10-27-2006 04:27 AM - edited 03-05-2019 12:29 PM
Hi,
I have a 3750G-24T connected to a C3550-48.
VLAN trunking has been setup on the 3550 switch, but on the 3750G, I cannot see the configured VLANs that the rest of our network sees. All I can see is the default vlan info. I have done this a gazillion times before, so I don't know what I have missed this time....
Here is the config:
c3750G
interface GigabitEthernet1/0/1
description Connected to *** port fa0/29 c3550
interface Vlan2
ip address 10.250.1.42 255.255.255.0
no ip route-cache
!
ip default-gateway 10.250.1.254
ip classless
ip route 0.0.0.0 0.0.0.0 10.250.1.254
C3550
description Connected to 3750-24G switch ***
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
interface Vlan1
no ip address
!
interface Vlan2
description backbone network
ip address 10.250.1.13 255.255.255.0
ip helper-address 10.250.1.50
no ip redirects
no ip route-cache cef
standby 5 ip 10.250.1.254
standby 5 preempt
!
interface Vlan3
no ip address
!
interface Vlan4
ip address 10.250.4.251 255.255.255.0
no ip redirects
standby 10 ip 10.250.4.254
standby 10 preempt
standby 10 authentication ***
!
interface Vlan10
ip address 10.250.2.254 255.255.255.0
!
interface Vlan11
no ip address
10-27-2006 04:32 AM
interface GigabitEthernet1/0/1 on the 3750 is not configured as a trunk.
If you want it to be a trunk, which I assume you do, try;
interface GigabitEthernet1/0/1
switchport trunk encapsulation dot1q
switchport mode trunk
Hope this helps
10-27-2006 04:38 AM
d-fillmore,
By default, aren't all ports set to dynamic desirable? And if so, wouldn't the 3750 negotiate a trunk with the other switch? Since the original poster didn't post that part of the config, I assumed it was left as default. If that's not the case, I apologize. BTW, I also like to force trunk ports to trunk and turn off all negotiation. It prevents weird things from happening. :)
To the original poster, verify that there is a trunk (I agree with d-fillmore; force it to trunk) and check your VTP mode, domain, and password on the 3750.
10-27-2006 05:27 AM
FYI - I have another setup which is pretty much identical, and I have only setup trunking on one switch and left the other end without trunking. The only difference is both of the switches are C3550-48's. These two connections have always worked fine.
Switch 1
interface FastEthernet0/1
description Uplink port to ** port fa0/47
switchport trunk encapsulation dot1q
switchport mode trunk
Switch 2
interface FastEthernet0/47
description Uplink to *** port fa0/1
switchport access vlan 21
no ip address
duplex full
speed 100
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