Discussion

Within a group, you need to configure three things to set up the EBGP session:
1. Use the type external statement to define the session as an external one.
2. Set the AS number of the remote peer AS (here, 65505).
3. Specify the address of the neighboring border router (here, 10.0.31.1).
For EBGP sessions, use the peer router’s interface address. You can use the interface
address instead of the router’s lo0 address because, in most cases, the link between
ASs is a point-to-point WAN link. If this link goes down, the peer router is unreachable
anyway, so the remote AS would also be unreachable.
To establish the EBGP session, configure a similar EBGP group on the other border
router:
[edit routing-options]
aviva@RouterD# show
router-id 192.168.14.1;
autonomous-system 65505;
[edit protocols]
aviva@RouterD# show
bgp {
group session-to-AS65500 {
type external;
peer-as 65500;
neighbor 10.0.31.2;
}
}
Another useful bit of information to set for each neighbor is a text description of the
peering session:
[edit protocols bgp]
aviva@RouterF# set group session-to-AS65505 description "EBGP to Customer A"
This is especially useful to help identify peering sessions when many sessions are
configured on a single router.
After you have configured the two peer routers, check that they have established a
BGP connection:
aviva@RouterF> show bgp neighbor
Peer: 10.0.31.1+1778 AS 65505 Local: 10.0.31.2+179 AS 65500
Description: EBGP to Customer A
Type: External State: Established Flags:
Last State: OpenConfirm Last Event: RecvKeepAlive
Last Error: None
Options:
Holdtime: 90 Preference: 170
Number of flaps: 0
Peer ID: 192.168.14.1 Local ID: 192.168.16.1 Active Holdtime: 90
Keepalive Interval: 30 Peer index: 0
Local Interface: t1-0/0/3.0
NLRI advertised by peer: inet-unicast
424 | Chapter 13: BGP
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