IP Telephony Cookbook by Saverio Niccolini, Jorg Ott, et al - HTML preview

E

D: sip:10,18,19

C: sip:10,18,19

A: sip:11..13,21

B: sip:14,15

B: h323:19

Figure 7.5 TRIP: Advertising gathered knowledge

When a LS collects a continuous range of telephone numbers (e.g., from 770 to 779), it can aggregate this information to a common prefix. In the example given in Figure 7.6, Node D

knows how to reach the numbers from sip:10 to sip:19. Since E is not on the path to one of these numbers, it withdraws the routes sent previously and adds a new route containing the prefix ‘1’.

Node C could have done the same for h323:10 to h323:19 when talking to A, but since C was configured not to put itself in the chain of next-hop servers (or simply because the feature is not supported), it does not aggregate that information.

A: sip:11,12,13,21

B: sip:14,15

B: sip:14,15