Announcement

Collapse
No announcement yet.

Separate data and voice networks

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Separate data and voice networks

    Without writing a novel about why, let me just say that we are currently thinking about tearing out our Cisco IP Phone system and replacing it with a shoretel System. We have found, as you could presume, that Cisco can network their phone system nicely but seem to lack in the creature comfort area. Shoretel seems to have a great phone product, but, as we are realizing in the design phase, they can't network worth $h.... I have to say that we don't actually have a whole lot of vendors here in western NY and our experiences may be due to lack of knowledge by the vendors.

    ANYWAY, if you are still reading, Cisco phone traffic is inherently tagged therefore if you set a voice vlan on your switches, the traffic is separated. We have been told that the shoretel system isn't inherently tagged and whenever the phone reboots, it looses its tagging.

    Where I am going with this is that we have multiple networks now for geo sites and voice
    X.X.1.X data site1
    X.X.3.X data site2
    X.X.4.X data site3
    X.X.5.X voice over all sites

    Shoretel tells me they have a hard time traversing all of the networks and that we could either hard code all of there phones so they aren't DHCP or put all of my sites on one network so they don't have a problem getting an IP address.

    Please confirm how wrong this is......

    Should I even consider this? The slowest connection between sites is a point to point T1, the other is a Gig fiber connection.

    Thanks,

    Marc
    Thank you,

    Marc

  • #2
    Re: Separate data and voice networks

    I have just been told that the Cisco IP phones use cdp to negoitiate which vlan to go to. They do not use the tagging as I suspected.

    If this is the case, what does the tagging do?

    Sorry, just learning about this stuff.
    Thank you,

    Marc

    Comment


    • #3
      Re: Separate data and voice networks

      Hi Marc,

      Yes, I have heard that Cisco phones need switches with CDP for a number of features. This led me to believe that if you use Cisco voip, it is very likely that you will use Cisco switches because only they have CDP.

      So is the tagging for QoS? That is my guess.

      About the shoretel system, are they proposing putting a system at each remote site or just one at the central site? I begin to loose faith in someone who says that "our phones have a hard time traversing multiple networks". I mean, that is what VoIP does. What do they mean "a hard time"?

      It wouldn't be possible to put sites connected via routers on a flat network (one network) unless you were bridging them all and you don't want to do that.

      In my company, we seriously evaluated Cisco VoIP. I wanted it badly but when compared to the competition, Cisco just seemed so darn complex - overly complex. I figured I would have to hire a new person just to manage it. We decided upon 3Com NBX systems because they are self contained and simple to configure. Now we are looking at Asterisk, the open source phone system. I will be testing that soon. I have never looked at Shoretel.
      David Davis - Petri Forums Moderator & Video Training Author
      Train Signal - The Global Leader in IT Video Training
      TrainSignalTraining.com - Free IT Training Products
      Personal Websites: HappyRouter.com & VMwareVideos.com

      Comment


      • #4
        Re: Separate data and voice networks

        Cisco phones use CDP to discover the voice and data vlan dot1q tags, but they also use CDP to request the correct level of power if the switch is PoE.

        Tagging of packets in a Cisco IP phone will default to CS5 for voice and CS3 for singalling. You need to make sure you configure the switch to trust QoS or the packets can be rewritten to CS0 or best efforts. It is very important to get this right if you are considering G.729 codec's over a WAN. Make sure the WAN routes have a priority LLQ QoS policy installed and you size the number of calls over the link.

        J.

        Comment


        • #5
          Re: Separate data and voice networks

          Hi jezster,
          Thanks for your post! We could use the help of someone with valuable Cisco VOIP knowledge around here!
          I am going to increase your repution points.
          David
          David Davis - Petri Forums Moderator & Video Training Author
          Train Signal - The Global Leader in IT Video Training
          TrainSignalTraining.com - Free IT Training Products
          Personal Websites: HappyRouter.com & VMwareVideos.com

          Comment


          • #6
            Re: Separate data and voice networks

            Sorry, I haven't posted on this in awhile. I thought I had it figured out. I am close but can't get both vlans to get along on the same port. Here is the scoop.

            Shoretel uses the dot1q tagging so that both the phone and PC can live on one port. The recommend this setup:

            interface FastEthernet0/4
            description : Link to PC on HR VLAN + ShoreTel IP Phone
            switchport mode trunk
            switchport trunk encapsulation dot1q
            switchport trunk native vlan 20 (20 being the DATA VLAN)

            When I try this, and manually set the tagging/vlan ID 5 on the phone, the phone will not receive a VL 5 IP.

            If I set the port like this:

            interface FastEthernet0/45
            switchport trunk encapsulation dot1q
            switchport trunk native vlan 2
            switchport trunk allowed vlan 5
            switchport mode trunk

            the phone will get a VL 5 ip, but obviously the PC can't get a VL 2 IP since it isn't allowed.

            If I set it up like this:

            interface FastEthernet0/45
            switchport trunk encapsulation dot1q
            switchport trunk native vlan 2
            switchport trunk allowed vlan 2,5
            switchport mode trunk

            The phone will not get a VL 5 ip address and the PC gets a VL 2 IP.

            Why can't I get both VLANs to work on the same port?

            I have a feeling it might be my DHCP not traversing my network correctly, but it traverses fine if only VL 5 is selected for a port.

            ...just moved this post to another existing thread http://forums.petri.com/showthread.php?t=13613
            Last edited by tnshurtm; 2nd April 2007, 19:23.
            Thank you,

            Marc

            Comment

            Working...
            X