Avaya IPO DHCP Issue, ACK Error 1

[bbaits25]

We are having issues with our DHCP leases with our Avaya IPO 500 v2 with our 9608 phones (it's setup for Server). I receive a ACK errors when it tries to get a DHCP lease.

We have two VLANS

VLAN 1: Data
VLAN 10: Voice

We have a Dell Powerconnect 3548 which has the VLANS configured on the appropriate ports.

VLAN 1: e1 - e24
VLAN10: (untagged)e25 - (untagged)e48, Trunk Port: G4

If we put a static IP address on the phone it works, we have the Trunk port for G4 that goes into our Firewall (Sonicwall NSA2400). It runs into one phyical port that is setup for VLAN1 for our data network/subnet and a virtual port with the Voice network/subnet with the appropriate VLAN10 assigned to it.

If we plug in a computer into the phone subnet we receive an IP address on the phone system, with the phone we receive an ACK error. The Sonicwall acts as our DHCP Server for Data, so we have the Avaya IPO and Sonicwall dealing out DHCP addresses.

I was wondering if anyone one has had issues with 2 DHCP servers running on the same switch but separated by VLANS, The trunk port on G4 has access to both the Data and Voice.

 

[DavidCT]

Make the switch port that the ip office control unit is plugged into an access port only, set to untagged vlan10.

 

[intrigrant]

The LAN DHCP server MUST be on a switch port only configured for the data LAN, the VLAN must be blocked on this port.

 

[IPGuru]

Thanks intrigrant.

That should have been obvious but it explains why things suddenly stopped working @ one of our customers Doh


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Do things on the cheap & it will cost you dear

 

[bbaits25]

Ok so how would I access the Phone system network from the Data VLAN? Should I use the second LAN port on the phone system for management? Or do I need to do some DHCP relay on the Sonicwall to forward the phone's vlan 10 to the phone system?

 

[amriddle01]

No, just stick the second LAN port in the other VLAN as you thought

 

[Bas1234]

You could do on the router but that is made to do other tings, better is to setup DHCP relay or an IP Helper on the switch and give the phones and pc's the switch IP as the Gateway. But this is basic on networking.

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[bbaits25]

Unfortunately the dell power connect 3548 is not a layer 3 switch, its a layer 2 so no IP helper address or dhcp relay. I think this has to be done in the sonicwall for it work? The weird thing is we've had this deployed for over a year now and it started happening about 3-4 months ago. No changes on the network or additions.

 

[intrigrant]

If each VLAN ( data and voice ) have its own DHCP server then each DHCP server MUST be invisible for the other, otherwise you get the ACK errors and DHCP whoes.

Best way to do it:
Data DHCP on a LAN port programmed only for DATA VLAN, forbid the Voice VLAN, IP Office LAN1 port also on a port only for Data VLAN.
Voice DHCP server ( IP Office LAN2? ) on a port only for Voice VLAN, forbid data VLAN.
DO NOT USE IP Helper, turn it off if it is on, if the switch is capable of VLAN Routing : TURN IT OFF, it is seldom needed and a real router does a far better job.
Then program a site specific option 176 and/or 242 wich only have the VLAN parameter telling the Avaya phones to boot in the Voice VLAN.

Works 100% all the time without any failure.

 

[bbaits25]

If we have multiple branch locations that have VPN connections that make internal branch to branch calls, wouldn't this stop working due to segmenting it off and not allowing the Data and Voice to communicate?

 

[amriddle01]

Not if you reconfigure things to account for the change

 

[bbaits25]

hmmmm, the rest of the branch's are on a Flat LAN (VLAN1 default), different subnets but is separated by physical port (data is X0 and Phone in X1). The DHCP leases that the branch's are getting are locally from there Avaya IPO. So i guess im confused on how the branch locations will access from there phone subnet to our phone subnet if they don't have access to the VLAN10 when we get rid of the Trunk port to allow both vlans, they would only have access to LAN1 (Data subnet).

 

[amriddle01]

So do as advised and add the second LAN port of the system to the Data VLAN and route traffic from the system destined for those branches out that LAN port, it's just an IP route change on the system once the LAN port is connected

 

[bbaits25]

So the LAN2 on the Avaya IPO, I would add an IP Route and add the Data VLAN1 gateway?

 

[amriddle01]

Yes, so if the LAN2 is 192.168.10.250 in the data VLAN and the gateway is 192.168.10.1 add the route:

0.0.0.0
0.0.0.0
192.168.10.1
LAN2

Done

 

[amriddle01]

Assuming you don't need to route traffic for other subnets/networks out LAN1 of course

 

[bbaits25]

OK got that.

I will have two routes.

IP Route 1: VLAN10 subnet

0.0.0.0
0.0.0.0
172.25.87.101
LAN1

IP Route 2: VLAN 1 subnet

0.0.0.0
0.0.0.0
172.18.87.101
LAN2


I guess my confusion is that if I want to access the phone system, I will have to go through the Data VLAN1.

 

[amriddle01]

No, you don't need a route for the phone vlan, just the one I mentioned (for routing all traffic for all non local addresses out the data VLAN)

 

[bbaits25]

Ok there is a default route right now in the phone system.

IP Route 1:

0.0.0.0
0.0.0.0
172.25.87.101
LAN1

 

[amriddle01]

That's not default, that's there from when you routed all traffic out that port (was added by somebody). Now you need to remove that and add one for the Data VLAN as I mentioned (but with relevant addresses for your network)