VOIP/VLANs

[DammitKid]

Hi everyone,

 

I've not touched networking in a few years and I'm a bit rusty. I'm migrating to Teams as our phone system and have created a new VLAN from VOIP. What's the best way to configure the core and edge switches to get them working?

 

So far I've created the DHCP scope on our server, created the VLAN, assigned an IP address to the interface and created IP helpers for the DHCP server. I still need to tag the VLAN on the trunks and then assign switch ports and add the VLAN as a VOIP VLAN. Is there anything else I need to do to make sure it works? I'm thinking potentially needing a static route out to the firewall/internet? Or perhaps someone has a little crib sheet I can follow?

 

Again, quite rusty so any help is great.

 

Cheers

[psydii]

I'm unclear quite what the benefit is in trying to separate Teams voice traffic into its own vlan. Most devices running teams are likely to be PCs and therefore on whatever vlan they exist on?

 

You can apply QoS tagging to Teams traffic: https://docs.microsoft.com/en-us/microsoftteams/qos-in-teams

 

And then set up your switches and wifi to honour the appropriate prioritisation of this tagging. I think most modern wifi will automatically do best effort to honor DSCP tags these days.

 

What we did was to separate staff devices from student devices at the the VLAN+subnet level* then at the network edge have the separate subnets route/NAT in/out of their own dedicated IP address. Our ISP does not officially honor DSCP so at that point traffic is at the mercy of the ISP's policies.

 

*because this is actually a good idea generally. See also recent threads on improving security.

[DammitKid]

Most of our users aren't ready to adopt Teams as a phone system through a PC (crazy I know). So we have physical handsets that will remain in use for a few years before we gradually phase them out. I also what to separate out for dedicated VOIP traffic so that we can rectify other networking issues and isolating per device type enables us to do that.

 

I'll check the link. Thanks for replying

 

Cheers

[psydii]

Not played with Teams handsets yet (but will do as I can see the benefit of dedicated desk phone)

 

 

However on our legacy VOIP handsets the support LLDP-MED, so all internal edge switch ports are tagged with the voice vlan so if a phone gets plugged in it automatically uses the phone vlan, and if a non phone is plugged in that uses whatever the untagged vlan is (typically printer or staff-data, but occasionally cashless-catering).

[slugshead]

So we migrated to a hosted voice system 3 or 4 years ago and did exactly what you're doing.

 

With the amount of office moves and techs being rushed off their feet, half of the phones are not on the VOIP VLAN anymore ¬_¬

[RobD]

Depending on the switch, the terminology may change but I think this covers it:

 

On the Edge:

• Create vlan 50
  
• If its a dedicated port for a phone then you can untag the port, if its port for a phone that a PC also uses then you can tag the port with vlan and specify the vlan on the phone.
  
• tag vlan 50 on the uplink trunk to the core,
  

 

 

On the Core:

• Create vlan with a interface IP
  
• tag vlan 50 on the downlink trunk to the edge.
  
• Add a IP helper to point at the DHCP server,
  
• As for a route, depends whats already setup, if you're using a totally different IP scheme for DHCP then potentially
  

 

 

DHCP

Setup DHCP and use the vlan 50 IP as the gateway.

[Davit2005]

If you have a HP/Aruba/Cisco or a switch that supports it also set the vlan used as a voice vlan on the edge switch where the phone is plugged in. It only needs to be on the edge port and not the core.

 

The benefit of having physical VOIP handsets on different vlans is that it will limit interference and noise from network devices such as printers which can be detrimental to the quality of calls (I've experienced this with printers to the point where VOIP phones have been close to unusable)

[uccert]

For all VoIP/UC&C deployments I would recommend a dedicated data circuit for your SIP trunks and voice traffic. Makes troubleshooting much simpler and keeps your telephony off your data network.

 

Are you using Direct routing with your SIP trunks terminated on an SBC or Microsoft Teams calling plans? Highly recommend Audiocodes SBC's. Compared with a Cisco SBC they're a breeze to configure and troubleshoot with.

[DammitKid]

We're using SBCs. Calling plans looked messy and expensive.

[DammitKid]

Depending on the switch, the terminology may change but I think this covers it:

 

On the Edge:

• Create vlan 50
  
• If its a dedicated port for a phone then you can untag the port, if its port for a phone that a PC also uses then you can tag the port with vlan and specify the vlan on the phone.
  
• tag vlan 50 on the uplink trunk to the core,
  

 

 

On the Core:

• Create vlan with a interface IP
  
• tag vlan 50 on the downlink trunk to the edge.
  
• Add a IP helper to point at the DHCP server,
  
• As for a route, depends whats already setup, if you're using a totally different IP scheme for DHCP then potentially
  

 

 

DHCP

Setup DHCP and use the vlan 50 IP as the gateway.

 

Thanks for confirming this, I wasn't as rusty as I thought I was. Everything is up and running now on a few switches, tested and have passthrough working. Just the rest of the sites now!