NBMA

liven

this is means:

none
broadcast
multi
access

correct?

Can others please give me a one or two sentence example, something that I can put in my daily review notes (stuff that I need to know off the top of my head) describing NBMA

thanks

techster79

NBMA=Non-Broadcast Multi-Access

Compared to Ethernet(Broadcast Multi-Access), NBMA is the normal type of frame-relay behavior. You have more than just a point-to-point link, you can be directly connected to multiple sites with frame-relay. By default, broadcasts are disabled. It is also a type of OSPF that can be used.

NBMA
- NBMA (non-broadcast multiple access) is one of four network types in the OSPF (Open Shortest Path First) communications protocol. NBMA is used to accurately model X.25 and frame relay environments in multiple-access networks where there are no intrinsic broadcast and multicast capabilities. The other OSPF network types are: broadcast, point-to-point, and point-to-multipoint. In an NBMA configuration, OSPF sends HELLO packets (packets sent periodically to establish and confirm neighbor relationships between routers) to each router one at a time rather than multicasting them. The HELLO timer (which tells the router how often to send HELLO packets) is extended from 10 to 30 seconds and the dead router timer (which tells the router how long to wait before it decides that a neighboring router is not functioning) is extended from 40 to 120 seconds.

khristov

The most important thing about non-broadcast network type is that it is assumed it does not support multicast feature on the interface that it is set. The lack of this capability assumes that neighbors cannot be automatically discovered and must be configured using the "neighbor" command under the ospf router process on at least one side of the connection.
The forwarding address is not changed when updates are sent in the same area just like the broadcast network type. It is just multipoint connection like ethernet (except it does not support boradcast/multicast). In network topology point of view it is just like any-to-any connectivity, just like ehternet.