DHCP Issue

[pakman]

I have the following situation.

I have a site with two HP switches with a voice vlan and data vlan there are IP helper statements on the voice vlan pointing to the PBX . The PC's get there DHCP info from a branch server while the phones get there's from the PBX. Not sure when it started but noticed under leases on the branch server there was 3-4 phones getting an IP address from the sever vs the PBX. Two of these phones reside off one switch and two off the other and on both switches the port they live off of are tagged properly to the voice vlan and untagged in the data vlan. I cannot explain how these phones are getting to the branch server for their IP info. I don't hardcode phones so I know that's not it.

The following our my DHCP options on the PBX
ID=3 Name=Router value=10.x.x.x
ID=6 name =DNS Sever vlaue=10.x.x.x,10.x.x.x. note the first value for the DNS server is our branch server
ID=15 name=domain name
ID=44 Name=NetBIOS name server
ID=125 Name =MITEL value= id:ipphone.mitel.com;sw_tftp=10.x.x.x;call_srv=10.x.x.x;dscp=46
ID=128 name TFTP server
ID=129 name Call Server
ID=130 name IP phone identifier
ID=134 name DSCP value=46

Is there any documentation out there explaining how DHCP works within the phones? Ex. when a phone first boots up does it send some kind of identifier withing the packet identifying itself as a phone?

Thanks,

[lundah]

when a phone first boots up does it send some kind of identifier withing the packet identifying itself as a phone?

Yep, this can be done via a couple of methods. With HP switches, probably LLDP. Check the config on those switches (and compare to one that doesn't have this problem if possible) and see if there's an issue with that setup.

[DB32120]

since your using HP switches I would go down the route of LLDP as Lundah said.

Take a look at the below as an example of LLDP on HP switches

Our basic HP config is as follows ( simple and seems to work well)


int 24
name "mitel"
Vlan 1
name "data"
ip address 10.100.10.10 255.255.255.0
untagged 1-23,25-28
exit
vlan 2
name "voice"
ip address 172.16.1.254 255.255.255.0
untagged 24
tagged 1-23,25-28
qos priority 5
voice
exit
ip routing
ip route 0.0.0.0 0.0.0.0 10.100.10.1
lldp run
- The mitel we have as 172.16.1.2 , 255.255.255.0 gateway 172.16.1.254 ( hp switch)
- in its DHCP server we dont provide any vlan options

The phone boots up and does a dhcp request
the switch recognises it as a voice device and forces it into vlan 2 where it does another dhcp request
the mitel's port is forced into Vlan 2 and every packet leaving it is tagged as vlan 2
- the mitel supplies the dhcp for phones
- our server  in the 10.100.10 network supplies any laptops / pc's with DHCP
our gateway 10.100.10.1 has a static route to the 172.16.1.0 network as follows

route 172.16.1.0 255.255.255.0 10.100.10.10

- ie route all 172.16.1.0 packets to the HP switch

The most important command is the "untagged in vlan2 for the Mitel port"

[johnp]

I think either the thb or engineering guide has lldp programming instructions for lldp on HP