Scalable iBGP Design and Implementation Guidelines - BGP Design and Implementation - page 278

Figure 7-21 Persistent Convergence Oscillation with Improper IGP Metrics

AS 100

RR RR

5

R8

R1

15

Client

20 6

Client

R2

Client

R3 R4

10

10

MED: 10 10

MED: 5

MED: 6

AS 200 AS 300

R5 R6

172.16.0.0/16

AS 400

172.16.0.0/16

R7

The following steps describe the process that leads to the convergence loop:

Step 1 All three border routers in AS 100 announce 172.16.0.0/16 with next-
hop-self . The neighbor and path information is shown in Table 7-10.
Table 7-10 Neighbor and Path Information on Three Border Routers

Router BGP Next Hop AS_PATH MED

R2 R5 200 400 10

R3 R6 300 400 5

R4 R6 300 400 6