MAC addressing help

remerolleremerolle ■■■□□□□□□□Posts: 72Member ■■■□□□□□□□
I am having issues with mac address/frame forwarding. I was wondering if there were any good tutorials out there to help me out with figuring out which ports a frame would go out if it had a destination address of x.


  • mobri09mobri09 Posts: 723Users Awaiting Email Confirmation
    The Cisco Press Intro book covers that topic like no other. I recommend this book.
  • NetstudentNetstudent Posts: 1,694Member
    It would take the spanning-tree path from switch to switch untill it got to the destination switch, in which case the frame would be forwarded to the corresponding interface. If there are no loops or redundancy, then there are no spanning-tree paths. If there are no loops, then the frame will take a linear path straight to the switch that the host resides. If there are no loops AND you have switches daisy chained together, the interfaces that connect the two switches will have numerous MAC's associated with those interfaces.

    For instance if switchA was connected to switchB from A fa0/1 <----> fa0/1 B. SwitchA would have all the host's MAC addresses on it's fa0/1 that were connected to switchB. And vice versa. That way when a frame traverses switchA that is destined for a host on switchB, then switchA can forward the frame on to switchB. If the MAC hasn't been learned yet, then the frame will be broadcasted. Read up on forward/filter decision making AND MAC learning. Have Fun!!!!
    There is no place like BUT is my away from!
  • mikej412mikej412 Posts: 10,090Member
    Maybe this VLANS VTP STP Cisco Flash Tutorials thread could be of some use....

    Anyone remember if Cisco has a "Bridging" flash presentation? A switch is just a multi-port bridge... and I remember one from the Cisco Network Academy.

    There is the Managing Mac Address table e-Lab over in the CCNA Prepcenter (create your free account if you haven't already done so).

    Ah Ha! maybe this Cisco How LAN Switches Work doc -- which includes flash animation. :D
    :mike: Cisco Certifications -- Collect the Entire Set!
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