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LACP on C3750 switches

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14 years 1 month ago #35660 by simwintech
Hi,

2 x C3750 switches are interconnected with each other using 2 x fibre optic cables and i want to bind the bandwidths of two ports to 2Gbps using LACP on C3750 switches. Below are the configurations done on both the Cisco switches and LACP is not working, still getting 1 Gbps speed.

Switch A port Gig1/1 is connected with Switch B port Gig1/1
Switch A port Gig1/2 is connected with Switch B port Gig1/2

Switch A:

# Interface Gig1/1
channel-protocol LACP
channel-group 1 mode active

# Interface Gig1/2
channel-protocol LACP
channel-group 1 mode active

Switch B:

# Interface Gig1/1
channel-protocol LACP
channel-group 1 mode active

# Interface Gig1/2
channel-protocol LACP
channel-group 1 mode active

Can anyone help me?
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14 years 1 month ago #35662 by S0lo
Replied by S0lo on topic Re: LACP on C3750 switches
Your config is probably OK. Etherchannel is not strictly round robin load-balancing. In otherwords, Etherchannel does NOT necessarily distribute the load evenly across the aggregated links to utilize the the sum of the bandwidths

As far as I know, Cisco's Etherchannel (in many switch models including the 3750) usually uses information in the frame (like the source/destination MAC address or source/destination IP address) to determine what physical port the frame will be sent through. This is why if your sending from a single host to a single host, it would probably end up using only one port on the switch (thus the 1Gbps).

Try sending from say host A to host B and from host C to host D at the same time. See if that makes a difference.

You can configure the load balancing and forwarding method using the port-channel load-balance command.

You can also find out which interface is used in the EtherChannel to forward traffic based on the load balancing method using test etherchannel load-balance interface port-channel command

Hope this gives a clue.

Studying CCNP...

Ammar Muqaddas
Forum Moderator
www.firewall.cx
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14 years 1 month ago #35663 by Losh
Replied by Losh on topic Re: LACP on C3750 switches
Just to be sure your etherchannel is up,type this command.

Switch#show etherchannel summary

the port channel should be up & with the initials (SU) if its L2.
Then again Solo is right,as usual.

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