nbma

[carl_townshend]

what is a non broadcast multiaccess network ?

[vijayasankar]

Hi,

NBMA is usually refered in Networking technologies like FR, X.25 and ATM.

and is often discussed with design of OSPF over Frame Relay.

NBMA - It simply means that the underlying layer 2 protocol doesn't have a native implementation to support broadcast capabilities.

Say for ex. Ethernet has native capabilities to support broadcast.

This means if a layer 3 broadcast packet needs to be sent over ethernet, the layer 2 destination address in the ethernet frame will be set to broadcast address ( all ones in the mac address). In ethernet any frame having the destination mac address as all ones means it is a broadcast, hence this frame will be delivered to all the members in that ethernet segment.

Such capabilities is not available in a FR /x.25 or ATM frame.

HTH

-VJ

[carl_townshend]

so does this mean you cant send broadcasts over this type of link ?

[ilya.varlashkin]

Besides point-to-multipoint FR, X.25 and ATM, another type of NMBA is multi-point GRE tunnel interface (mGRE).

In order to send broadcast and multicast traffic over NBMA networks some extra configuration is required. For example, in case of FR you use 'frame-relay map ip broadcast'. In case of mGRE there is NHRP to solve this problem.

[abhishek_nandavat]

Hi,

Check out this link for NBMA:

http://www.freepatentsonline.com/6047329.html

Hope this helps!

Regards,

AbhisheK

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