VLAN questions

[vontech615]

I am setting up a voice vlan for our company's IP Phone traffic.  Our network is pretty much as follows...

(From End to End)

PC connects to phone, Then to Adtran switch. 

The Adtran connects to a L2  Dell Switch and that connects to another Dell Switch. 

We have a Windows 2K3 server doing DNS, DHCP that connects off the Dell switch. 

We also have a NAS connected to the Dell.  Just 1 router.

PC--->Phone----->Adtran 1544---->Dell L2 Switch A---->Dell L2 Switch B----->Sonic Wall Router/Gateway

                                                            |                                       |

                                                    Windows 2K3 Server            NAS

For brevity I'll list what I know first then what my questions are.

What I Know:

-All devices on the network (DHCP, NAS, copier, pc, phones,etc.) are on the default VLAN 1 right now.

-For now I'm just going to seperate phones to different VLAN.  All else remains on VLAN 1.

-I can create a Voice Vlan

-The phone recognizes the Voice Vlan when powered on via LLDP

-The phone tries to get a DHCP Address

-The phone cannot because I haven't trunked any of the ports where Switch's connect to each other

-The Dell switches do Trunking

-I need to set up a differenet scope in the DHCP server for the phones

-The 1544 can do IP Routing

My questions:

-Does this switch support IP Helper address to point to the DHCP server?

-Windows server, NAS, Router connect to the switches.  Do the ports where they connect have to be set to trunk?

-What am I missing?

[jayh]

vontech615 wrote:

For brevity I'll list what I know first then what my questions are.

What I Know:

-All devices on the network (DHCP, NAS, copier, pc, phones,etc.) are on the default VLAN 1 right now.

-For now I'm just going to seperate phones to different VLAN.  All else remains on VLAN 1.

-I can create a Voice Vlan

-The phone recognizes the Voice Vlan when powered on via LLDP

-The phone tries to get a DHCP Address

-The phone cannot because I haven't trunked any of the ports where Switch's connect to each other

-The Dell switches do Trunking

-I need to set up a differenet scope in the DHCP server for the phones

-The 1544 can do IP Routing

My questions:

-Does this switch support IP Helper address to point to the DHCP server?

-Windows server, NAS, Router connect to the switches.  Do the ports where they connect have to be set to trunk?

-What am I missing?

What do the phones use as a SIP gateway?  Same Sonicwall or is there an IP PBX on-prmise?

• Yes, the switch supports IP helper, but it also supports DHCP server internal and I would use its internal DHCP server rather than two scopes. We've seen Windows DHCP servers misbehave when they have access to multiple VLANs.
• Windows server and NAS don't need or want to be trunked.  Router may or may not depending on your topology.  If the router is going to do NAT and SIP for voice VLAN, then you'll want to make it a trunk and put both VLANs on it.
• Ports interconnecting switches that have ports in both VLANs need to be trunks.
• You may want to do IP routing on the 1544 if the workstations need to communicate with the phones or PBX for screen pops, etc.

The missing piece of the puzzle is how you intend for the phones to reach the outside world.  What device on the Voice VLAN will be used for the phones to reach the rest of the telephone network?

[vontech615]

That's a great question because I meant to include that.  We have an SV8100 IP PBX.  It also sits on VLAN 1.

SV8100: IP-PBX | NEC

I would like to keep my Windows 2k3 server in the equation for now. So for arguments sake let's assume it's staying in the network.

So what I've done...

1. Created a seperate scope 10.10.10.X in the DHCP for the Phones.

2. I set up VLAN 10 as the voice vlan on all switches.  I gave it an IP address in the 10.10.10.x range. I added the vlan 10 on the Dell switches.  I guess they don't need IP Interface though?

3. Enabled IP Routing because we do have a softphone.

4. Set all the appropriate ports to trunk ports that connect between switches and allowed all VLANs on all trunks/all switches just in case they weren't.

5. I went to the VLAN 10 interface and ran command ip helper-address dhcp address

6. I issued commands ip forward-protocol udp domain & ip forward-protocol udp bootps

7. I also globally enabled IGMP snooping and Bridge Multicast filtering on the Dell's.  I'm not sure that it needs but read that in an article where someone was setting up an AVAYA system with Dell switches.

8.  I did set the port going to the DHCP server on one of the Dell's as a trunk but your saying I don't need to do that?

So, all that and still when I turn my phone off and on it just sits at "DHCP Connecting ..... (VLAN)"  for a while and then says it can't find the server.  I then just go back in and issue the no switchport voice vlan 10 on my interface and it's back to normal.

[jayh · Accepted solution]

OK, the IP PBX will want to be on the voice VLAN as an access port on VLAN 10 only. Renumber it to 10.10.10.[something]. 

I would strongly recommend against using a Windows server as a DHCP server in a multi-VLAN environment.  Best would probably be to have the IP PBX be the DHCP server for the phones.

When enabling IP routing, you'll need a VLAN interface on VLAN 1 with a static IP in the existing data vlan.  You'll also need a VLAN 10 interface on the switch with a static IP in the new 10.10.10.x subnet.  You'll also need a static route on the Sonicwall to the 10.10.10.x subnet with a gateway of the VLAN 1 interface on the switch. 

[vontech615]

Ok.  That makes sense to put the PBX on the same VLAN as phones and let it handle the Phones DHCP.  I already have an IP Address on VLAN 1 interface for the data and same with the VLAN 10 interface.

So, even though I have ip routing going enabled on the 1544, the Sonicwall still needs a static route to the 10.10.10.x vlan interface?

[jayh]

vontech615 wrote:

So, even though I have ip routing going enabled on the 1544, the Sonicwall still needs a static route to the 10.10.10.x vlan interface?

The Sonicwall is presumably the default gateway for devices on VLAN 1.  If it has no information regarding the 10.10.10.x subnet it will send traffic for 10.10.10.x out the Internet where it will be discarded. When your softphone on VLAN 1 wants to reach the PBX or a phone on VLAN 10, this will fail.

So, on the Sonicwall you'll want a static route to 10.10.10.x/24 with a gateway of the VLAN 1 interface of the switch.

[vontech615]

Ok that also makes sense. I'm still not sure why the phone itself couldn't reach the DHCP server. It seems liie my setup was correct. I'm out of the office now but will be back on Monday to test more. Thanks for your help so far. Have a good weekend. If you get one.

Sent from my Verizon Wireless 4G LTE smartphone

[vontech615]

Ok, so we got another Adtran switch.  The same 24 port 1544 switch that we have the phones/pc's running to.  We are going to get rid of our Dell switches.  For some reason trunking isn't working properly through the Dell switches from the Adtran and we had plans to upgrade them anyway.  This should make this easier to get setup.  We only have 25 phones should I just set them static so I can avoid the DHCP issue?

[jayh]

You could, but I'd just configure your IP PBX as the DHCP server for that VLAN.  Lots more scalable.

As I commented earlier, Windows DHCP servers don't perform well in multi-VLAN environments.  I would ensure that the port where your Windows DHCP server is connected is configured solely as an access port on the data VLAN, no voice VLAN.

[vontech615]

I really appreciate your help on this.