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New Member

adding support for IP Telephony to network

We are in the process of getting a new phone system. The new system is capable of supporting Voice over IP and the "phone" guys are saying they are going to test and move to IP phones. They have also talked of creating IP Trunks between various remote locations for phone service and/or voice mail support. Other than the phone systems we are a complete Cisco shop.

My network consists of the following...

4506 as my core with 3560s in each floor IDF as distribution

2950s are connected to the 3560s to serve as access

3750 stack supporting my server farm

I run several VLANs and have been trying to figure out to fit the new PBX and VoIP into the infrastructure. I run the following VLANs ..

One VLAN for each floor (VLAN2, VLAN3, VLAN10)

One VLAN for the server farm (VLAN4)

One VLAN for network device management (VLAN5)

One VLAN for the IS department (VLAN6)

One VLAN for our wireless network (VLAN7)

I do not use VLAN 1 for anything

I have been reading through topics and docs on-line looking for what needs to be changed network wise to support this. I know that I will need to create additional VLANs to support the voice traffic and will create one for each floor. It appears that I need to create trunks between the access switch and IP phone and including the data VLAN as well as a voice VLAN. The is where the questions start.

1) What is the difference in the access VLAN and a voice VLAN? The samples I have seen use these instead of a restricted vlan to flow on the trunk.

2) The devices in the PBX that need to be part of the "voice VLANs", do I define them as access VLANs or voice VLANs? This would include the "IPSI", "C-LAN" and "MEDPRO" cards in the PBX. Since this handles signaling and is needed by the VoIP calls I am figuring they will be in one of te voice VLANs.

3) Do I need to do anything from a QOS standoint to keep things flowing smoothly through the switches?

4) I have no clue about what is needed to support IP Trunking across my WAN.

7 REPLIES
Silver

Re: adding support for IP Telephony to network

New Member

Re: adding support for IP Telephony to network

Thanks for the links .. This is givin me a good start.

Hall of Fame Super Silver

Re: adding support for IP Telephony to network

1) There is really no difference, the reason for seperate ones is so you can seperate the 2 networks for security, and QoS reasons, this way you can easily block data network traversing into voice network and prioritize voice packets, as well as establish trust boundries.

2) You can define them either in voice VLANs or as I prefer seperate voice server VLAN.

3) Yes, QoS is very important, refer to the QoS SRND found at cisco.com/go/srnd

4) Hmm, trunking accross WAN? Depending on your WAN technology you will need to provision QoS toolsets such as LLQ, Shaping, Policing, Compression, LFI, also refer to the SRND doc.

Please rate all helpful posts!

Chris

New Member

Re: adding support for IP Telephony to network

Thanks for the answers to my questions. Why is it that the more one reads the more questions there are?

I think creating the voice server vlan is a good idea as I will have several "voice" VLANS. We are a multi-floor location and there will be a "voice" vlan for each floor.

We are using an Avaya PBX and Avaya IP phones so I have started looking through their IP telephany Implementation Guide. The items there are similar to what I am pulling of CCO in regards to the basic infrastructure.

One thing they do mention is that I need a TFTP server and this information is passed to the phone via DHCP and option 176. DHCP is served up from the 4506 core switch. Do you know if the CISCO DHCP server supports this? I am going to go through the IOS DHCP configuration guide to see what it says.

Now I just have to stay one step ahead of the phone guys wanting to implement a few test phones before I can get everything that I feel needs to be in place.

Bronze

Re: adding support for IP Telephony to network

Brent, i have thousands of avaya ip phones on my cisco network, with no issues. a couple pointers.

1) Aux/voice vlans work with avaya phones so u don't have to use setup explicit dot1q trunks.

2) avaya phones now can use HTTP or HTTPS instead of an TFTP server for firmware image updates...i use IIS and apache in my enviorment for this. or you can use the avaya server perform this task, since it runs redhat enterprise linux.

3)yes dhcp on a router works fine with option 176 setup as ascii example:

ip dhcp pool local-dhcp-pool

import all

network 172.29.28.16 255.255.255.248

default-router 172.29.28.17

dns-server x.x.x.x x.x.x.x

domain-name xxx.com

netbios-name-server x.x.x.x

netbios-node-type h-node

option 176 ascii "MCIPADD=172.24.99.200,MCPORT=1719,HTTPSRVR=172.24.98.250"

4) you might want to look at planning for "Network Regions".. in essece it the the logical group or mapping of ip address on the avaya system. Here'a a good document so you catch my drift:http://www.avaya.com/master-usa/en-us/resource/assets/applicationnotes/netw-region-tutorial.pdf

5) all avaya ip endpoints can perform both layer2 (cos) and layer 3 qos tagging(diffserv).(and the phone can re-write l2q cos tags if required) this configuration is done on the avaya media server and is sent down to all ip devices once registered.Also ensure the data switch ports with avaya ip phones and gateways(clan/medpro modules) have qos trusting enabled...example :

mls qos trust dscp (or)

mls qos trust cos

hope this helps!

New Member

Re: adding support for IP Telephony to network

kleo,

Here are the two DHCP scopes I have. The first is for the access VLAN and the second is for the voice VLAN. The option 176 are the same except for the L2QVLAN is NOT in the DHCP setup for the voice VLAN. This is per the IP Office documentation. My 5610SW phone is just not making it when it comes to using DHCP. I can hard code things and it seems to work just fine. Is there anything on the phones we need to make it work? I ran across a bullet about setting L2Q to a 2 which should turn off 802.1Q framing??

One step forward at a time ....

ip dhcp pool 3

network 172.20.3.0 255.255.255.0

dns-server xxx.xxx.xxx.xxx

domain-name xxx.xxx.corp

netbios-node-type h-node

default-router 172.20.3.1

option 176 ascii "MCIPADD=172.20.4.13,MCPORT=1719,TFTPSRVR=172.16.6.68,L2QVLAN=11"

lease 24

ip dhcp pool 11

network 172.20.11.0 255.255.255.0

dns-server xxx.xxx.xxx.xxx

domain-name xxx.xxx.corp

netbios-node-type h-node

default-router 172.20.11.1

option 176 ascii "MCIPADD=172.20.4.13,MCPORT=1719,TFTPSRVR=172.16.6.68"

lease 24

Brent

New Member

Re: adding support for IP Telephony to network

Don't understand it but everything seems to be workig this morning. Powered up a new phone and it went through the connection process without issue. Pulled an IP address from Access VLAN, switched to Voice Vlan, updated the software on the phone and then asked to be configured for an extension. We think the folks configuring the phone system did something ...

One question though .. How do you handle those few that currently have a hub in the cube to support more than one connection. I know the best solution would be to run extra drops but in the mean time what are the options? Can I connect the hub to the phone and then reconnect the PC and Printer to the hub?

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