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DHCP VOIP Without VLAN

Hello, We're in the beginning stages of rolling out IP phones and we want to use a different DHCP scope for phones as opposed to workstations. Our office is only roughly 40 users so I don't think VLANs are worth the effort so I wondering if someone with more knowledge on Sophos and just the process in general could provide some guidance to if this is possible and if so how to proceed. Thanks


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  • Hi,

    I aggree to my previous writers: you should work with different VLANs.

    According to your question: you can work with two different IP subnets in one LAN. If there's no routing instance between the subnets, only clients of the same subnet will see each other (VoIP see VoIP, workstations see workstations). But I think it is not possible to add two different DHCP ranges on the same LAN interface of the UTM. I'm also not sure if you can route between the subnets with one physical LAN interface. For this the interface must have two IP addresses, one of each subnet.

     

    Jas

  • Thanks for the answers.

    I'm not opposed to VLANs, I just wasn't sure for roughly 40 users that it would make a difference... which based on all the replies, seems like VLAN is the way to go.  Additionally, to be honest, while I understand the concept, I haven't designed one previously.   So with that said, hopefully I ask some more questions and provide some more details :

    • Due to the lack of drops at end user stations, we are planning on using the switch in the phones (this may change down the line as we expect to have work done on our home office and have multiple drops added)
    • We currently don't use VLANs, so with the knowledge that there won't be a different switch for phones, how would I establish what I imagine is two VLANS (data and voice)?
    • Our new VOIP system will be cloud based if that makes a difference
    • Can the Sophos UTM 220 be the DHCP for these two different scopes and understand how to provide each type of device their proper subnet

     Hopefully that all makes sense.

    Thanks in advance. 

  • VLANs serve a single purpose...security. That's it. If you NEED to separate your network because you can't have network devices "seeing" some other devices on your network, that is when you use VLANs. 

    I've setup many flat networks that included hundreds of VoIP phones without the use of a single VLAN and have yet to run into any issues that were a direct result of the internal network. In every case of a problem, the issue could be traced back to the ISP or destination or some point in between. Jitter and latency are your worst enemies for VoIP and if you have problems with those on your internal network, you've ether got bad infrastructure (ie: bad cabling, terminations, equipment) or a bad network design. Do yourself a favour and read item #5 here...

    betanews.com/.../

    I totally onboard with others in recommending you run separate drops for phone connections and don't use any phone's internal switch. They are garbage unless you pay huge money for the phones. 

    Empty Set said:
    Due to the lack of drops at end user stations, we are planning on using the switch in the phones (this may change down the line as we expect to have work done on our home office and have multiple drops added)

    This is likely to cause you many headaches.

    Empty Set said:
    We currently don't use VLANs, so with the knowledge that there won't be a different switch for phones, how would I establish what I imagine is two VLANS (data and voice)?

    VLANs are not a necessity unless for security separation as mentioned.

    Empty Set said:
    Our new VOIP system will be cloud based if that makes a difference

    Make sure you have your provider set you up with onsite testing units before you sign anything so you can see and experience how things work. This isn't a guarantee that things will work well and forever (internet routes change constantly so there's no guarantee that packets travelling one route will always travel that route), but it's a start.

    Empty Set said:
    Can the Sophos UTM 220 be the DHCP for these two different scopes and understand how to provide each type of device their proper subnet

    Yes, you simply have to setup a new interface you get to set the IP address for your gateway as well as netmask, then setup a new DHCP server on the UTM.

Reply
  • VLANs serve a single purpose...security. That's it. If you NEED to separate your network because you can't have network devices "seeing" some other devices on your network, that is when you use VLANs. 

    I've setup many flat networks that included hundreds of VoIP phones without the use of a single VLAN and have yet to run into any issues that were a direct result of the internal network. In every case of a problem, the issue could be traced back to the ISP or destination or some point in between. Jitter and latency are your worst enemies for VoIP and if you have problems with those on your internal network, you've ether got bad infrastructure (ie: bad cabling, terminations, equipment) or a bad network design. Do yourself a favour and read item #5 here...

    betanews.com/.../

    I totally onboard with others in recommending you run separate drops for phone connections and don't use any phone's internal switch. They are garbage unless you pay huge money for the phones. 

    Empty Set said:
    Due to the lack of drops at end user stations, we are planning on using the switch in the phones (this may change down the line as we expect to have work done on our home office and have multiple drops added)

    This is likely to cause you many headaches.

    Empty Set said:
    We currently don't use VLANs, so with the knowledge that there won't be a different switch for phones, how would I establish what I imagine is two VLANS (data and voice)?

    VLANs are not a necessity unless for security separation as mentioned.

    Empty Set said:
    Our new VOIP system will be cloud based if that makes a difference

    Make sure you have your provider set you up with onsite testing units before you sign anything so you can see and experience how things work. This isn't a guarantee that things will work well and forever (internet routes change constantly so there's no guarantee that packets travelling one route will always travel that route), but it's a start.

    Empty Set said:
    Can the Sophos UTM 220 be the DHCP for these two different scopes and understand how to provide each type of device their proper subnet

    Yes, you simply have to setup a new interface you get to set the IP address for your gateway as well as netmask, then setup a new DHCP server on the UTM.

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