topic Re: New VOIP system - VLAN Routing questions in Switching

New VOIP system - VLAN Routing questions

cyoungblut — Tue, 05 Mar 2019 23:56:26 GMT

Hello - I have a flat network (one subnet) that we are adding a VOIP system into. We are installing a 4510 Switch in the core and each of the 4 wiring closets will have one 3560-POE 48 port switch with fiber back to the core. I think I understand the use of a separate VLAN for the voice network but I'm having a hard time getting the setup of the separate subnet for the voice vlan and getting that subnet to talk to the other VLAN for configuration from the TFTP server (primary call manager). The 4510 has a primary and secondary supervisor engine. The Primary and secondary call managers are on the data subnet. Can someone point me in the right direction for getting the VLANs and Routing information correct? The ports on the switches will need to run multiple vlans since the computers on the network will hook into the new phones. The new IP phones are mostly 7941s with a few 7911s and 7970s.

Thanks

Re: New VOIP system - VLAN Routing questions

Amit Singh — Tue, 08 May 2007 14:08:57 GMT

Chris,

I am listing the steps that you need to do :

1. Create two separate vlan on the core switch 4510 and on all the 3560's. You can do it manually or use VTP for propogating vlans from the core to access switches.

2. Create trunk between core and all the 3560 switches.

3. Once the trunking is done, configure the 3560 switch ports to use both the Data and Voice vlan. Do this:

conf t

interface gig 0/1

switchport mode access

switchport access vlan 1 <-- Data Vlan

switchport voice vlan 2 <-- Voice vlan

4. Once the port config is done, configure SVI's on coare 4510 for both voice and data vlan

conf t

int vlan 1

ip address a.a.a.1. b.b.b.0

no shut

int vlan 2

ip address x.x.x.1 y.y.y.0

no shut

You might have to use " ip-helper address " command under the SVI interface if your DHCP server for ip phones is on a diff subnet.

HTH,

-amit singh

Re: New VOIP system - VLAN Routing questions

ankbhasi — Tue, 08 May 2007 14:11:15 GMT

Hi Friend,

First you need to create 2 vlans in your database. One you alreday have and second you can create.

Once 2 vlans are created you can verify the same using "sh vlan". After that configure your interfaces on which you will connect you ip phone as

switchport mode access

switchport access vlan

switchport voice vlan

Once you are done with this on your sup engine configure inter vlan routing

ip routing

interface vlan

ip address x.x.x.x x.x.x.x

interface vlan

ip address x.x.x.x x.x.x.x

Make sure the ip addresses which you configure on your vlan interfaces should be assigned as the gateway to respective devices in their vlan. Also make sure you configure trunk links between your 3560 switches and 4510 switch allowing only these 2 vlans.

HTH

Ankur

Re: New VOIP system - VLAN Routing questions

mohammedmahmoud — Tue, 08 May 2007 14:30:12 GMT

Hi,

In the addition of the spectacular explaination from Amit and Ankur, i'd recommend that you use Auxiliary/Voice VLANs:

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_guide_chapter09186a008077444f.html

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

Re: New VOIP system - VLAN Routing questions

cyoungblut — Tue, 08 May 2007 15:56:42 GMT

Ok, I have the two vlans created on my core 4510 switch. For now I am just working with that switch and will worry about the trunks to the IDFs later (if that is ok?).

I have data vlan 10 and voice vlan 23. I have my data subnet, ie. 10.0.0.0/24 and a voice subnet ie 10.0.23.0/24. I have DHCP enabled on my Cisco Call manager (ip. 10.0.0.176) to supply IP addresses (in the subnet 10.0.23.0) to the phones. Computers get their IP address from a DHCP server on subnet 10.0.0.0. I'm confused in which IP addresses to put on the VLAN interfaces? Sorry but I've not had to deal with VLANs and switch routing before so I apologize if this is somewhat elementary.

Thanks for all your help.

Re: New VOIP system - VLAN Routing questions

ankbhasi — Tue, 08 May 2007 16:03:41 GMT

Hi Friend,

As you mentioned you want vlan 10 for data in subnet 10.0.0.x/24 and vlan 23 for voice in subnet 10.0.23.x/24 you have to create 2 layer 3 interfaces on your sup engine.

Something like this

interface vlan 10

ip address 10.0.0.x 255.255.255.0

interface vlan 23

ip address 10.0.23.x 255.255.255.0

ip helper-address 10.0.0.176

HTH

Ankur

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Re: New VOIP system - VLAN Routing questions

mohammedmahmoud — Tue, 08 May 2007 16:04:05 GMT

Hi,

Interface vlan 10

ip address 10.0.0.1 255.255.255.0

no shut

Interface vlan 23

ip address 10.0.23.1 255.255.255.0

ip helper-address 10.0.0.176

no shut

And make sure that these IPs are the gateway of you computers and IP Phones respectively.

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

Re: New VOIP system - VLAN Routing questions

cyoungblut — Tue, 08 May 2007 17:50:08 GMT

Thank you much - I am learning I think!

Another questions because I'm having difficulty getting the phone to register with the call manager using dhcp. The primary call manager is in the same subnet/vlan as our data network - how does the phone (which is in a different vlan/subnet) know to use the call manager (tftp server) as its dhcp server instead of the dhcp server that our network pcs use. Again, many thanks! I am learning.

Re: New VOIP system - VLAN Routing questions

ankbhasi — Tue, 08 May 2007 18:00:45 GMT

Hi Friend,

When your IP Phones send a DHCP request on vlan 23 it will be a broadcast and will hits vlan 23 layer 3 interface on your sup engine where it will be converted to the unicast ecause of ip helper command.

Now the unicast request will be sent by vlan 23 as a source ip address and will reach the DHCP server where DHCP server will inspect the source ip address from where the request had come and when it matches the DHCP pool subnet which you might have created for voice vlan it will return the ip address form voice vlan subnet.

HTH

Ankur

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Re: New VOIP system - VLAN Routing questions

mohammedmahmoud — Tue, 08 May 2007 18:03:43 GMT

Hi,

The inter-VLAN routing that you've configured (interface VLAN10 and Interfac VLAN 23 - and make sure that "ip routing" is configured on the switch) will do the reachability job between the 2 VLANs.

On the Interface VLAN 23, put the IP address of the DHCP server that you want the IP Phones to use using the "ip helper-address" command. Further you can configure the DHCP to give the IP phones the tftp server ip address.

Please don't hesitate for any further questions.

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

Re: New VOIP system - VLAN Routing questions

cyoungblut — Tue, 08 May 2007 19:57:21 GMT

The DHCP server (in this case the primary call manager) can reside in a different subnet and vlan, correct...hence the ip helper-address command?

Also, how do I know if IP Routing is enabled on the 4510 switch. I type in IP Routing from the config line and it accepts the command but I don't see anything when I do show run.

Re: New VOIP system - VLAN Routing questions

Amit Singh — Wed, 09 May 2007 04:06:03 GMT

Yes, you are right.

IP routing is enabled by default on Cat4500 Sup engines.It should list under the " show run ". Please paste the output.

To check if it really is working, Type " show ip route " and you should see all the SVI's that you have configured on the box.

-amit singh

Re: New VOIP system - VLAN Routing questions

cyoungblut — Wed, 09 May 2007 12:48:36 GMT

Attached are results from my Show Run and Show IP Route (at the end).

I'm only using voice vlan 23 and the native vlan 1 for now.

Re: New VOIP system - VLAN Routing questions

ankbhasi — Wed, 09 May 2007 12:56:40 GMT

Hi Friend,

Yes IP routing is enabled on your switch and your config looks perfect. I believe your IP Phones should receive an ip address now from your DHCP server.

Can you confirm the same?

Regards,

Ankur

Re: New VOIP system - VLAN Routing questions

cyoungblut — Wed, 09 May 2007 15:00:30 GMT

If I leave the 7911 phone set for DHCP Enabled it wants to pull an IP address from our 10.0.0.0 subnet. It does show as being in Voice Lan 23. If I disable DHCP on that phone and set the IP Address to 10.0.23.11 (an ip in our voice subnet) I get a message "router not in subnet".

I'm thinking it is in the gateway configuration... I have our CM1 set up with IP 10.0.0.176 and have DHCP server running on that with a DHCP pool in the 10.0.23.0 subnet. Is this ok? I want the phones to get an IP from the 10.0.23.0 subnet. Our 10.0.0.0 subnet gateway is 10.0.0.254.

On VLAN 23 I have the IP helper address set to our TFTP Server (which is our CM1, 10.0.0.176). Am I missing the boat on something here? Our 4510 switch IP address is 10.0.0.175.

Re: New VOIP system - VLAN Routing questions

ankbhasi — Wed, 09 May 2007 15:09:48 GMT

Hi Friend,

Your config is fine. I believe you ip phone is connected on gig 5/2 correct? Your CM1 which is working as your DHCP server has an ip address 10.0.0.176 correct?

Also I believe whe you have configured DHCP pool for your voice subnet you also have confgured gateway to be returned as DHCP option in your DHCP server. Also want to make sure you are returning 10.0.23.1 as the gateway addres for your ip phones?

Regards,

Ankur

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Re: New VOIP system - VLAN Routing questions

cyoungblut — Wed, 09 May 2007 15:26:44 GMT

Yes - the ip phone is on gi5/2. CM1 is working as the DHCP server and has an ip address of 10.0.0.176.

Here is what I have configured under the DHCP Server setting in CM1...

Host Server... 10.0.0.176

Primary TFTP Server IP Address (Option 150) 10.0.0.176.

ARP Cache Timeout 300

IP Address Lease Time 36000

Renewal (T1)Time 36000

Rebinding (T2) Time 36000

Under DHCP Subnet I have the following..

DHCP Server: 10.0.0.176

Subnet IP Address: 10.0.23.0

Primary Start IP Address: 10.0.23.10

Primary End IP Address: 10.0.23.15

Subnet Mask 255.255.255.0

Primary TFTP Server (Option 150) 10.0.0.176

Arp Timout 300

IP Addr Lease Time 36000

Renewal (T1) 36000

Rebinding (T2) 36000

Re: New VOIP system - VLAN Routing questions

ankbhasi — Wed, 09 May 2007 15:31:29 GMT

Hi Friend,

In your DHCP server configuration I do not see its returning a gateway ip address for vlan 23 which is 10.0.23.1 , I believe its option number 3.

Also can you configure one another port on your switch for "switchport access vlan 23" and connect one computer to that interface and see if that computer gets an ip address from your voice vlan subnet.

Regards,

Ankur

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Re: New VOIP system - VLAN Routing questions

cyoungblut — Wed, 09 May 2007 15:41:55 GMT

Where do I set the gateway IP address for vlan 23 (10.0.23.1 - option 3??) I'm confused there.

Re: New VOIP system - VLAN Routing questions

ankbhasi — Wed, 09 May 2007 15:54:30 GMT

Hi Friend,

In your DHCP server you have configred option 150 to return TFTP server ip address so in same way also configure option 3 to returen router address.

I believe your CM1 is a cisco call manager which uses windows as its OS correct? then under your DHCP pool you will get an option to configure OPTIONS to be returned in DHCP packets and the way you have configured option 150 same way confoigure option 3 to return router address which will be 10.0.23.1 which you have configured on your layer 3 interface on switch.

HTH

Ankur

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