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VLANs not propagating automatically on a cisco 3750 switch

MANGO247
MANGO247 asked
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I have recently joined 2 Cisco 3750 switches (Say A & B). Both are in same VTP Domain and in Client Mode. Trunking is working fine. Switch A is connected to Core switch through Fibre and Switch B is connected to Switch A through Copper. Both have default gateway pointing to Core switch. When i do Show VLAN i dont see any VLANs from on Switch B.

Spanning tree mode is rapid-pvst

sh vtp status is attached herewith on both

 vtpstatus.txt
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Author

Commented:
Do we need to add all VLANs manually or should they automatically be available on Edge switch
Don JohnstonInstructor
Top Expert 2015

Commented:
Looks the same to me.

Both switches have a configuration revision number of 79 and both have the same number of VLANs (26).

If  switch B was already at revision 79, then it wouldn't accept any updates with the same revision number.

If that's the case, change the VTP mode to transparent (on switch B) and then change it back to client. That will reset the revision number to 0 and it will then accept the updates from A.

Author

Commented:
Sorry below is SH VTP Status for Switch-B
VTP Version capable             : 1 to 3
VTP version running             : 2
VTP Domain Name                 : NMSI_MAIN
VTP Pruning Mode                : Disabled
VTP Traps Generation            : Disabled
Device ID                       : 3037.a604.4880
Configuration last modified by 10.100.100.57 at 3-2-93 01:32:42

Feature VLAN:
--------------
VTP Operating Mode                : Client
Maximum VLANs supported locally   : 1005
Number of existing VLANs          : 5
Configuration Revision            : 0
MD5 digest                        : 0x27 0x82 0x5B 0xC7 0x93 0xF0 0xBB 0x4F
                                    0xA9 0x39 0x4A 0x01 0x05 0xFE 0xFE 0xC7
Don JohnstonInstructor
Top Expert 2015

Commented:
Garbage in... Garbage out. ;-)

Check that the VTP domain name doesn't have a space at the end.

Also confirm the password (if used) is the same.

Finally, verify that a trunk exists between the two switches (show int trunk).


Author

Commented:
Thanks-

There is no space at the end
We have not used any password
Trunk exists and have limited number of VLANs allowed

I have not attached any device to Switch-B. Would that initiate vlan propagation?
Don JohnstonInstructor
Top Expert 2015

Commented:
>I have not attached any device to Switch-B. Would that initiate vlan propagation?

No

Please post the configs of Switch A and B and the output of a "show int trunk" and "show vtp status".

Commented:
You can also check the following:

Verify VLAN 1 is active on Switch B and is allowed and active on the trunk links
Re-apply VTP domain names
Bounce the trunk interfaces, "shutdown" then "no shutdown"
perhaps a little basic, but I see you have the trunks between the two 3750's but are the trunks in place running back to the VTP Server switch?  

Don JohnstonInstructor
Top Expert 2015

Commented:
>but are the trunks in place running back to the VTP Server switch?  


While that's important, it wouldn't keep an update from going between switch A and B.

Author

Commented:
>Verify VLAN 1 is active on Switch B and is allowed and active on the trunk links
Yes, VLAN1 is allowed and active

>Re-apply VTP domain names
I have re-applied domain name in Switch B

>Bounce the trunk interfaces, "shutdown" then "no shutdown"
Did shut/no shut on my trunk linke

Default gateway is same (i.e. Core) on Switch A & B. I can remotely telnet to both switches and able to ping all Interfaces on Core switch from both. The only problem is that i dont see VLANs on SwitchB



>but are the trunks in place running back to the VTP Server switch?  

No, trunks on Switch B only go back to Switch A through Copper and then Switch A is connected to Core through Fibre



Author

Commented:
Both Switch A & B are in client mode.
Don JohnstonInstructor
Top Expert 2015

Commented:
Once again...

Please post the configs of Switch A and B and the output of a  "show int trunk" and "show vtp status".

Commented:
Try switching to vtp transparent mode and then back to client mode?

If that doesnt do it, I'd be almost certain that the trunk or vlan1 could be culprit here.

Author

Commented:
Please find attached Show Run, Show int trunk, Show VTP stat
SwitchA.TXT
SwitchB.TXT
Don JohnstonInstructor
Top Expert 2015

Commented:
And what ports are being used to connect these two switches?

Author

Commented:
>And what ports are being used to connect these two switches?

Ports used on SwitchA are Gi1/0/51 and Gi4/0/1

Ports used on SwitchB are Gi1/0/1 and Gi1/0/2

Connectors are Copper.



Don JohnstonInstructor
Top Expert 2015

Commented:
Well this is puzzling.

Both links are up and running (STP has one blocked but that's expected).  VLAN 1 is functional between the two switches as indicated by the show int trunk output and the fact that you can telnet to both switches.

Looks like you've changed the domain name but they appear to be the same.

Interesting...


Don JohnstonInstructor
Top Expert 2015

Commented:
I think I see it.

On the two switches, issue the command "show vtp password".

I think you'll see that either the passwords are different or one switch is configured with a password and the other isn't.

Author

Commented:
We dont have any password for vtp
Instructor
Top Expert 2015
Commented:
Did you run the command "show vtp password" on both switches? Please post the output.

From your switches:

Switch A:
MD5 digest                        : 0xB6 0x23 0x84 0x87 0xDD 0xC7 0x0F 0x4C 0xDB 0xEF 0x85 0x92 0xCF 0xEE 0x6B 0x8F
Switch B:
MD5 digest                        : 0x27 0x82 0x5B 0xC7 0x93 0xF0 0xBB 0x4F 0xA9 0x39 0x4A 0x01 0x05 0xFE 0xFE 0xC7

When I tested this on a pair of switches, these values were the same when the two switches had the same password or no password. But if one switch had a password and the other didn't, the MD5 digest was different.

Commented:
Try delete VLAN.dat

Set to transparent and back to client

Author

Commented:
Great... Thanks DonJohnston. You were right. It was vtp password. Its all working now
Don JohnstonInstructor
Top Expert 2015

Commented:
"We dont have any password for vtp "

If nothing else, the most valuable lesson here (IMHO) is when asked about a setting, NEVER ASSUME.you know what it is set to. ALWAYS check.

:-)