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C3750x Trunking

I have 2 C3750x switches in a stack. G1/0/48 is an uplink to core switch1 and g2/0/48 is an uplink to core switch 2. Both ports are trunking all vlans. However, when I do a show inter g1/0/48 and comapre it to show inter g2/0/48, switch 2 in the stach shows 0 bits/sec in the output rate. All traffic goes out through switch 1. I have included the show interface command output in this file. How can I make the traffic go out both g1/0/48 and g2/0/48.

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Hall of Fame Super Blue

Re: C3750x Trunking

rzulueta315 wrote:

I have 2 C3750x switches in a stack. G1/0/48 is an uplink to core switch1 and g2/0/48 is an uplink to core switch 2. Both ports are trunking all vlans. However, when I do a show inter g1/0/48 and comapre it to show inter g2/0/48, switch 2 in the stach shows 0 bits/sec in the output rate. All traffic goes out through switch 1. I have included the show interface command output in this file. How can I make the traffic go out both g1/0/48 and g2/0/48.

If you core switches are connected to each other with a L2 trunk then this is normal because STP has to block one uplink. You can do -

1) if you have multiple vlans then you can "load-balance" across the uplinks ie.

make core1 STP root for all odd vlans

make core2 STP root for all even vlans

you would also want to match up the HSRP active gateway with the same core as the STP root

2) make the interconnect between your 6500 switches a L3 connection which breaks the L2 loop but this may involve some redesign of your network so you can't just do that.

Jon

1 REPLY
Hall of Fame Super Blue

Re: C3750x Trunking

rzulueta315 wrote:

I have 2 C3750x switches in a stack. G1/0/48 is an uplink to core switch1 and g2/0/48 is an uplink to core switch 2. Both ports are trunking all vlans. However, when I do a show inter g1/0/48 and comapre it to show inter g2/0/48, switch 2 in the stach shows 0 bits/sec in the output rate. All traffic goes out through switch 1. I have included the show interface command output in this file. How can I make the traffic go out both g1/0/48 and g2/0/48.

If you core switches are connected to each other with a L2 trunk then this is normal because STP has to block one uplink. You can do -

1) if you have multiple vlans then you can "load-balance" across the uplinks ie.

make core1 STP root for all odd vlans

make core2 STP root for all even vlans

you would also want to match up the HSRP active gateway with the same core as the STP root

2) make the interconnect between your 6500 switches a L3 connection which breaks the L2 loop but this may involve some redesign of your network so you can't just do that.

Jon

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