Configuring a BGP Router ID

The router ID should be configured first when you configure BGP. The router ID is a string similar to the IP address, and is the identifier of a BGP router in an AS. You should not change the router ID after completing the configuration. By default, the BGP router ID is not configured.

admin@XorPlus# set protocols bgp bgp-id 1.1.1.1
admin@XorPlus# commit
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring BGP Local-AS

The local AS (autonomous system) should be configured first when you configure BGP.
The AS_Path attribute records to all the AS's that a route passes through, from the source to the destination, following the order of vectors.

admin@XorPlus# set protocols bgp local-as 100
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring External BGP Peering

If the AS number of the specified peer is different from the local AS number during the configuration of BGP peers, an EBGP peer is configured. To establish point-to-point connections between peer autonomous systems, configure a BGP session on each interface of a point-to-point link. Generally, such sessions are made at network exit points with neighboring hosts outside the AS.

admin@XorPlus# set protocols bgp local-as 100
admin@XorPlus# set protocols bgp peer 192.168.49.1 as 200
admin@XorPlus# set protocols bgp peer 192.168.49.1 next-hop-self true
admin@XorPlus# set protocols bgp peer 192.168.49.1 local-ip 192.168.49.2
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring Internal BGP Peering

If the AS number of the specified peer is the same as the local AS number during the configuration of BGP peers, an IBGP peer is configured.

admin@XorPlus# set protocols bgp local-as 100
admin@XorPlus# set protocols bgp peer 192.168.49.1 as 100
admin@XorPlus# set protocols bgp peer 192.168.49.1 next-hop-self true
admin@XorPlus# set protocols bgp peer 192.168.49.1 local-ip 192.168.49.2
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring the BGP Local Preference

Internal BGP (IBGP) sessions use a metric called the local preference, which is carried in IBGP update packets in the path attribute LOCAL_PREF. When an autonomous system (AS) has multiple routes to another AS, the local preference indicates the degree of preference for one route over the other routes. The route with the highest local preference value is preferred.

admin@XorPlus# set policy policy-statement send-network term t1 from network4 172.168.200.0/24
admin@XorPlus# set policy policy-statement send-network term t1 from protocol bgp
admin@XorPlus# set policy policy-statement send-network term t1 then localpref 200
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# set protocols bgp peer 192.168.49.1 export send-network
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring BGP MED

The multi-exit discriminator (MED) helps determine the optimal route for the incoming traffic of an AS, and is similar to the metric used in IGP. When a BGP device obtains multiple routes to the same destination address but with different next hops from EBGP peers, the BGP device selects the route with the smallest MED value as the optimal route.

admin@XorPlus# set policy policy-statement send-network term t1 from network4 172.168.200.0/24
admin@XorPlus# set policy policy-statement send-network term t1 from protocol bgp
admin@XorPlus# set policy policy-statement send-network term t1 then med 200
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# set protocols bgp peer 192.168.49.1 export send-network
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring BGP Next Hop

When an Autonomous System Boundary Router (ASBR) forwards the route learned from an EBGP peer to an IBGP peer, the ASBR, by default, does not change the next hop of the route. When the IBGP peer receives this route, it finds the next hop unreachable, sets the route to inactive, and does not use this route to guide traffic forwarding.

To enable the IBGP peer to use this route to guide traffic forwarding, configure the ASBR to set its IP address as the next hop of the route when the ASBR forwards this route to the IBGP peer. After the IBGP peer receives this route from the ASBR, it finds the next hop of the route reachable, sets the route to active, and uses this route to guide traffic forwarding. 

When a BGP route changes, BGP needs to iterate the indirect next hop of the route again. If no restriction is imposed on the iterated route, BGP may iterate the next hop to an incorrect forwarding path, causing traffic loss. Configure routing policy-based route iteration to prevent traffic loss.

admin@XorPlus# set protocols bgp local-as 100
admin@XorPlus# set protocols bgp peer 192.168.49.1 as 100
admin@XorPlus# set protocols bgp peer 192.168.49.1 next-hop-self true
admin@XorPlus# set protocols bgp peer 192.168.49.1 local-ip 192.168.49.2
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring BGP Route Reflectors

To ensure the connectivity between IBGP peers within an AS, you need to establish full-mesh connections between the IBGP peers. When there are many IBGP peers, it is costly to establish a fully meshed network. A route reflector (RR) can solve this problem.

A cluster ID can help prevent routing loops between multiple RRs within a cluster, and between clusters. When a cluster has multiple RRs, the same cluster ID must be configured for all RRs within the cluster.

If full-mesh IBGP connections are established between clients of multiple RRs, route reflection between clients is not required and wastes bandwidth resources. In this case, prohibit route reflection between clients to reduce the network burden.

Within an AS, an RR transmits routing information and forwards traffic. When an RR connects to a large number of clients and non-clients, many CPU resources are consumed if the RR transmits routing information and forwards traffic simultaneously. This also reduces route transmission efficiency. To improve route transmission efficiency, prohibit BGP from adding preferred routes to IP routing tables on the RR, enabling the RR to only transmit routing information.

admin@XorPlus# set protocols bgp local-as 100
admin@XorPlus# set protocols bgp peer 192.168.49.1 as 100
admin@XorPlus# set protocols bgp peer 192.168.49.1 next-hop-self true
admin@XorPlus# set protocols bgp peer 192.168.49.1 local-ip 192.168.49.2
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#
admin@XorPlus# set protocols bgp route-reflector cluster-id 16.16.16.16
admin@XorPlus# set protocols bgp route-reflector disable false
admin@XorPlus# set protocols bgp peer 192.168.49.1 client true
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring BGP Confederations

A confederation divides an AS into sub-AS's, which establish EBGP connections. Within each sub-AS, IBGP peers establish full-mesh connections or have an RR configured. On a large BGP network, configuring a confederation can reduce the number of IBGP connections, simplify routing policy management, and improve route advertisement efficiency.

admin@XorPlus# set protocols bgp local-as 65533
admin@XorPlus# set protocols bgp peer 192.168.49.1 as 65533
admin@XorPlus# set protocols bgp peer 192.168.49.1 next-hop-self true
admin@XorPlus# set protocols bgp peer 192.168.49.1 local-ip 192.168.49.2
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#
admin@XorPlus# set protocols bgp confederation identifier 2000
admin@XorPlus# set protocols bgp confederation disable false
admin@XorPlus# set protocols bgp peer 192.168.49.1 confederation-member true
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Configuring the BGP Connect Timer

Hold timers can be configured for all peers. The proper maximum interval at which 'keep alive' messages are sent is one third the hold time.

admin@XorPlus# set protocols bgp peer 192.168.49.1 holdtime 30
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring MD5 Authentication for TCP Connections

Configure Message Digest5 (MD5) authentication on a TCP connection between two BGP peers. The two peers must have the same configured password to establish TCP connections.

admin@XorPlus# set protocols bgp peer 192.168.11.10 md5-password pica8
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring EBGP Fast-External-Fallover

This feature allows BGP to immediately respond to a fault on an interface, and delete the direct EBGP sessions on the interface without waiting for the hold timer to expire. It implements rapid BGP network convergence. By default, EBGP fast-external-fallover is disabled.

admin@XorPlus# set protocols bgp fast-external-fallover disable false
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

Configuring BGP Route Summarization

BGP supports both automatic and manual route summarization. Manual route summarization takes precedence over automatic.

Configure automatic route summarization as follows:

admin@XorPlus# set protocols bgp auto-summary true
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus# 

BGP auto-summary true summarizes the routes exported by BGP.

To configure manual route summarization:

admin@XorPlus# set protocols bgp aggregate network4 192.168.1.0/24 suppress-detail true
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Configuring BGP to Advertise Default Routes to Peers

The BGP device can be configured to send only a default route, with the local address as the next hop address, to its peer, regardless of whether there are default routes in the local routing table.

admin@XorPlus# set protocols bgp peer 192.168.11.10 default-route-advertise 
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Configuring BGP to Remove Private AS Numbers

Private autonomous system (AS) numbers that range from 64512 to 65535 are used to conserve globally unique AS numbers. BGP can remove private AS numbers from updates to a peer.

admin@XorPlus# set protocols bgp peer 192.168.11.10 public-as-only
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Configuring BGP AS Loop

Repeated local AS numbers are allowed in routes. In the default setting, however, repeated local AS numbers are not allowed.

admin@XorPlus# set protocols bgp peer 192.168.11.10 allow-as-loop true
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

Configuring BGP Load Balancing

If multiple paths to a destination exist, you can configure load balancing over such paths to improve link utilization.

Enable BGP load balancing:

admin@XorPlus# set protocols bgp multipath disable false
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#

BGP will not load balance across multiple paths by default. This is acceptable if you are multi-homed to a single AS, but if multi-homed to different AS path, you cannot load balance across theoretically equal paths.

Enter the BGP multipath path-relax command:

admin@XorPlus# set protocols bgp multipath path-relax true
admin@XorPlus# commit 
Waiting for merging configuration.
Commit OK.
Save done.
admin@XorPlus#