having to configure anything.

Of course it doesn´t hurt to check if it works as expected, but it should...

HTH,

GP

[ccoletti]

Hello GEORG PAUWEN,

I appreciate your update and will monitor the span tree output. Thank you so very much for taking time out to reply to my question.

[amikat]

Hi,

Generally speaking STP will take care. But you should expect recomputations and the final effect really depends on the scale of the network.

Also please be aware that 3500XL supports only 64 STP instances while supporting 250 vlans. So if your network is using more than 64 vlans the upmost care should be taken to avoid loops.

Good luck!

Best regards,

Antonin