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Beginner

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Sandeep,

Can you please explain what is BGP peer groups and what is the benift of using this.

Regards

SN Gautam

Cisco Employee

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Satnarain

BGP peer group is a good concept which is very helpful in reducing the CPU processing for the BGP running device.You can group BGP neighbors who share the same outbound policies together in what is called a BGP peer group. Instead of configuring each neighbor with the same policy individually, a peer group allows you to group the policies which can be applied to individual peers thus making efficient update calculation along with simplified configuration.

Benifits of configuring BGP peer group:

============================

The major benefit you achieve when you specify a BGP peer group is that a BGP peer group reduces the amount of system resources (CPU and memory) necessary in an update generation. In addition, a BGP peer group also simplifies the BGP configuration. A BGP peer group reduces the load on system resources by allowing the routing table to be checked only once, and updates to be replicated to all peer group members instead of being done individually for each peer in the peer group. Based on the number of peer group members, the number of prefixes in the table, and the number of prefixes advertised, this can significantly reduce the load. It is recommended that you group together peers with identical outbound announcement policies.

Hope this answers your queries. Please feel free to contact in case you need any further clarification.

Thanks & Regards

Sandeep

Beginner

Re: Configuring and Troubleshooting Border Gateway Protocol (BGP)

When Ebgp & Ospf is configured on router and we have to ospf route should prefer rather than ebgp route???

Beginner

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Sandeep,

Can you please explain what is BGP peer groups and what is the benift of using this.

Regards

Highlighted
Cisco Employee

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Satnarain

I think by mistake you have posted the query twice. I have responded to your query please refer the above section/reply.

Thanks & Regards

Sandeep

Beginner

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Sandeep

Your posted reply is very helpful to my team

Thanks

SNG

Beginner

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Sandeep

Need to know what is the best possible way that RTA should reach network 160.10.0.0 directly via RTB rather taking the path to RTC because here in this router RTA will have the this route preferred via EBGP (Ad=20) as compared to EIGRP. Do we have any other option that changing the AD value to achieve this? Refer the below link for diagram


Thanks

Hanuman


Cisco Employee

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Hanuman

Considering your query and diagram, RTA and RTC are running EBGP, and RTB and RTC are running EBGP. RTA and RTB are running Eigrp.By definition, EBGP updates have a distance of 20 which is lower than the Eigrp (90) distances.

RTA will receive updates about 160.10.0.0 via two routing protocols: EBGP with a distance of 20 and EIGRP with a distance higher than 20 (=90).

On way to fulfil your requirement s to change EBGP's external distance or IGP's distance, but which is not recommended. So the solution to your problemis to Use BGP backdoor.

BGP backdoor makes the IGP route the preferred route.

Command to configure Backdoor

========================

The configured network is the network that we would like to reach via IGP. For BGP this network will be treated as a locally assigned network except it will not be advertised in BGP updates.

    RTA#

    router eigrp 10

    network 160.10.0.0

    router bgp 100

    neighbor 2.2.2.1 remote−as 300

    network 160.10.0.0 backdoor

Network 160.10.0.0 is treated as a local entry, but is not advertised as a normal network entry.

RTA learns 160.10.0.0 from RTB via EIGRP with distance 90, and also learns it from RTC via EBGP with distance 20. Normally EBGP is preferred, but because of the backdoor command EIGRP is preferred.

Hope it answers your query. Please feel free to contact in case you have any query or need any further clarification.

Thanks & Regards

Sandeep

Beginner

Configuring and Troubleshooting Border Gateway Protocol (BGP)

Hi Sandeep

Thanks for your given solution I implemented this solution and working fine

Thanks and Regards

Hanuman

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