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Figure 40: Backdoor Route

You can modify this behavior by issuing the network backdoor command on router

NY:

host1(config)#router bgp 300

host1(config-router)#neighbor 10.4.4.1 remote-as 400

host1(config-router)#network 172.19.0.0 backdoor

Unlike the typical network command, network backdoor does not cause the BGP

speaker to advertise the specified prefix. Instead, it sets the administrative distance

for the EBGP path to that prefix to the same value as a route learned by means of

IBGP. That is, the EBGP administrative distance is changed from the highly preferred

value of 20 to the highly unpreferred value of 200. In Figure 40 on page 140, this

change in value results in the backdoor OSPF being more preferred as a way to reach

prefix 172.19.0.0/16.

network backdoor

■ Use to cause a backdoor IGP route to be preferred over an EBGP route to the

same prefix by setting the administrative distance of the EBGP route to that of

an IBGP route, 200.

■ Issuing this command does not cause the BGP speaker to advertise the specified

route.

■ This command takes effect immediately.

■ Example

host1(config-router)#network 10.53.42.0 backdoor

■ Use the no version to restore the default distance to the EBGP route, 20.

■ See network.

Setting the Maximum Number of Equal-Cost Multipaths

You can use the maximum-paths command to specify the number of equal-cost

paths to the same destination that BGP can submit to the IP routing table.

140 ■ Interactions Between BGP and IGPs

JUNOSe 11.1.x BGP and MPLS Configuration Guide

Juniper BGP - CONFIGURATION GUIDE V 11.1.X User Manual

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