STP with Gig links

[jagdev.dhaliwal]

Hi All,

Is there any diffrence between, the link cost of 3gig and 8 link etherchannel            

100 Mbps 19 Fast Ethernet

200 Mbps 12 Fast EtherChannel

300 Mbps 9 Fast EtherChannel

400 Mbps 8 Fast EtherChannel

500 Mbps 7 Fast EtherChannel

600 Mbps 6 Fast EtherChannel

700 Mbps 5 Fast EtherChannel

800 Mbps 5 Fast EtherChannel

1 Gbps 4 Gigabit Ethernet

2 Gbps 3 Gigabit EtherChannel

10 Gbps 2 10G Ethernet

20 Gbps 1 20G EtherChannel

40 Gbps 1 40G EtherChannel

I found the above information, so not sure if there will be any cost diffrence between 3 Gig and 8 Gig.

Thanks

Jagdev

[Peter Paluch · Accepted solution]

Hello Jagdev,

To be honest, there is only a little chance that the STP port cost of a 3Gbps port would be different to the cost of an 8Gbps port using the so-called short port cost method based on 802.1D-1998.

However, does your switch support the spanning-tree pathcost method long command? If it does, it will activate the port cost method as defined in 802.1D-2004:

100 Mbps ~ 200,000

1 Gbps ~ 20,000

10 Gbps ~ 2,000

etc.

In general, 802.1D-2004 cost = 20,000,000 / (bandwidth in Mbps)

Best regards

Peter

[jagdev.dhaliwal]

Thanks Peter,