User's Manual
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Compare MED of routes from different AS.
For more related information about the configuration of the attributes of several IP route selection protocols,
please refer to“The configuration of attributes of IP routing which are independent from the protocol”.
61.3 Configure basic BGP features tast
61.3.1 Configuring Basic BGP Features
1. Activate the route selection of BGP
In order to activate BGP route selection, use the following commands under global configuration mode to
activate BGP route selection:
Command Purpose
router bgp autonomous-system
Under router configuration mode, activate BGP
route selection process.
network
network-number/masklen [
route-map
route-map-name]
Tag the network as local autonomous system
and add it to the BGP list.
Notes:
For exterior gateway routing protocol, the using of configuration command “network ” to configure
an IP network canand to only control which networks will be informed. This is opposite to interior
gateway protocol (IGP), such as RIP, it is using command “network” to decide where to send the
update.
Command “network” is used to import IGP routes to BGP routing table. Router resource, such as
configured RAM, decides the upper limit of the usable command “network”. As a choice, you can
use command “redistribute” to achieve the same effect.
2. Configure BGP neighbour
To configure BGP neighbour is to establish the peer to exchange routing information. BGP neighbour ought to
be configured in order to exchange routing information with the outer world.
BGP supports two kinds of neighbours: internal neighbour (IBGP) and external neighbour (EBGP). Internal
neighbours are in the same AS; external neighbours are in different ASs. Normally, external neighbours are
adjacent to each other and share the same sub-network. But internal neighbours can be at any place in the
same AS.
Use configuration command “Neighbor” to configure BGP neighbour:
Command Purpose
neighbor
{ip-address | peer-group-name}
remote-as
number
Designate a BGP neighbour.
For example about the configuration of the BGP neighbor, please refer to the section in the bottom of this
chapter “an example of the configuration of the BGP neighbor”.
3. Configure BGP soft reconfiguration
Generally speaking, BGP neighbors only exchange all routes when the connections are established, after that,
they only exchange update routes. So if the configured routing policy gently changes, in order to apply it on
the received routes, it is necessary to clear BGP session. The clearing of BGP session will cause the
invalidation of cache and will exert great influence on the operation of the network. Soft reconfiguration function
enables the configuration and activation of policy without clearing BGP session. So, we recommend you to