Examples: Configuring Route Reflection

This example shows how to configure a simple route reflector. The configuration shown in Figure 11 contains three routes: Router 1, which is the route reflector; Router 2, which is a client; and Router 3, which is a nonclient.

The routers have the following loopback addresses:

• Router 1—10.1.2.3
• Router 2—10.1.2.4
• Router 3—10.1.2.5

You must configure all routers to run a common IGP or to have static configuration, so that they learn each other’s loopback addresses.

Figure 11: Simple Route Reflector

Configure Router 1 to be a route reflector for Router 2 and a regular IBGP neighbor for Router 3:

Configure Router 2 to be an IBGP neighbor to Router 1 and announce 16.0.0.0/8 to Router 1. Configure route 16.0.0.0/8 as a static route on Router 2.

Configure Router 3 to be an IBGP neighbor to Router 1 and announce 15.0.0.0/8 to Router 1. Configure route 15.0.0.0/8 as a static route on Router 3.

The following is the output of the show route detail command for route 16.0.0.0/8 on Router 1 and Router 3. Note that Router 1 learns 16.0.0.0/8 from its client, Router 2, and reflects it to Router 3. On Router 3, the output of the show route commands include the cluster list and originator ID attributes, which are added by Router 1 when the route is reflected.

inet.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
16.0.0.0/8 (1 entry, 1 announced)
*BGP   Preference: 170/-101
Source: 10.1.2.4
Nexthop: 172.16.1.2 via fxp0.0, selected
State: <Active Int Ext>
Local AS: 65534        Peer AS: 65534
Age: 11:55        Metric2: 0
Task: BGP_65534.10.1.2.4+4327
Announcement bits (3): 2-KRT 3-BGP.0.0.0.0+179 4-BGP_Sync_Any
AS path: I
BGP next hop: 172.16.1.2
Localpref: 100
Router ID: 10.1.2.4

inet.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
16.0.0.0/8 (1 entry, 1 announced)
*BGP   Preference: 170/-101
Source: 10.1.2.3
Nexthop: 172.16.1.2 via fxp0.0, selected
State: <Active Int Ext>
Local AS: 65534        Peer AS: 65534
Age: 11:57      Metric2: 0
Task: BGP_65534.10.1.2.3+4619
Announcement bits (2): 2-KRT 4-BGP_Sync_Any
AS path: I <Originator>
Cluster list: 1.2.3.4
Originator ID: 10.1.2.4
BGP next hop: 172.16.1.2
Localpref: 100
Router ID: 10.1.2.3

The following is the output of the show route detail command for route 15.0.0.0/8 on router 1 and router 2. Similar to when routes are reflected from client peers to nonclient peers, router 1 reflects a route it learns from a regular IBGP neighbor to its client. Cluster list and Originator ID attributes are added during the reflection process.

inet.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
15.0.0.0/8 (1 entry, 1 announced)
*BGP   Preference: 170/-101
Source: 10.1.2.5
Nexthop: 172.16.1.2 via fxp0.0, selected
State: <Active Int Ext>
Local AS: 65534        Peer AS: 65534
Age: 11:14        Metric2: 0
Task: BGP_65534.10.1.2.5+179
Announcement bits (3): 2-KRT 3-BGP.0.0.0.0+179 4-BGP_Sync_Any
AS path: I
BGP next hop: 172.16.1.2
Localpref: 100
Router ID: 10.1.2.5

inet.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
15.0.0.0/8 (1 entry, 1 announced)
*BGP   Preference: 170/-101
Source: 10.1.2.3
Nexthop: 172.16.1.2 via fxp0.0, selected
State: <Active Int Ext>
Local AS: 65534        Peer AS: 65534
Age: 11:23        Metric2: 0
Task: BGP_65534.10.1.2.3+179
Announcement bits (2): 2-KRT 4-BGP_Sync_Any
AS path: I <Originator>
Cluster list: 1.2.3.4
Originator ID: 10.1.2.5
BGP next hop: 172.16.1.2
Localpref: 100
Router ID: 10.1.2.3

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