Scalable iBGP Design and Implementation Guidelines - BGP Design and Implementation - page 281

Figure 7-23 Prefix Propagation in Steps 5 and 6

R1 R8

RR RR

Withdraw

R2 R3 R4

Client Client Client

Step 5

Table 7-16 shows the current BGP RIB on R8. Step 6

Table 7-16 BGP Paths on R8

Path BGP Next Hop AS_PATH MED IGP Metric

1 *

R3 300 400 5 25

Table 7-17 shows the new BGP RIB on R1. Path 1 is the best path
because it has a lower IGP metric. Now R1 updates its neighbors with the
new best path, as shown in Figure 7-24. Because R2 is the next hop, R1
sends a withdrawal message.

Step 7

Table 7-17 BGP Paths on R1

Path BGP Next Hop AS_PATH MED IGP Metric

1 * R2 200 400 10 15

2 R3 300 400 5 20