
Configuring IP Services
8-4
If alternate paths exist between different network segments, broadcasting loops
can occur. To prevent such loops, the router
1. Stamps the data portion of the IP packet with the IP address of the router from
which the packet was rebroadcast
2. Parses the IP addresses included in the data portion of the IP packet to
determine if the packet has already been rebroadcast by that router
In Figure 8-2, for example, Client C on the network connected to Router B wishes
to communicate with Server S, which is located on the network connected to
Router A.
1. The client issues a Name Query Request to NetBIOS on the host, specifying
the server application by its NetBIOS name. The IP service on the host
broadcasts the Name Query Request.
2. Router B receives the Name Query Request, determines that it is a broadcast
message, and rebroadcasts it out each of its NetBIOS interfaces (except for
the one on which it arrived).
3. Router A receives the broadcast Request and rebroadcasts to its local network.
4. The server on Router A receives the IP broadcast Request and recognizes its
own name.
Figure 8-2. Broadcasting a Name Query Request
c
s
Router C
c
s
Client
Server
Router A
Router B
Router D
Key
NetBiOS/IP Interface
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