Scalable iBGP Design and Implementation Guidelines - BGP Design and Implementation - page 300

Table 7-33 shows the current BGP RIB on R8. Step 6

Table 7-33 BGP Paths on R8

Path BGP Next Hop AS_PATH MED IGP Metric

1 * R3 (65000) 300 400 5 25

Table 7-34 shows the new BGP RIB on R1. Path 1 is the best path
because it has a lower IGP metric. R1 updates its neighbors with the new
best path.

Step 7

Table 7-34 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

The current BGP RIB on R8 is shown in Table 7-35. Next, R8 updates
R4 with the new path.

Step 8

Table 7-35 BGP Paths on R8

Path BGP Next Hop AS_PATH MED IGP Metric

1 * R2 65000 200 400 10 20

With the new update from R8, the BGP RIB on R4 is shown in Table 7-36.
Path 2 is best because it is learned from an external peer. Next, R4 sends
the update to R8.

Step 9

Table 7-36 BGP Paths on R4

Path BGP Next Hop AS_PATH MED IGP Metric

1 R2 65000 200 400 10 26

2 * R6 300 400 6 10

Step 10 Table 7-37 shows the updated BGP RIB on R8. Path 1 is best because it
has a lower IGP metric. Next, R8 sends updates to its neighbors.

Table 7-37 BGP Paths on R8

Path BGP Next Hop AS_PATH MED IGP Metric

1 * R4 300 400 6 6

2 R2 65000 200 400 10 20