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VOIP Routing question

Scott.D
Occasional Advisor

VOIP Routing question

We are about to implement a Shoretel VOIP system and I am trying to get everything ready to go.

We are a school district with 8 buildings connected by a fiber optic network provided to us by another party. Each of the 8 sites has a separate Data VLAN and VOIP VLAN. The VOIP VLANs have been setp like below:

ProCurve Switch 3500(vlan-1)# vlan 102
ProCurve Switch 3500(vlan-102)# voice
ProCurve Switch 3500(vlan-102)# name DAC-VOIP
ProCurve Switch 3500(vlan-102)# ip address 192.168.122.1 255.255.255.0
ProCurve Switch 3500(vlan-102)# qos priority 7
ProCurve Switch 3500(vlan-102)# ip helper-address 192.168.120.12
ProCurve Switch 3500(vlan-102)# untag 20
ProCurve Switch 3500(vlan-102)# tag 1-19
ProCurve Switch 3500(vlan-102)# ex

By tagging the VLAN “Voice”, does the eliminate the need to deal with DSCP? I am still trying to grasp the need for DSCP and whether it is just a manual method of fine tuning.

My question is each building goes out the 3500 Switch onto a separate routed fiber VLAN. The VLAN is common to all 8 buildings. In this cast the 192.168.101.0/24 network. It is VLAN 100 and used for data.

What do I need to do to get the VOIP traffic to traverse the common fiber network? Does it just cross the same data network and keep the VOIP prioritization, do I tag it in some other way, or do I create another common VLAN on the fiber network that is tagged for Voice? If I do the latter, I would be creating a loop in the network unless I use lots of policies and/or static routes.

Finally – they VOIP company wants bandwidth set aside for the VOIP VLANs. It appears the bandwidth command is port related, not VLAN related. Is there a way to allocate 5Mbps on the common fiber network so data does not interfere with voice?

Thank you for whatever help you can provide. I know the answer is in the documentation but translating them into something I am grasping has been slow.

Scott
6 REPLIES
Mohieddin Kharnoub
Honored Contributor

Re: VOIP Routing question

Hi

DSCP is not dependent on VLAN-tagged ports to carry priority policy to downstream devices.

What you have done is enough to carry the Priority of the VoIP Vlan to the network, and with the use of 802.1p.

For the bandwidth management, i'm not sure why they asked you to preserve 5M for this Vlan, and you are using the 3500 series switches.

I can assure you that this switch can handle more than they expect, and from my field experience, the VoIP is very tiny comparing with the switch capacity and performance.

Good Luck !!!
Science for Everyone
Scott.D
Occasional Advisor

Re: VOIP Routing question

Mohieddin -

Thank you for the response. Any chance you could clarify on the routing question between sites as well?

----

My question is each building goes out the 3500 Switch onto a separate routed fiber VLAN. The VLAN is common to all 8 buildings. In this cast the 192.168.101.0/24 network. It is VLAN 100 and used for data.

What do I need to do to get the VOIP traffic to traverse the common fiber network? Does it just cross the same data network and keep the VOIP prioritization, do I tag it in some other way, or do I create another common VLAN on the fiber network that is tagged for Voice? If I do the latter, I would be creating a loop in the network unless I use lots of policies and/or static routes.

Thanks again,

Scott
Mohieddin Kharnoub
Honored Contributor

Re: VOIP Routing question

Hi

Its the Same Vlan, so routing is not involved here, and has nothing to do with the Vlan tagging.

Fiber is a media just like Ethernet, Tagging is the only way to make the Vlan cross from one switch to another, from one building to another .....

Since you used the QoS to make a higher priority to the VoIP Vlan, and you Tagged the Uplinks connected with the Fiber, THATS IT, you don't have to do anything else in your scenario, and your VoIP traffic will smoothly reach to all the places with the QoS you've defined.

Hope that cleared the point.

Good Luck !!!
Science for Everyone
Scott.D
Occasional Advisor

Re: VOIP Routing question

Mohieddin -

Thanks again for the quick answer.

Not sure if I am missing the answer or if I am not explaining well enough. I have 8 buildings, each with it's own Data and Voice VLANS.

They all go out onto a routed Fiber network that is a router VLAN for data. If I simpply, they will be crossing a ninth VLAN on fiber The VLAN on the fiber currently is data.

Example -

Building 1 -
Data - VLAN 110 - 192.168.110.0/24
Voice - VLAN 112 - 192.168.112.0/24

External Port on Fiber network - Routed
Data - VLAN 100 - 192.168.100.1/24
----------------------------
Building 2
Data - VLAN 120 - 192.168.120.0/24
Voice - VLAN 122 - 192.168.122.0/24

External Port on Fiber network - Routed
Data - VLAN 100 - 192.168.100.2/24
----------------------------
Building 3
Data - VLAN 130 - 192.168.130.0/24
Voice - VLAN 132 - 192.168.132.0/24

External Port on Fiber network -
Data - VLAN 100 - 192.168.100.3/24
----------------------------

Once the data leaves my internal building and jumps on the Fiber WAN, would I simply route it accross the Data VLAN and would it keep the 802.1p tag? Do I need to create a separate Voice VLAN on the Fiber so it can be tagged and routed?

Getting the data and voice routed is not an issue, I am just concerned with the Voice and Data not conflicting over the WAN stretch.

Sorry if I keep asking the same question different ways....

Thanks,

Scott
Mohieddin Kharnoub
Honored Contributor

Re: VOIP Routing question

Hi Scott

What you've done is more than enough.

- Add the QoS with high priority to the Voice Vlans in your Network.
- configure ports as VLAN-tagged members on the links between switches and routers in your network.

Then the QoS will be applied to the Voice traffic across you network, without the need to add any more Vlans.

Good Luck !!!
Science for Everyone
Jarret Workman
Frequent Advisor

Re: VOIP Routing question

Hi Scott,

The QoS priority of 7 should give priority to the Voice traffic as long as it is on a tagged port in a layer 2 switched environment. If the traffic hits an untagged vlan or a router layer 3 interface, then you might want to look at DSCP.

If the phones are capable of being configured, you may be able to configure the DSCP value on the phones, then configure the switch to look for the DSCP value and assign a QoS value to the traffic via the DSCP map.