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DHCP Clients not getting leases with Cisco VLAN

Posted on 2014-03-31
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Last Modified: 2014-04-10
I am absolutely stumped on this one.  I have a 3650 core switch with a whole heap of 2960s switches either directly connected or daisy chained one deep from the core.

We are transitioning there network into VLAN's and we created a VLAN for there phones to move into by Creating VLAN 3.  VTP Status is showing the results across all switches make a change on core clients get the updates.

However we have a Microsoft Hype-V server with a NIC dedicated to VLAN 3 running DHCP to offer the phones a ip address.   Problem is that some of the phones get a lease on VLAN 3 and these are usually on the directly connected switches, but the Phones on the outer switches do not.

I ran test on the default VLAN to see if a computer would pick up a lease on the out edge switches and it does, but if you plug the phone in it does not.  Bring the phone to the core or directly connected switches and it picks up a lease straight away.

Can anyone assist I have racked my brains trying to solve this one.
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Question by:ITSystemSol
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Expert Comment

by:Hassan Besher
ID: 39968409
make sure that phone connect to switch ports that have sw voice-vlan 3 and your cdp is on
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Author Comment

by:ITSystemSol
ID: 39968413
This vlan has just been setup as a basic VLAN with a DHCP server in it.  The Phones get a lease from DHCP with directly connected switches but anthying any further away and it does not work.
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Expert Comment

by:Hassan Besher
ID: 39968420
i need to see a config for sw config that is working when you connect the phone and the other sw config which doesn't work in getting ip when you connect your phone.
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Author Comment

by:ITSystemSol
ID: 39968485
Will upload asap
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Author Comment

by:ITSystemSol
ID: 39968535
So I have uploaded the core switch plus the switch connected to it with workin phones and then the last config of switch with non working phones.

CDP Information on 3 Switches
CoreSwitch Port Gi1/1 --> Port Gi1/0/49 PhonesWorkingSwithc
PhonesWorking Gi1/0/51 -- Port Gi1/0/25 PhonesNotWorking
CoreSwitch.txt
PhonesNotWorking.txt
PhonesWorking.txt
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by:Hassan Besher
ID: 39968561
DHCP server connected to which switch??
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Expert Comment

by:Hassan Besher
ID: 39968588
1) ensure that the switch port connected to DHCP Server is in trunk mode or in vlan 3
2) for testing puposes for now disable dhcp-snooping and arp inspection
3) ensure that ports connected to phones:
interface -----
 switchport access vlan 1
 switchport mode access
switchport voice vlan 3
spanning-tree portfast
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Author Comment

by:ITSystemSol
ID: 39968601
DHCP is connected to the Core Switch

The DHCP servers switch port is in VLan 3 as I said it is a Hyper-V host with several servers on it the DHCP interface is dedicated to VLAN 3

is disable DHCP snooping and arp inspection just on core or all switches

Will try the new config on ports.
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Expert Comment

by:Hassan Besher
ID: 39968621
so configure the port that is connected to Hyper-v as trunk encap dot1q and disable DHCP snooping and arp inspection for all switches from phones to dhcp server just for Testing purposes and try the new config on ports.
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Accepted Solution

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ITSystemSol earned 0 total points
ID: 39980024
Problem ended up being Spanning-tree root guard on the trunk ports.  When I ran the sh int trunk you could see trunks not carrying the VLAN information.  In the end I changed this option and it started working.
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Author Closing Comment

by:ITSystemSol
ID: 39991101
The issue was spanning tree root guard and once I ran no spanning tree it worked.
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