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Connecting a 2960g to a 4006

First time poster here and I am stumped!  I have two Catalyst 4006 switches that are on different floors of the same building.  I want to replace one of the switches with a smaller switch, a WS-C2960g-8tcl.  They are connected via fiber.  I was able to connect the new 2960 switch to the Catalyst 4006.  VTP is on for the 4006.  On the 2960 I verified VTP is being received and the VLANs are listed properly.  On the 2960 I assigned ports 1-7 to VLAN 24 port 8 is the SFP.  On ports 1-7 I am not receiving IP addresses.  I turned trunking on and off, no change either way.  Does anyone have any ideas?  I can post configurations if needed.

Thanks,

Michael

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Hall of Fame Super Blue

Re: Connecting a 2960g to a 4006

mgober@crescnt.com

First time poster here and I am stumped!  I have two Catalyst 4006 switches that are on different floors of the same building.  I want to replace one of the switches with a smaller switch, a WS-C2960g-8tcl.  They are connected via fiber.  I was able to connect the new 2960 switch to the Catalyst 4006.  VTP is on for the 4006.  On the 2960 I verified VTP is being received and the VLANs are listed properly.  On the 2960 I assigned ports 1-7 to VLAN 24 port 8 is the SFP.  On ports 1-7 I am not receiving IP addresses.  I turned trunking on and off, no change either way.  Does anyone have any ideas?  I can post configurations if needed.

Thanks,

Michael

Michael

Is the DHCP server in vlan 24 ? If so can you make sure vlan 24 is allowed on the trunk link. If the DHCP server is on a different vlan then where is the vlan 24 L3 interface and does it have an "ip helper-address" command configured.

Can you answer the above and post out of "sh int trunk" from the 2960G.

Jon

5 REPLIES
Hall of Fame Super Blue

Re: Connecting a 2960g to a 4006

mgober@crescnt.com

First time poster here and I am stumped!  I have two Catalyst 4006 switches that are on different floors of the same building.  I want to replace one of the switches with a smaller switch, a WS-C2960g-8tcl.  They are connected via fiber.  I was able to connect the new 2960 switch to the Catalyst 4006.  VTP is on for the 4006.  On the 2960 I verified VTP is being received and the VLANs are listed properly.  On the 2960 I assigned ports 1-7 to VLAN 24 port 8 is the SFP.  On ports 1-7 I am not receiving IP addresses.  I turned trunking on and off, no change either way.  Does anyone have any ideas?  I can post configurations if needed.

Thanks,

Michael

Michael

Is the DHCP server in vlan 24 ? If so can you make sure vlan 24 is allowed on the trunk link. If the DHCP server is on a different vlan then where is the vlan 24 L3 interface and does it have an "ip helper-address" command configured.

Can you answer the above and post out of "sh int trunk" from the 2960G.

Jon

New Member

Re: Connecting a 2960g to a 4006

DHCP is not on the same subnet.  The old 4006 that I am replacing was on Vlan 24 and it was working then.  I also tried manually assigning an IP that is in the VLAN 24 range but to no avail. 

Here are the results from the 2960:

sw7.1#sh int trunk

Port        Mode             Encapsulation  Status        Native vlan
Gi0/8       on               802.1q         trunking      1

Port        Vlans allowed on trunk
Gi0/8       1-4094

Port        Vlans allowed and active in management domain
Gi0/8       1-10,24,32-33,50-54,99-101

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/8       1-10,24,32-33,50-54,99-101

Hall of Fame Super Blue

Re: Connecting a 2960g to a 4006

Can you post config of 2960 + "sh ip int brief" off 2960G.

Also post config from 4006. I'm assuming the 4006 is routing for the vlans ??

Jon

Purple

Re: Connecting a 2960g to a 4006

  On the 2960 ports make sure you have portfast turned on for ports 1-7 .  If you can't statically assign one and get around then the  trunk is most likely not working correctly . If you can post the uplink configs for the 2960 and the config on the 4006 .

New Member

Re: Connecting a 2960g to a 4006

Eureka, I figured it out!  The router module on the 4006 that is being replaced was handling the routing for VLAN 24.  When I looked at the gig interface that I was plugged into I noticed that VLAN 24 was not defined as a sub interface.  I assigned the ports on the 2960 to VLAN 50, which was defined as a sub interface, DHCP and IP traffic began to function.  Now I know that my trunk is working properly.  When I go to decommission the 4006 I will add a Vlan 24 sub interface to the remaining 4006.

Thanks, Jon and Glen for your help I truly appreciate it!

Michael

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