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Portfast on wireless AP port

Discussion in 'General Cisco Certifications' started by mentman, Aug 12, 2009.

  1. mentman

    mentman Bit Poster

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    Hi,

    Is is safe interms of switching loops to use spanning-tree portfast on ports connecting wireless access points?

    Thanks
     
    Certifications: CCNA, CCENT, ITE, 642-812 BCMSN
    WIP: 642-901 BCSI
  2. r.h.lee

    r.h.lee Gigabyte Poster

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    mentman,

    Do you know if the wireless access point is using trunking?
     
    Certifications: MCSE, MCP+I, MCP, CCNA, A+
    WIP: CCDA
  3. bluelambda

    bluelambda New Member

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    My memory might be failing me (haven't deployed wireless in a while), but isn't the wireless access point a layer 2 device? Personally the only situation I would feel safe putting the port into portfast is when I connect the port to an end user (layer 3) device. For stuff like wireless bridges and other L2 devices I don't think it's right to enable portfast.

    That said, if the wireless AP is not physically cabled up to 2 ports at once I don't see how there can ever be a loop.

    Might be wrong about this one though :P
     
    Certifications: CCNA, CCNP, F5 SE (LTM)
  4. cisco lab rat

    cisco lab rat Megabyte Poster

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    It's fine to use "spanning-tree portfast"

    I do it all the time, provided that there is only on link from the AP to the switch
     
    Last edited: Aug 31, 2009
    Certifications: Yes I pretty much am!!
    WIP: Fizzicks Degree
  5. r.h.lee

    r.h.lee Gigabyte Poster

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    bluelambda,

    It depends on how many VLANs are configured on the Cisco Wireless Access Point. If you only have the single VLAN on the Cisco Wireless Access Point, then you might be able to use portfast on the upstream switch port. However, if you have 2 or more VLANs configured on the Cisco Wireless Access Point, then the link between the Cisco Wireless Access Point and the upstream switch must be a trunk, which means it shouldn't be using portfast.
     
    Certifications: MCSE, MCP+I, MCP, CCNA, A+
    WIP: CCDA
  6. cisco lab rat

    cisco lab rat Megabyte Poster

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    portfast is a mechanism used in spanning tree to instruct the protocol to bring the port into forwarding without having to transition through the listening and learning states. In other words to miniimise the time STP takes to converge

    If a the link between the AP and the switch is a trunk which is a port configured to carry frames for more than one VLAN those frames that travel up a trunk to the switch or down to the AP from the switch will not be switched back down the trunk down the "other" vlan/s.

    I have tested this this afternoon on my AP's with multiple vlans and it does not seem to cause any loops, no different to having switches connected in series like below

    switch------switch------switch-----switch

    In the network above you could turn off spanning tree (Not that you would) and the network will still function.

    My advice to you is do it for yourself and see for yourself what effects it has
     
    Certifications: Yes I pretty much am!!
    WIP: Fizzicks Degree

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