Illustrated TCP/IP Illustrated TCP/IP
by Matthew G. Naugle
Wiley Computer Publishing, John Wiley & Sons, Inc.
ISBN: 0471196568   Pub Date: 11/01/98  

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Chapter 296
The Local-Group Database

The local-group database consists of three components:

Multicast group: A Class D IP address.
Attached network: The IP address of the attached network that contains the multicast group.
Age: The number of seconds since an IGMP Host Membership report has been seen.

Other routers find out about local-group members through the group-membership LSA. There is one LSA for each multicast group that has one or more entries in the local-group database.

The link-state database indicates which routers/transit networks have attached group members.

The Local-Group Database

•  Built in the DR and BDR.
•  Consists of three components:
•  A multicast group—a Class D address
•  Attached network—the IP address of the attached network that contains the multicast group
•  Age—the number of seconds since an IGMP Host Membership report has been seen
•  Flooded throughout the AS (or single area).
•  Assists in building the link-state database and the shortest-path tree.
•  Facilitates in the delivery of local multicast datagrams.


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