LACP and RSTP

[perpaal]

Hi

I want to create a redundant ring topology.

Switch A <-> Switch B

Switch B <-> Switch C

Switch C <-> Switch A

I`m using gigabit interfaces, and want 2Gbps backbone capasaty.

What will be the best setup here?

Thought about using LACP and RSTP, but can they function togheter, or should I only use LACP?

Wery happy if some can explain a configuration example

[cadet alain]

Hi,

These are 2 different protocols.By default PVST+ is the spanning-tree solution enabled on switches to solve L2 loops problem but you can change to RPVST+( Cisco implementation of Rapid STP) or MSTP.

If you want to bundle links  you can use PagP(Cisco proprietary) or LACP or manual bundling.

So RPVST+ and LACP GEC is no problem.

But don't forget  depending on etherchannel load-balancing technique and your traffic flows you may end using only one of the bundled interface and so still max out at  1 Gig.

For configs, take a look here

etherchannels:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.2_25_see/configuration/guide/swethchl.html

STP:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.2_25_see/configuration/guide/swstp.html

Regards.

Alain.

[perpaal]

Thank you.

But don't forget  depending on etherchannel load-balancing technique and your traffic flows you may end using only one of the bundled interface and so still max out at  1 Gig.

Why? Wont it use both interfaces as long as they are up an running?

[cadet alain]

perpaal a écrit:
Thank you.

But don't forget  depending on etherchannel load-balancing technique and your traffic flows you may end using only one of the bundled interface and so still max out at  1 Gig.
Why? Wont it use both interfaces as long as they are up an running?

No load-balancing  algorithms take into effect src-mac or src-ip or src-dst mac or src-dst ip and on some higher end platforms even the TCP/UDP port.

It is platform dependent.  http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml

Regards.

Alain.