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UplinkFast with a loop of 4 switches ?

In a network with a loop build by 2 x Cat4006 and 2 x Cat2950 is it possible to use the uplink fast feature and does it work correctly like in a loop with 3 switches. Is it ok if I configure uplink fast on my both access switches.

In summary is it possible to use uplinkfast in a loop with more than 3 switches?

2 REPLIES

Re: UplinkFast with a loop of 4 switches ?

Yes,

it's possible.

Just be careful about port costs - while mixing 100Mbps and 1Gbps ports especially.

Example:

Enabling UplinkFast increases all port costs by 3000.

It means that 1Gbps port has 3004 cost now and 100Mbps port has 3019 cost now.

So the path consisting of two 1Gbps lines going through UplinkFasted switches has the total cost 6008 which is more than 3019 cost of one 100Mbps line.

Without UplinkFast a path consisting of two 1Gbps lines has total cost 8 which is less than 19 of one 100Mbps line.

I'm using UplinkFast similar your way. All my access switches pairs are connected following way:

A1---A2

|.....|

|.....|

D1---D2

(the ..... are used just to save spaces in the scheme)

Ax are access switches, Dx are distribution switches.

UplinkFast is enabled on all access switches (with the port cost care described above).

Everything works fine.

Regards,

Milan

Re: UplinkFast with a loop of 4 switches ?

Hi, there is also a possibility to use Cross-Stack UplinkFast feature.

See http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/1219ea1/scg/swstpopt.pdf

for details.

Regards,

Milan

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