Implementation of BGP Policy Routing

* BGP is designed to process a large number of Route entries.
Control the bandwidth traffic in a certain transmission direction.
1. Controllable attributes:
· Local priority:
It is valid for outbound traffic.
Relatively speaking, it is a priority.
· MED multi-exit identification:
Injected by external EBGP, It is set by the Administrator outside of AS to affect this.
To effectively control the traffic that leaves me.
· Weight
2. Control through route ing
The routing ing chart is used to control route updates in BGP.
Routing entry Input and Output policies are usually defined using a routing ing diagram.
Key points:
1. Multiple Route Map instances are sequentially executed on the vro.
2. If no matching is found in the route ing diagram, data packets are forwarded through the normal route channel;
3. If you want to discard a packet that does not match the specified standard, you can use the set statement to forward the packet to interface null0. You can use this statement as the last entry of Route ing.
For example, apply a route ing diagram to a BGP neighbor router.
Access-list 1 permit 1.1.1.0 0.0.255
Access-list 2 permit 1.2.1.0 0.0.255
Route-map mymap permit 10 // map Name mymap, Action permit map number 10
Match ip address 1 // match ACL 1
Set weight 300 // The route weight from the 1.1.1.0 CIDR block is 300
Route-map mymap permit 20
Match ip address 2 // match Access Control List 2
Set weight 100 // The route weight from the 1.2.1.0 network segment is 100
Router bgp 65038
Neighbor 172.16.20.2 remote-as 65011
Neighbor 172.16.20.2 remote-map out // apply the route map to the out direction.

Note: When configuring BGP, if the neighbor address is the loopback port address, you must first declare it.
If the source address of the update packet is not a neighbor address, the packet will be discarded.
Neighbor 2.2.2.2 remote-as 65001
Neighbor 3.3.3.3 remote-as 65001
Neighbor 2.2.2.2 remote-as 65001 update-source loopback0
Neighbor 2.2.2.2 remote-as 65001 update-source loopback0

Iii. BGP policy routing configuration
1. Local priority configuration-transmitted only in this
* (In bgp process mode)
(Config-router) # bgp default local-preference <0-4294967295> // The default value is 100.
* Configure the local priority using the route ing diagram.
Set local-preference 400
2. Configure the weight-private attribute, which can be viewed through show run.
* (In bgp process mode)
(Config-router) # neighbor 202.0.0.1 weight <0-65535>
* Configure the route map
Sets weight 200
3. Configure the MED value (boot entry)
* (In bgp process mode)
(Config-router) # default-metric <1-4294967295>
* Configure the route map
Set metric 50

 

PBR
· You can select to modify the next hop address and Mark data packets to provide different network services.
· PBR is generally used to modify the next hop address based on the source address.
· Recommended implementation method: PBR marks ip precedence for outgoing ip packets, which facilitates the implementation of QoS policies.
· Generally, PBR is configured through route ing.

From: 151 wqooo BLOG