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7.9.1 Establishing the Configuration Task
Before configuring BGP RRs, familiarize yourself with the applicable environment, complete
the pre-configuration tasks, and obtain the data required for the configuration. This will help
you complete the configuration task quickly and efficiently.
Applicable Environment
BGP uses the AS_Path attribute to prevent route loops, but it does not change the AS_Path
attribute of a route sent between IBGP peers within an AS. This may cause a route loop. To
prevent this problem, the BGP standard defines that a BGP device is prohibited from advertising
any route that received from another IBGP peer. Full-mesh connections then must be created
between IBGP peers to ensure the connectivity between them. If many IBGP peers exists, the
overhead will be large and the configuration workload will be heavy for establishing full-mesh
logical connections between switches. In addition, the network will be difficult to maintain.
Using BGP confederations or RRs can solve these problems. A BGP confederation consists of
several sub-ASs in an AS. Full-mesh logical connections need to be established and maintained
between IBGP peers in each sub-AS. To deploy RRs, you only need to configure the RR
functionality on switches and do not need to change configurations on other devices. In this
regard, deploying RRs is easier and more flexible than deploying confederations.
Pre-configuration Tasks
Before configuring a BGP RR, complete the following task:
l
Configuring Basic BGP Functions
Data Preparation
To configure a BGP RR, you need the following data.
No.
Data
1
Role of each switch (RR, client, or non-client)
2
(Optional) Cluster ID of the RR
7.9.2 Configuring a Route Reflector and Specifying Clients
Deploying an RR and clients in an address family allows IBGP peers to communicate without
having full-mesh logical connections established between them, reducing network configuration
and maintenance workload, and improving network performance.
Context
In an AS, one switch serves as an RR, and the other switches serve as clients. IBGP peer
relationships are set up between the RR and clients. The RR reflects routes between clients, and
BGP connections do not need to be established between the clients. A BGP device that is neither
an RR nor a client is called a non-client. Non-clients and the RR must establish full-mesh
connections with each other.
S6700 Series Ethernet Switches
Configuration Guide - IP Routing
7 BGP Configuration
Issue 01 (2012-03-15)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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