2960 switch has 2 connections to a 3750G switch

[scmacleod]

Hi

I recently started with a new company and the network configuration is like this.

1 - Catalyst 3750G

6 - Catalyst 2960

The 3750 has to connections to the 2 gigabit ports on each of the 2950s. What would be the purpose of this? Is it beneficial?

Any information is much appreciated.

[glen.grant]

More than likely running etherchannel for added bandwidth . Do a "show ether summ" and see if they have etherchannels configured. This will give you 2 gigabits of load balanced bandwidth to play with .Traffic is sent down one link or the other depending on how the etherchannel is setup , it will use either source or destination mac address or source or destination ip address or source and destination address to determine which link the switch sends the traffic down. Realistically if it is a 2950 2 gig uplinks are probably overkill but you would have to look at the utilization of the switch and uplinks useing the "show controllers utilization" .

[scmacleod]

Thank you for the info.

I ran the show ether summ command on all my switches, but I wasn't really sure what I should be looking for. Here is what I got.

4 of the 2960's showed this output:

Switch1>show eth sum

Number of channel-groups in use: 1

Number of aggregators: 1

Group Port-channel Protocol Ports

------+-------------+-----------+------

1 Po1(SD) -

4 2960's showed this output:

Switch5>show eth sum

Number of channel-groups in use: 0

Number of aggregators: 0

Group Port-channel Protocol Ports

------+-------------+-----------+------

1 2960 showed this output:

Switch9>show eth sum

Number of channel-groups in use: 2

Number of aggregators: 2

Group Port-channel Protocol Ports

------+-------------+-----------+-----

1 Po1(SD) -

2 Po2(SD) -

And finally the 3750G showed this output:

switch10>show eth sum

Number of channel-groups in use: 6

Number of aggregators: 6

Group Port-channel Protocol Ports

------+-------------+-----------+-----

1 Po1(SD) -

2 Po2(SD) -

3 Po3(SD) -

4 Po4(SD) -

5 Po5(SD) -

6 Po6(SD) -

[ahmet-saat]

As glan said, it should be for failover and/or load balancing.

And check this out.

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_white_paper09186a0080092944.shtml

This link explains basically Cisco Ether Channel Theory. Probably your configuration is kind of this.