+ Reply to Thread
Results 1 to 9 of 9
  1. Senior Member
    Join Date
    May 2005
    Location
    Sydney, Australia
    Posts
    805

    Certifications
    CCNA, CCNP, CCIE#38186(R&S), JNCIA-JUNOS, JNCIS-SEC, JNCIP-SEC, JNCIS-ENT, F50-531, F50-533
    #1

    Default spanning tree porfast trunk?

    Whats the deal with the spanning tree porfast trunk command?

    I can't find a lot of information on it?

    Seems to be a bit confusing to me, since you couldnt't normally enable portfast on a trunk port.

    Cheers.
    Reply With Quote Quote  

  2. SS -->
  3. Member
    Join Date
    May 2006
    Location
    Midwest
    Posts
    80

    Certifications
    CNE, CCNA, CCNA Voice, CCNP, CCIP, CCNP-Voice
    #2
    I found this link, but can't really come up with a reason you'd want to put a trunk port into portfast mode:
    http://www.cisco.com/en/US/docs/swit...html#wp1070681
    Reply With Quote Quote  

  4. nel
    nel is offline
    Senior Member
    Join Date
    Jun 2006
    Location
    Australia
    Posts
    2,847

    Certifications
    A+ , Network+, MCSA 2003, CCENT, CCNA, CCDA, CCNP, CCDP, JNCIA-JunOS, JNCIS-ENT, Bsc(hons) & Msc Degree
    #3
    Its too enable portfast on trunk ports. we use it when connecting voip phones and clients to access switches when using a trunk
    Reply With Quote Quote  

  5. Netlurker cisco_trooper's Avatar
    Join Date
    Aug 2007
    Posts
    1,420

    Certifications
    CCNP Security, ASA Specialist, Firewall Security Specialist, IOS Security Specialist, IPS Specialist, VPN Security Specialist
    #4
    Yep, another real world example of this would be when trunking VLANs over to a VM environment....
    Reply With Quote Quote  

  6. Senior Member
    Join Date
    May 2005
    Location
    Sydney, Australia
    Posts
    805

    Certifications
    CCNA, CCNP, CCIE#38186(R&S), JNCIA-JUNOS, JNCIS-SEC, JNCIP-SEC, JNCIS-ENT, F50-531, F50-533
    #5
    Quote Originally Posted by nel
    Its too enable portfast on trunk ports. we use it when connecting voip phones and clients to access switches when using a trunk
    I thought an access port is normally used for voice VLANs... (i'm a bit rusty so i could be wrong)
    Reply With Quote Quote  

  7. Went to the dark side.... Moderator networker050184's Avatar
    Join Date
    Jul 2007
    Posts
    11,645

    Certifications
    CCNA, CCNP, CCIP, JNCIA-JUNOS, JNCIS-SP, JNCIP-SP, MCA200
    #6
    Quote Originally Posted by rakem
    I thought an access port is normally used for voice VLANs... (i'm a bit rusty so i could be wrong)
    An access port is in a single VLAN. If you use a voice and data VLAN on a port then it is a trunk ie it carries traffic for more than one VLAN.
    An expert is a man who has made all the mistakes which can be made.
    Reply With Quote Quote  

  8. Senior Member
    Join Date
    May 2005
    Location
    Sydney, Australia
    Posts
    805

    Certifications
    CCNA, CCNP, CCIE#38186(R&S), JNCIA-JUNOS, JNCIS-SEC, JNCIP-SEC, JNCIS-ENT, F50-531, F50-533
    #7
    Quote Originally Posted by networker050184
    Quote Originally Posted by rakem
    I thought an access port is normally used for voice VLANs... (i'm a bit rusty so i could be wrong)
    An access port is in a single VLAN. If you use a voice and data VLAN on a port then it is a trunk ie it carries traffic for more than one VLAN.
    yea but you don't actually configure it to be a trunk with the switchport mode trunk command do you?

    from cisco:
    "You should configure voice VLAN on switch access ports; voice VLAN is not supported on trunk ports. You can only configure a voice VLAN on Layer 2 ports"


    Plus portfast is automatically enabled when you configure a port for a voice vlan.

    http://www.ciscosystems.com/en/US/do...html#wp1033944
    Reply With Quote Quote  

  9. Village Idiot dtlokee's Avatar
    Join Date
    Mar 2007
    Location
    NJ
    Posts
    2,389

    Certifications
    CCIE #19991 R+S, CCNA, CCNP, CCIP, CCVP, CCSP, CCSI, MCSE NT4.0, 2000, 2003, + Messaging and Security, MCDBA, MCSD, MCAD
    #8
    Yes the correct way to configure a voice VLAN is to set the port as access and use the "switchport voice vlan" command along with spanning tree portfast.

    The "old way" was to configure the switchport as trunk, modify the allowed VLAN list to only allow the data VLAN and the voice VLAN, configure the "switchport voice vlan" command. The issue with this configuration is that portfast won't work on an interface configured this way. Spanning-tree portfase trunk was introduced later (I don't remember when). I have seen engineers turn off spanning tree on the access layer switches and use routed uplinks to the distribution layer to avoid loops. It's far more complex than it need be and is not the best method.

    The only good case I have seen for portfast trunk is putting the IPSec SPA in a 6500, there is a case where you need to build a trunk to the SPA but also want it to utilize portfast.
    Reply With Quote Quote  

  10. Senior Member
    Join Date
    May 2005
    Location
    Sydney, Australia
    Posts
    805

    Certifications
    CCNA, CCNP, CCIE#38186(R&S), JNCIA-JUNOS, JNCIS-SEC, JNCIP-SEC, JNCIS-ENT, F50-531, F50-533
    #9
    Yea, the reason i asked is because i have just started a new job and while looking through some switches almost all of them have the spanning-tree portfast trunk command on them
    Reply With Quote Quote  

+ Reply to Thread

Social Networking & Bookmarks