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This Question is Not Answered 1 Correct Answer available (4 pts) 2 Helpful Answers available (2 pts)
1671 Views 2 Replies Latest reply: May 4, 2012 1:09 AM by Daniel RSS

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Dual Ring Topology

May 1, 2012 7:31 AM

Tamer 19 posts since
Jan 11, 2012

Hello ,

 

I have found this questions and two diffecrent resources answers it differently


In which circumstance are multiple copies of the same unicast frame likely to be transmitted in a switched LAN?

A. after broken links are re-established
B. in an improperly implemented redundant topology
C. when upper-layer protocols require high reliability
D. during high traffic periods
E. when a dual ring topology is in use

 

 

 

One resource says the answer is B , as improperly implemnted redundant tolobplgy means STP is not in use

 

and another resource says its E

 

 

Can Anyone help me which one is the moree corrrect answer ? B or E ?

  • CiscoLoco - CCNP 956 posts since
    Feb 11, 2009
    Currently Being Moderated
    1. May 1, 2012 7:33 AM (in response to Tamer)
    Re: Dual Ring Topology

    A dual ring topology in its self doesnt mean you are going to have multiple copies of the same unicast frame, aka loops, it just allows the possibility if its not configured properly.  In my opinion the MUCH better answer is B like a spanning tree misconfiguration on a redundant network.

  • Daniel 197 posts since
    Jul 21, 2011
    Currently Being Moderated
    2. May 4, 2012 1:09 AM (in response to Tamer)
    Re: Dual Ring Topology

    Hi Tamer,

     

    Which certification are you studying for? Reading the question it clearly states:

     

    "...multiple copies of the SAME unicast frame LIKELY to be transmitted in a switched LAN?"

     

    If you're studying for the latest CCNA version, it's very very dull information regarding Ring topologies...it's as you may have noticed focused on Ethernet and Star topologies.

     

    I agree with CiscoLoco, answer B is correct because STP is most likely not enabled.

     

    Reason: It says in the question that it's using a unicast frame. Then based on the CCNA curriculum it's ethernet, as token ring uses another type of frame called "Token Frame" and also uses Active monitor/standby monitor stations to detect multiple token frames.

     

     

    Edit: I may (have!!) expressed myself a bit....confusing, so to avoid confusion....token ring uses a different technique than ethernet and stations are added based on a 5-phase process before they can participate in the ring. Token ring still uses broadcast, unicast and multicast - just wanted to make that clear Tamer ! So to not go into details, it's much much more likely a L2 loop will occur in a Ethernet switched network without STP enabled than it it is in a dual token ring topology but it Can occur and STP should be enabled.

     

    -Daniel

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