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3563 Views 7 Replies Latest reply: Feb 14, 2011 9:47 PM by Brian RSS

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VLan setting for IP phone and PC Network mix environment

Feb 14, 2011 6:36 AM

Jason Yam 5 posts since
May 18, 2009

All the PC in our company are connected to 1 switch and the switch still has many empty ports.  Now our company is planning to put IP phones into the environment.  The IP addresses which use for the phones are in the same subnet of the PC network.  My question are follow.

 

1. Do I need to create the vlan1 and vlan2 in the switch to separate the IP phones traffic and the PC traffic?

 

2.  As I know (I guess), the new Phone System for IP phone just have one RJ45 port for handling phones and computer traffic.  So how can I connect the Phone System to both vlan1 and vlan2?

 

3.  For the IP phone traffic, is it a boardcasting traffic or a unicasting traffic?

 

I have never setup vlan before, so I can said I have no knowedge for how to set it up.

 

 

Thanks

  • daniel 8 posts since
    Dec 12, 2010

    Jason,

     

    Yes, you will need to create a separate vlan for voice, so all the addresses in one subnet is not going to work well.  The Cisco ip phones I have seen have an RJ45 going in, and one going out to a PC.  If yours only has one, than it probably doesn't have the internal switch, meaning you can't hook a PC up to it anyway.  I'm guessing that phone traffic is unicast, I forget.  The config for the switch port should look something like this:

     

    interface FastEthernet0/8

    switchport mode access

    switchport voice vlan 50

    spanning-tree portfast

    mls qos trust device cisco-phone

     

    This is all coming from a newbie, so take it with a grain of salt until a more experienced member replies.

     

    D

  • Nicholas Ong 94 posts since
    Jun 28, 2008

    Hi jason,

     

    There's a thick chapter of that in the CCDA course so I'll start with some quick tips.

    1&2 Yes.  You need 2 VLANs for the routing.  Usual configuration is that there'll be a 802.1q travelling to the Cisco IP phone and from there the VLAN is split up with the switch providing another VLAN to your PC connection.

    3.  I would say unicast for most applications.

     

    Also, you might want to take note if your switch support power over ethernet (POE)?  That is basic requirement in order to use Cisco IP phones~ otherwise, you'd need models with additional DC adapter (more wires!)

     

    I would think it'd be better for you to go your local library to get one CCDA book or purchase one.  Alternatively, try Cisco website for more information.

     

    Hope to Help. =)

     

    Nicholas Ong

  • Nicholas Ong 94 posts since
    Jun 28, 2008

    Hi Jason,

     

    the dot1q trunk serves that purpose of transporting multiple VLAN over the link.

     

    Cheers.

     

    Nicholas Ong

  • Jared 5,498 posts since
    Jul 27, 2008

    1. Do I need to create the vlan1 and vlan2 in the switch to separate the IP phones traffic and the PC traffic?    yes.

     

    2.  As I know (I guess), the new Phone System for IP phone just have one RJ45 port for handling phones and computer traffic.  So how can I connect the Phone System to both vlan1 and vlan2?  If the phone has only one port, you can't.  That is not a phone you want.

     

    3.  For the IP phone traffic, is it a boardcasting traffic or a unicasting traffic?   unicast traffic.

     

    I am actually doing a demo for a phone system myself.  Looking into ShorTel and Cisco.  One thing I have discovered with other VoIP vendors is that typically, the phone will boot into the data vlan and depend on a DHCP option.  That Option will tell the phone to tag traffic and what vlan to tag the voice traffic to.  The phone then reboots and joins the voice vlan that it was told about during the first reboot.

     

    This setup requires that you have both a tagged and untagged vlan on the same switchport.  I really don't care for this set up too much because it would allow an intruder to vlan hop to the voice vlan and cause issues.

     

    The Cisco method is using CDP to have the switch and phone negotiate the voice vlan.  Also, LLDP can be used in place of CDP for those mixed vendors that support LLDP-MED.

  • Brian 2,971 posts since
    Aug 17, 2009

    Aloha Jason,

     

    In regards to your questions.

     

    1. Do I need to create the vlan1 and vlan2 in the switch to separate the IP phones traffic and the PC traffic?

     

    Answer: No, not necessarily.  The creation of a separate voice Vlan is not required.  The default condition for every switch port is "None", where both the voice and data Vlans are untagged and share the same access Vlan.  However, it is  best practice to separate the traffic when deploying voice and date in a mixed network enviornment.  In fact, in order to separate the phone and PC traffic, the answer is yes.   In addition, if you choose to implement QoS then you want the traffic to be separated so as to assign different CoS values to the different traffic streams.

     

     

    2.  As I know (I guess), the new Phone System for IP phone just have one RJ45 port for handling phones and computer traffic.  So how can I connect the Phone System to both vlan1 and vlan2?

     

    Answer: Most Cisco IP phones have a built in 3-port switch.  How you connect the phone system depends on which one of the four voice vlan methods you choose.  Typically you connect the switch port to the network port on the IP phone.  The PC connects to the second RJ-45 port on the IP phone (labeled phone + sw or LAN).  You then need to select one of four voice vlan configuration methods.  Refer to the new SWITCH OCG page 310 for the different methods.

     

     

    3.  For the IP phone traffic, is it a boardcasting traffic or a unicasting traffic?

     

    Answer: Both.  In the initial phase of setup and configuration you will see broadcast traffic as the phone requests an IP address from the DHCP server.  Most traffic, once setup and configuration is complete, is primarily unicast.

     

    If you have never done this before, I would highly suggest you research and read up on the topic.  Some good sources are CCNA Voice OCG, SWITCH OCG, and Cisco's web site.  Best of luck to you.

     

    HTH

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