Implement BGP in a scalable network

Horizontal isolation rules:

Routes learned through IBGP cannot be transmitted to other IGBP peers.

Route Reflector)

Route reflectors allow Routers configured as route reflectors to transmit Routes learned by IBGP to other IBGP peers to modify BGP horizontal isolation rules.

Advantages of Route reflectors:
With BGP Route reflectors configured, you no longer need an IBGP peer that is fully interconnected. Route reflectors are allowed to transmit IBGP routes to other IBGP peers. When the number of internal neighbor command statements is too large, I SP will adopt the routing reflector technology. Route reflectors reduce the number of BGP peers in the AS by allowing the primary routers to copy route updates to their route reflectors (this can reduce the number of t cp connections ).

The route reflectors do not affect the path through which IP data packets are transmitted. Only the path that publishes route information is affected. If the route reflectors are not correctly configured, a routing loop may be generated.

Terms of Route reflectors:
Route reflectors: A Router configured to allow it to advertise (or reflect) the route learned through IBGP to other IBGP peers.
Cluster: A combination of Route reflectors from other customers;
Customer: routers with some IBGP peering relationship between route reflectors and other routes
Non-customers: Other IBGP peers of customers who are not route reflectors;
Originator ID: it is an optional, non-pass BGP attribute, which is created by the route reflector. This property carries the ID of the route from the initiator inside the instinct;
Route reflectors cluster Table: the cluster ID sequence of the route report.

The originator ID, cluster ID, and cluster Table help prevent route loops in the route reflector configuration.

The customer who configures the router as a BGP Route reflector and the specified neighbor as it:
Neighbor ip-address route-reflector-client
Ip-address: the ip address of the BGP peer that will be identified as the customer
Bgpcluster-id cluster-id: configure the cluster ID
Show ip bgp neighbors: displays that the neighbor is a route reflector customer.

Policy Control and Prefix list)
The publishing list uses the access control list to specify which routes will be filtered.
Advantages of prefix list:
L significant performance improvement compared with access control lists in loading large lists and routing lookup
L support incremental modification;
L user-friendly command line interface
L greater flexibility

Configure the prefix list:
Ip prefix list-name [seq-value] [deny | permit] network/len [ge-value] [le-value]

Disable the number of the prefix list entries
No ip prefix-list sequence-number

Enable auto-generation of serial numbers again
Ip prefix-list sequence-number

View prefix list
Show ip prefix-list

Configure the neighbor connection weight
Neighbor {ip-address | peer-group-name} weight

Change the default local priority
Bgp default local-preference value

Article entry: csh responsible editor: csh