vlan trunk problem

[stoofer]

Hi guys,

We have a dhcp server running in our network for vlan310, we are getting ip leases when we connect a pc to a port on our first switch (C4507). There is a trunk port configured to a second switch (3750). Now when we connect a pc to a port (gig3/0/36) configured for the vlan310 on the 3750 switch we do not get an ip lease from our dhcp server.

As far as I can see the trunk ports and switch port are configured correctly, any thoughts are appreciated .

here are some config snippets from our C4507 switch :

!
interface TenGigabitEthernet1/5
description ++ Uplink - 3750 Te3/1/1 ++
switchport mode trunk
switchport nonegotiate
ip arp inspection trust
logging event link-status
udld port aggressive
ip dhcp snooping trust
!

sh vlan

310 Guest active Gi5/1, Te6/9

and on our second switch 3750

!
interface TenGigabitEthernet3/1/1
description ++ Uplink - C4507 Te1/4 ++
switchport trunk encapsulation dot1q
switchport mode trunk
switchport nonegotiate
ip arp inspection trust
srr-queue bandwidth share 1 25 20 15
priority-queue out
mls qos trust dscp
ip dhcp snooping trust
!

!
interface GigabitEthernet3/0/36
description *** Guest ***
switchport access vlan 310
switchport mode access
switchport nonegotiate
switchport port-security maximum 4
switchport port-security aging time 1
switchport port-security aging type inactivity
switchport port-security aging static
switchport port-security
no logging event link-status
srr-queue bandwidth share 1 25 20 15
priority-queue out
no snmp trap link-status
storm-control broadcast level 40.00 20.00
storm-control action shutdown
storm-control action trap
spanning-tree portfast
spanning-tree bpduguard enable
spanning-tree guard root
!

310 Guest active Gi2/0/29, Gi2/0/45, Gi3/0/5, Gi3/0/12, Gi3/0/36

[balaji.bandi]

On the switch where Pc connected, did you created VLAN 310 ?

post

show vlan

show spann brief

[stoofer]

yes the vlan is created on the switch where the pc is connected

sh vlan

310 Guest active Gi2/0/29, Gi2/0/45, Gi3/0/5, Gi3/0/12, Gi3/0/36

[stoofer]

bump this thread, still having issues.

thanks for any input

[balaji.bandi]

Is this switch as Stack?  Is the port coming up when the Pc connected ? when PC connected

post below output :

show interface GigabitEthernet3/0/36

show interface status | in connected

ok If PC configured one of the spare IP as static in VLAN 310, are you able to ping VLAN 310 Layer 3 IP address?

I would start with basic config on the switch port first before i tighten the security :

example :

default interface GigabitEthernet3/0/36

interface GigabitEthernet3/0/36

switchport access vlan 310
switchport mode access

[stoofer · Accepted solution]

hello guys,we figured it out, it was a spanning-tree event that occurred and the affected vlan path was pointing to a backup dhcp server which was not active.

thanks for the input

[balaji.bandi]

glad you were able to resolve the issue, i am under the impression of the same spanning tree issue.

thank you for the feedback.