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This Question is Not Answered 1 Correct Answer available (4 pts) 2 Helpful Answers available (2 pts)
2665 Views 18 Replies Latest reply: Feb 23, 2014 11:04 PM by Paul RSS 1 2 Previous Next

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Non-Broadcast Multi-Access (NBMA)

Feb 20, 2013 12:33 AM

Krishna 770 posts since
Aug 24, 2011

Hi Experts,


What is a Non-Broadcast Multi-Access (NBMA) Network? Please provide any good examples of NBMA networks.

 

Krishna

  • Sey 1,393 posts since
    May 4, 2010
    Currently Being Moderated
    1. Feb 20, 2013 12:55 AM (in response to Krishna)
    Re: Non-Broadcast Multi-Access (NBMA)

    As the name implies, NBMA is a network that cannot broadcast frames. A well known example is Frame Relay.

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    2. Feb 20, 2013 1:03 AM (in response to Sey)
    Re: Non-Broadcast Multi-Access (NBMA)

    as sey mentioned above. yep frame relay is ain example of Non-Broadcast Multi Access.

     

    you can do broadcast on ip or mac based. but frame relar works on layer 2 dlci no. so no way to activate a broadcast in it.

     

    you can convert a broadcast into unicast when it enters in a frame-relay cloud.

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    4. Feb 20, 2013 2:09 AM (in response to Krishna)
    Re: Non-Broadcast Multi-Access (NBMA)

    as per your queries:

     

    1. Can we run frame relay in a Ethernet/Fastethernet interface?

     

    no, its a wan technology and can be used with serial interface.

     

    2. Does frame replay used MAC address?

     

    no. as serial interface does not have mac addresses. it uses DLCI no. instead of mac addreses which is locally significiant.

     

    3.If not MAC address is usedd, what will be the structure of the L2 frame?

     

    local dlci no. is used to map with destination ip address.

     

    http://www.techfest.com/networking/wan/frrel.htm

     

    4. Why we use frame relay?  Is it for WAN connections? Will it work in a LAN environment?

     

    its a wan technology. frame relay provides many benefits. check below link:

     

    http://www.wifinotes.com/computer-networks/what-is-frame-relay.html

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    6. Feb 20, 2013 3:12 AM (in response to Krishna)
    Re: Non-Broadcast Multi-Access (NBMA)

    yep it is.

     

    for more specific. between hosts there is a frame relay cloud and at every client end there is a frame relay switch.

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    8. Feb 20, 2013 4:59 AM (in response to Krishna)
    Re: Non-Broadcast Multi-Access (NBMA)

    The ISP who is providing the frame relay service will be giving the PVC numbers..right?

     

    when a pvc(logical circuit) is created by an ISP they will provide you 2 DLCI no. means the two end point of circuit. you need to by the dlci no.

     

    yep frame-realy is still used but not to that much extinct as it cannot be extended to a scenario like internet.

     

    you can ask as many as question you want because knowledge comes with doubts only.

     

    in MPLS the packet was tagged at every point. but in frame relay we uses DLCI no. which is locally significiant.

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  • Ramon G. 630 posts since
    Feb 10, 2011
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    10. Feb 20, 2013 7:48 PM (in response to Krishna)
    Re: Non-Broadcast Multi-Access (NBMA)

    The frame-relay mapping is made between the the remote end ip address and the local DLCI, so when a packet is sent from newyork DLCI 300 to the ip address x.x.x.x of london this packet is routed for the frame-relay switch to the local DLCI 100 of london.

    Is important to know that the DLCI number is locally significant.

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  • cadetalain 2,728 posts since
    Sep 18, 2008
    Currently Being Moderated
    12. Feb 28, 2013 12:23 AM (in response to Krishna)
    Re: Non-Broadcast Multi-Access (NBMA)

    Hi,

    the default encapsulation for serial interfaces is HDLC and so it has nothing to do with Frame-relay.

     

    Regards.

     

    Alain

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  • cadetalain 2,728 posts since
    Sep 18, 2008
    Currently Being Moderated
    14. Feb 28, 2013 4:17 AM (in response to Krishna)
    Re: Non-Broadcast Multi-Access (NBMA)

    Hi,

    1) HDLC is point-to-point so everyting is sent out the link.

    2) no it won't work, you'll have to do a back-to back frame-relay config:

    on R1:

    int s1/0

    ip address 172.16.1.1 255.255.255.252

    encapsulation frame-relay

    no keepalive    -----> disables LMI as you've got no switch in between

    frame-relay map ip 172.16.1.2 100  ---> which DLCI to use

    no sh

    on R2:

    int s1/0

    ip address 172.16.1.2 255.255.255.252

    encapsulation frame-relay

    no keepalive    -----> disables LMI as you've got no switch in between

    frame-relay map ip 172.16.1.1 100

    no sh

     

    You can also use a router as a Frame-Relay switch in between which is better to understand frame-relay

     

    Regards.

     

    Alain

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