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New Member

Trunk between 3560 and 4948 only passes native VLAN traffic

I've tried updating IOSes, etc. but problem remains.

sh cdp neigh (from 4948)

Device ID        Local      Platform    Port ID

MY_4948       Gig1/46    My_3560   Gig0/13

4948 config

Int Gig1/46

switchport trunk encap dot1q

switchport mode trunk

3560 config

Int G0/13

switchport encap dot1q

switchport mode trunk

Native VLAN 1 traffic traverses trunk; VLAN 70 traffic does not.  VLAN works, and setting separate VLAN 70 port on both switches and connecting ports re-establishes traffic between switches on VLAN 70.

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Hall of Fame Super Gold

Trunk between 3560 and 4948 only passes native VLAN traffic

So who's doing the routing?

New Member

Trunk between 3560 and 4948 only passes native VLAN traffic

no ip routing on the 4948.  3560 does the routing.  Can't reach the VLAN 70 gateway interface on the 3560 via the trunk connection from addresses on the 4948 (tested via host machines connected to the 4948 and also set a test VLAN 70 interface on the 4948), but can if I connect the two VLAN 70 interfaces I have set on the 4948 and the 3560 as a workaround.  Other switches trunking to the 3560 trunk normally, so it appears to be something on the 4948 that I'm not aware of.

New Member

Trunk between 3560 and 4948 only passes native VLAN traffic

Found my own answer:  someone had placed a Dell switch between the 3560 and the 4948 switches (creating a local access in the server room).  CDP worked right through the Dell switch, so remotely it was invisible (the two Cisco switches each saw the other as if they were directly connected), but the Dell switch filtered out all tagged frames.  Had to go hand-over-hand to find this.  Wanted to share anyway; maybe will help someone else.

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