Will Cisco routers help my VoIP issue...

Discussion in 'Cisco' started by Default User, Apr 13, 2009.

  1. Default User

    Default User Guest

    Hi,

    What I have is two office phone systems (2 locations) and 5 IP phones. The
    two office systems communicate with each other over IP and so do the 5 IP
    phones. We have a T1 at each office. The 5 IP phones are at branch offices
    that have DSL.

    We are not current using Cisco routers and have in place some SonicWall
    routers. We are experiencing voice quality issues and are thinking about
    switching to Cisco routers because of this.

    I have enabled QoS on the SonicWall routers as well as outgoing bandwdith
    management to limit the amount of bandwidth consumed by non-voice traffic.
    This made a huge improvement in voice quality although we are still not
    where we want to be.

    I have an IP phone and I can always hear people just fine. This would mean
    that outgoing traffic from our main office to me works great and that the
    outgoing bandwidth limiting of non-voice traffic is doing its job. The
    problem is that people are unable to hear my voice going back to that
    location. I have a theory on this which is that people at that location are
    consuming the incoming bandwidth and there isn't enough leftover for the
    incoming voice traffic.

    The question is - how do you limit incoming bandwidth? The SonicWall does
    have a feature to do this, but it makes the problem worse rather than
    better. I don't really see how you can throttle what is sent to you because
    once you have it, it has already been received.

    I guess there must be some sort of technique for throttling outgoing
    requests that can throttle the incoming packets for that type of traffic.
    Does Cisco utilize some sort of techniques like this?

    Questions:

    1. Do you think replacing our routers with Cisco routers would solve this
    problem? In other worse, does Cisco have some sort of technique for
    properly sharing voice and data on the same WAN connection in such a way
    that the data traffic will not cause problems for the voice traffic?

    2. I thought about putting the voice on its on dedicated WAN connection,
    but this will complicate the network configuration as well as have a service
    cost to it.

    3. I found something called a "traffic shaping bridge". Would this be a
    possible solution worth looking at?

    Thanks,

    Alan
     
    Default User, Apr 13, 2009
    #1
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  2. Default User

    bod43 Guest

    On 13 Apr, 15:51, "Default User" <> wrote:
    > Hi,
    >
    > What I have is two office phone systems (2 locations) and 5 IP phones.  The
    > two office systems communicate with each other over IP and so do the 5 IP
    > phones.  We have a T1 at each office.  The 5 IP phones are at branch offices
    > that have DSL.
    >
    > We are not current using Cisco routers and have in place some SonicWall
    > routers.  We are experiencing voice quality issues and are thinking about
    > switching to Cisco routers because of this.
    >
    > I have enabled QoS on the SonicWall routers as well as outgoing bandwdith
    > management to limit the amount of bandwidth consumed by non-voice traffic..
    > This made a huge improvement in voice quality although we are still not
    > where we want to be.
    >
    > I have an IP phone and I can always hear people just fine.  This would mean
    > that outgoing traffic from our main office to me works great and that the
    > outgoing bandwidth limiting of non-voice traffic is doing its job.  The
    > problem is that people are unable to hear my voice going back to that
    > location.  I have a theory on this which is that people at that location are
    > consuming the incoming bandwidth and there isn't enough leftover for the
    > incoming voice traffic.
    >
    > The question is - how do you limit incoming bandwidth?  The SonicWall does
    > have a feature to do this, but it makes the problem worse rather than
    > better.  I don't really see how you can throttle what is sent to you because
    > once you have it, it has already been received.
    >
    > I guess there must be some sort of technique for throttling outgoing
    > requests that can throttle the incoming packets for that type of traffic.
    > Does Cisco utilize some sort of techniques like this?
    >
    > Questions:
    >
    > 1.  Do you think replacing our routers with Cisco routers would solve this
    > problem?  In other worse, does Cisco have some sort of technique for
    > properly sharing voice and data on the same WAN connection in such a way
    > that the data traffic will not cause problems for the voice traffic?
    >
    > 2.  I thought about putting the voice on its on dedicated WAN connection,
    > but this will complicate the network configuration as well as have a service
    > cost to it.
    >
    > 3.  I found something called a "traffic shaping bridge".  Would this be a
    > possible solution worth looking at?
    >


    You obviously cannot influence the incoming internet traffic
    unless the ISP and all ISPs between the locations honour
    the QoS bits *AND* they are prepared to do QoS
    on your traffic. As far as I know there are no ISPs that
    do this but I am not sure.

    There is however one trick that you might consider
    for controlling incoming traffic from the internet.
    Most internet traffic is TCP and TCP self regulates its
    use of bandwidth if there is a restriction in the path. So if
    you say have a 2M DSL you could in principle
    restrict the incoming non-voice to 1.5M leaving
    512k for voice which might be enough for two
    simultaneous calls. You need to check the
    exact values yourself.

    If you are doing other UDP (peer to peer systems
    seem to like UDP but will also use TCP) then this
    may not work so well but all web browsing is TCP.

    It does not matter whether you restrict the non-voice
    traffic heading into the router from the outside
    or heading to the inside from the router.

    This *does* work. I have implemented it myself.
    Of course you lose the 512k for non-voice traffic
    but that is something that you may be able to
    live with.

    Cisco routers have the tools to implement the
    above scheme.
     
    bod43, Apr 14, 2009
    #2
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  3. Default User

    Stephen Guest

    On Mon, 13 Apr 2009 09:51:46 -0500, "Default User"
    <> wrote:

    >Hi,
    >
    >What I have is two office phone systems (2 locations) and 5 IP phones. The
    >two office systems communicate with each other over IP and so do the 5 IP
    >phones. We have a T1 at each office. The 5 IP phones are at branch offices
    >that have DSL.
    >
    >We are not current using Cisco routers and have in place some SonicWall
    >routers. We are experiencing voice quality issues and are thinking about
    >switching to Cisco routers because of this.
    >
    >I have enabled QoS on the SonicWall routers as well as outgoing bandwdith
    >management to limit the amount of bandwidth consumed by non-voice traffic.
    >This made a huge improvement in voice quality although we are still not
    >where we want to be.
    >

    1 way to improve on this is remove the sharing since QoS only matters
    when there is contention.
    it may be more cost effective to keep just your IP voice on 1
    dedicated Internet link per site (depending on the cost of a 2nd
    broadband link in your area).

    however it is worth remembering that IP voice will only be consistent
    and reliable under all conditions if there is QoS end to end - the
    reality is that doesnt exist on the Internet in the general case.

    1 alternative here is alternative conventional voice providers - my UK
    calls to non mobiles cost connection charge, but no cost / min, and no
    monthly fee. USA calls run 0.5p / min.

    I have given up on VoIP on Internet at home for now since the cost
    reduction just doesnt over the hassle.

    So - maybe you need to think about how much this "cheap" voice service
    is really costing you in terms of frustration, repeat calls and
    possibly annoying your users and customers.

    >I have an IP phone and I can always hear people just fine. This would mean
    >that outgoing traffic from our main office to me works great and that the
    >outgoing bandwidth limiting of non-voice traffic is doing its job. The
    >problem is that people are unable to hear my voice going back to that
    >location. I have a theory on this which is that people at that location are
    >consuming the incoming bandwidth and there isn't enough leftover for the
    >incoming voice traffic.
    >
    >The question is - how do you limit incoming bandwidth? The SonicWall does
    >have a feature to do this, but it makes the problem worse rather than
    >better. I don't really see how you can throttle what is sent to you because
    >once you have it, it has already been received.
    >
    >I guess there must be some sort of technique for throttling outgoing
    >requests that can throttle the incoming packets for that type of traffic.
    >Does Cisco utilize some sort of techniques like this?
    >
    >Questions:
    >
    >1. Do you think replacing our routers with Cisco routers would solve this
    >problem? In other worse, does Cisco have some sort of technique for
    >properly sharing voice and data on the same WAN connection in such a way
    >that the data traffic will not cause problems for the voice traffic?
    >
    >2. I thought about putting the voice on its on dedicated WAN connection,
    >but this will complicate the network configuration as well as have a service
    >cost to it.
    >
    >3. I found something called a "traffic shaping bridge". Would this be a
    >possible solution worth looking at?
    >
    >Thanks,
    >
    >Alan
    >

    --
    Regards

    - replace xyz with ntl
     
    Stephen, Apr 14, 2009
    #3
  4. Default User

    Default User Guest

    Hi,

    >There is however one trick that you might consider
    >for controlling incoming traffic from the internet.
    >Most internet traffic is TCP and TCP self regulates its
    >use of bandwidth if there is a restriction in the path. So if
    >you say have a 2M DSL you could in principle
    >restrict the incoming non-voice to 1.5M leaving
    >512k for voice which might be enough for two
    >simultaneous calls. You need to check the
    >exact values yourself.


    It is a T1 connection and I have implemented outgoing bandwidth throttling
    for non-voice data at 50% of the connection. In theory this would split the
    1.344mbps to 672kbps for voice and 672kbps for data.

    Are you saying that because I've throttled the outgoing packets that this
    should do a decent enough job of throttling the incoming packets as well?

    I *think* the problem is getting packets INTO this main location. I don't
    want to throttle the data more, but I wonder if I throttle it a bit more if
    that would help until we find a better solution...

    Thanks,

    Alan
     
    Default User, Apr 14, 2009
    #4
  5. Default User

    alexd Guest

    Default User wrote:

    > 1. Do you think replacing our routers with Cisco routers would solve this
    > problem? In other worse, does Cisco have some sort of technique for
    > properly sharing voice and data on the same WAN connection in such a way
    > that the data traffic will not cause problems for the voice traffic?


    I think you need to work out the cause of your problems first, before
    throwing more hardware at it. Does the vendor of your phone system offer
    any guidance as to what kind of network configuration will work with your
    setup? Is there any debugging or diagnostics output from the PBX? What type
    of VoIP is it? One-way audio is a classic symptom of NAT issues with SIP.
    Do you have the SIP ALG enabled on the Sonicwall(s)? What kind of load is
    on your T1?

    > 2. I thought about putting the voice on its on dedicated WAN connection,
    > but this will complicate the network configuration as well as have a
    > service cost to it.


    One thing that is worth trying would be to eliminate as much from your setup
    as possible until the problem disappears, then re-add things until the
    problem recurs. For example, if you think the one-way audio is
    load-related, disconnect everything from behind the Sonicwall bar the PBX
    and re-test.

    --
    <http://ale.cx/> (AIM:troffasky) ()
    19:55:59 up 130 days, 21:07, 2 users, load average: 0.34, 0.20, 0.23
    My god, said I, with my one liquid eye, am I dreaming, or am I insane?
     
    alexd, Apr 14, 2009
    #5
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