Juniper JUNOSE 11.2.X BGP AND MPLS, Configuration Manual

Page: 152 / 742

host4(config-router)# network 192.168.204.0 mask 255.255.252.0
host4(config-router)# redistribute isis
Consider how route 172.21.10.0/23 is passed along to the routers in Figure 33 on page 115:
1.
IS-IS injects route 172.21.10.0/23 from router Chicago into BGP on router LA. BGP
sets the origin attribute to Incomplete (because it is a redistributed route) to indicate
how BGP originally became aware of the route.
2.
Router Boston learns about route 172.21.10.0/23 by means of EBGP from router LA.
3.
Router NY learns about route 172.21.10.0/23 by means of IBGP from router Boston.
The value of the origin attribute for a given route remains the same, regardless of where
you examine it. Table 20 on page 116 shows this for all the routes known to routers NY
and LA.
Table 20: Origin and AS Path for Routes Viewed on Different Routers
AS Path Origin Router Route
300 IGP Albany 192.168.204.0/22
300 IGP Boston 192.168.204.0/22
300 IGP NY 192.168.204.0/22
empty IGP LA 192.168.204.0/22
300 Incomplete Albany 172.21.10.0/23
300 Incomplete Boston 172.21.10.0/23
300 Incomplete NY 172.21.10.0/23
empty Incomplete LA 172.21.10.0/23
empty IGP Albany 172.28.8.0/21
empty IGP Boston 172.28.8.0/21
empty IGP NY 172.28.8.0/21
100 IGP LA 172.28.8.0/21
empty Incomplete Albany 172.31.125.100
empty Incomplete Boston 172.31.125.100
empty Incomplete NY 172.31.125.100
100 Incomplete LA 172.31.125.100
Copyright © 2010, Juniper Networks, Inc. 116
JunosE 11.2.x BGP and MPLS Configuration Guide