Separate VLAN for VOIP and data?

Discussion in 'UK VOIP' started by Rob Nicholson, Jan 18, 2006.

  1. We're moving to a new office soon so we're re-networking and taking the
    opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    and data traffic into two separate LANs?

    Thanks, Rob.
    Rob Nicholson, Jan 18, 2006
    #1
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  2. Rob Nicholson

    Andrew Crane Guest

    "Rob Nicholson" <rob_nicholson@nospam_informed-direct.com> wrote in message
    news:dqlh5k$fkj$1$...
    > We're moving to a new office soon so we're re-networking and taking the
    > opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    > and data traffic into two separate LANs?


    This kind of negates the whole purpose of VOIP. I would however prioritise
    VOIP traffic out of your network.

    Regards
    Andrew


    --
    Inweb Networks. Quality internet and telecoms services
    Sales: 08000 612222 Support: 08704322222. http://www.inweb.co.uk
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    Andrew Crane, Jan 18, 2006
    #2
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  3. Rob Nicholson

    Sauron Guest

    "Rob Nicholson" <rob_nicholson@nospam_informed-direct.com> wrote in message
    news:dqlh5k$fkj$1$...
    We're moving to a new office soon so we're re-networking and taking the
    opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    and data traffic into two separate LANs?

    Thanks, Rob.

    -----------------------------------

    You could either setup QOS to ensure that the calls get the bandwidth they
    need, and or you can use VLAN, I would use QOS because when VOIP aint in use
    the bandwidth can be used else where.
    Sauron, Jan 18, 2006
    #3
  4. Rob Nicholson wrote:
    > We're moving to a new office soon so we're re-networking and taking the
    > opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    > and data traffic into two separate LANs?


    Not unreasonable. A site I work at splits the VOIP traffic off the SDSL
    router using a VLAN arrangement directly to the VOIP card in the switch.
    The rest of the traffic passes to a series of Nokia switch/firewalls.
    Colin Forrester, Jan 18, 2006
    #4
  5. Rob Nicholson

    Tim Bray Guest

    Rob Nicholson wrote:
    > We're moving to a new office soon so we're re-networking and taking the
    > opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    > and data traffic into two separate LANs?


    That is the Cisco way of doing it to sell lots of vlan capable switches. :)


    It doesn't make that much difference unless you are likely to saturate
    your local network. Most switches will let you set the priority of the
    packet using part of the vlan indentifier.



    Tim
    Tim Bray, Jan 18, 2006
    #5
  6. > Not unreasonable. A site I work at splits the VOIP traffic off the SDSL
    > router using a VLAN arrangement directly to the VOIP card in the switch.
    > The rest of the traffic passes to a series of Nokia switch/firewalls.


    That's the kind of thing we're thinking about.

    Rob.
    Rob Nicholson, Jan 18, 2006
    #6
  7. > need, and or you can use VLAN, I would use QOS because when VOIP aint in
    > use
    > the bandwidth can be used else where.


    Is QOS a packet level kind of thing?

    Reason I ask is that we sometimes have a little local switch on the desk
    when network ports are limited. Therefore the VOIP and data traffic for
    (say) four PCs & telephones would be travelling up the same wire to the
    switch. Would the QoS feature on the switch still work/help here?

    Thanks, Rob.
    Rob Nicholson, Jan 18, 2006
    #7
  8. Rob Nicholson

    alexd Guest

    Rob Nicholson wrote:

    > We're moving to a new office soon so we're re-networking and taking the
    > opportunity to switch to VOIP.
    > Is traditional wisdom (!)


    The traditional wisdom is to use Primary Rate ;-)

    > to split the VOIP and data traffic into two separate LANs?


    It's possible to achieve QoS without two separate LANs. Many VoIP phones [eg
    Mitels] come with a passthrough ethernet port, so that if you have a phone
    at each desk, and a workstation plugged into the phone, the phone
    prioritises the voice traffic over the data traffic. It's also a good idea
    to prioritise voice traffic going out of/into your network over your
    internet connection or whatever.

    alexd
    --
    <http://ale.cx/> (AIM:troffasky) ()
    18:53:02 up 2 days, 23:07, 2 users, load average: 0.08, 0.15, 0.15
    This is my BOOOOOOOOOOOOOOOOOOOOOMSTICK
    alexd, Jan 18, 2006
    #8
  9. Rob Nicholson

    IMPI Guest

    It is advisible to seperate voice and data traffic into seperate vlans.
    Even with Qos enabled you can still get distortion on the ip phones if they
    share the same vlan as the data vlan due to broadcast traffic.
    Regards
    IMPI


    "Rob Nicholson" <rob_nicholson@nospam_informed-direct.com> wrote in message
    news:dqlh5k$fkj$1$...
    > We're moving to a new office soon so we're re-networking and taking the
    > opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    > and data traffic into two separate LANs?
    >
    > Thanks, Rob.
    >
    IMPI, Jan 18, 2006
    #9
  10. > prioritises the voice traffic over the data traffic. It's also a good idea
    > to prioritise voice traffic going out of/into your network over your
    > internet connection or whatever.


    Ahh, that's useful to know. We're considering Swyx at the moment and they
    sell phones with two Ethernet ports. I thought this was just a way of saving
    network sockets (in effect a little two port switch) but if they also add
    prioritisation as well, then that's obviously better.

    We're not brave enough yet to go VOIP over the internet :) We'll be
    sticking with an ISDN-30 line for now.

    Thanks, Rob.
    Rob Nicholson, Jan 18, 2006
    #10
  11. > It is advisible to seperate voice and data traffic into seperate vlans.
    > Even with Qos enabled you can still get distortion on the ip phones if
    > they share the same vlan as the data vlan due to broadcast traffic.
    > Regards


    Thanks. We use Citrix for a lot of our users and that effects the situation
    somewhat in that the bandwidth of a terminal is relatively low but more
    constant. If somebody happens to copy/save/whatever a large file on the
    Citrix server, that happens across the gigabit LAN between the Citrix
    servers and the data/email server. You should see the look on a user's face
    when they send an 20MB email (from the shared drive) when connected to
    Citrix via a dial-up telephone line. For a VPN user, it's quite a shock. We
    always find it hard to explain how Citrix works :)

    Anyway, this means that we can do a calculation on the bandwidth needed for
    Citrix plus the phones in a far more accurate manner than a normal PC
    environment.

    Cheers, Rob.
    Rob Nicholson, Jan 18, 2006
    #11
  12. > The traditional wisdom is to use Primary Rate ;-)

    What's that then? :)

    Cheers, Rob.
    Rob Nicholson, Jan 18, 2006
    #12
  13. Rob Nicholson

    Jono Guest

    Rob Nicholson wrote:
    ||| The traditional wisdom is to use Primary Rate ;-)
    ||
    || What's that then? :)
    ||
    || Cheers, Rob.

    ISDN30e
    Jono, Jan 18, 2006
    #13
  14. > ISDN30e

    Phew - that's probably what we're sticking with. We're going to experiment
    with VOIP over the internet to call home workers but that's as far as we're
    going. Telephone is still too crucial to our business to risk quite that
    much.

    Cheers, Rob.
    Rob Nicholson, Jan 19, 2006
    #14
  15. Rob Nicholson

    Ian Guest

    "Rob Nicholson" <rob_nicholson@nospam_informed-direct.com> wrote in message
    news:dqlh5k$fkj$1$...
    > We're moving to a new office soon so we're re-networking and taking the
    > opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    > and data traffic into two separate LANs?
    >
    > Thanks, Rob.
    >


    Hi Rob
    That is one option. And is used by many large sites.
    the other option is to get the QOS setup correctly so the phones tag the
    packets correctly and then make sure all the switches are setup to
    prioritise this traffic.
    Still wont help if you have a broadcast storm, But will let you use dual
    port phones.

    Ian
    www.cyber-cottage.co.uk
    Ian, Jan 19, 2006
    #15
  16. Rob Nicholson

    Andrew Crane Guest

    "Rob Nicholson" <rob.nicholson@nospam_unforgettable.com> wrote in message
    news:8Svzf.1272$...
    > > need, and or you can use VLAN, I would use QOS because when VOIP aint in
    > > use
    > > the bandwidth can be used else where.

    >
    > Is QOS a packet level kind of thing?
    >
    > Reason I ask is that we sometimes have a little local switch on the desk
    > when network ports are limited. Therefore the VOIP and data traffic for
    > (say) four PCs & telephones would be travelling up the same wire to the
    > switch. Would the QoS feature on the switch still work/help here?


    No - however, presumably you are connected at 100Mbps and I very much doubt
    you will be doing anything that will interfere with a call. If the call
    quality degrades, stop transferring data.

    If the four PCs are talking amongst themselves then being a switch, your
    uplink port will not be used for this data.

    By far your biggest bottleneck is your connection to the net unless you have
    at least a 100Mbps connection to the net.

    By splitting off two networks and running them both into this bottleneck you
    aren't going to achieve anything.

    Is your VOIP not working well or is this just a design thing?

    Regards
    Andrew
    Andrew Crane, Jan 19, 2006
    #16
  17. Rob Nicholson

    Andrew Crane Guest

    "IMPI" <> wrote in message
    news:W_wzf.1292$...
    > It is advisible to seperate voice and data traffic into seperate vlans.
    > Even with Qos enabled you can still get distortion on the ip phones if

    they
    > share the same vlan as the data vlan due to broadcast traffic.
    > Regards
    > IMPI


    Why are you broadcasting? I can't see any need to be broadcasting around a
    LAN other than the odd ARP. If your broadcast traffic is an issue, it's time
    to go spring cleaning.

    Regards
    Andrew


    --
    Inweb Networks. Quality internet and telecoms services
    Sales: 08000 612222 Support: 08704322222. http://www.inweb.co.uk
    E1 call share. 0800, 0845 and 0870 numbers - best rates. Resellers welcome
    Andrew Crane, Jan 19, 2006
    #17
  18. > By far your biggest bottleneck is your connection to the net unless you
    > have
    > at least a 100Mbps connection to the net.
    >
    > By splitting off two networks and running them both into this bottleneck
    > you
    > aren't going to achieve anything.


    The net doesn't come into our equation at all - this is an internal PBX.

    > Is your VOIP not working well or is this just a design thing?


    It doesn't exist yet - we're planning installation of a new VOIP.

    Cheers, Rob.
    Rob Nicholson, Jan 19, 2006
    #18
  19. Rob Nicholson

    Alan Ramsay Guest

    Ian wrote:
    > "Rob Nicholson" <rob_nicholson@nospam_informed-direct.com> wrote in message
    > news:dqlh5k$fkj$1$...
    >> We're moving to a new office soon so we're re-networking and taking the
    >> opportunity to switch to VOIP. Is traditional wisdom (!) to split the VOIP
    >> and data traffic into two separate LANs?
    >>
    >> Thanks, Rob.
    >>

    >
    > Hi Rob
    > That is one option. And is used by many large sites.
    > the other option is to get the QOS setup correctly so the phones tag the
    > packets correctly and then make sure all the switches are setup to
    > prioritise this traffic.
    > Still wont help if you have a broadcast storm, But will let you use dual
    > port phones.
    >
    > Ian
    > www.cyber-cottage.co.uk
    >
    >
    >
    >

    Not quite sure why not using VLAN tagging would allow you to use the
    port on the phone, but by using VLAN tagging you can't.

    Simply set the switches to allow both untagged and tagged VLAN traffic,
    then leave the PCs in the default VLAN (ie untagged), and set the Phones
    to be tagged with VLAN2 for example; that way you can use the passthru
    port for the PC AND split VOIP & Data over two VLAN's.

    Avaya have a VOIP setup guide available at
    http://support.avaya.com/elmodocs2/comm_mgr/r3/IP_GUIDE_3.0.pdf

    Take a look at the recommendations on page 16 and point 2 on page 22
    regarding "Multi-VLAN Ethernet Switch"

    Regards

    Alan
    Alan Ramsay, Jan 19, 2006
    #19
  20. Rob Nicholson

    alexd Guest

    Rob Nicholson wrote:

    > We use Citrix for a lot of our users and that effects the
    > situation somewhat in that the bandwidth of a terminal is relatively low
    > but more constant. If somebody happens to copy/save/whatever a large file
    > on the Citrix server, that happens across the gigabit LAN between the
    > Citrix servers and the data/email server.


    Similar-ish sort of thing here; Mitel 5220 at each desk with a Wyse RDP
    terminal connected through it. One set of wiring, zero problems. Apart from
    the fact that we're using Windows, but that's another story ;-)

    alexd
    --
    <http://ale.cx/> (AIM:troffasky) ()
    20:18:02 up 4 days, 33 min, 2 users, load average: 0.44, 0.56, 0.67
    This is my BOOOOOOOOOOOOOOOOOOOOOMSTICK
    alexd, Jan 19, 2006
    #20
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