BGP Prefix Limit Configuration in Cisco, Juniper and Nokia - Interop

BGP Prefix Limit

Maximum Prefix-limit is used to control the BGP peer not to overload your BGP routing table and it helps to avoid the situation. let's explore how to configure in Cisco, Juniper, and Nokia router

Cisco Configuration

 !

router bgp 300

 neighbor 192.168.1.1

  address-family ipv4 unicast

   maximum-prefix <max-limit> <percentage> <Actions>

  !

 !

Juniper  Configuration

edit protocol
bgp {
        group nokia {
            neighbor 192.168.0.1 {
                family inet {
                    unicast {
                        prefix-limit {
                            maximum 1000;
                            teardown;
                        }
                    }

Nokia Configuration

/configure router bgp

            group "juniper"

                type external

                local-as 100

                neighbor 192.168.0.2

                    prefix-limit <family> <prefix-limit>

                    peer-as 200

                exit

   

BGP MD5 Configuration on Cisco - Juniper - Nokia Interop

 In this blog, I will explain the benefits of the MD5 concept and how to configure it on Cisco, Juniper, and Nokia Router

TCP-MD5

MD5 is used to protect the BGP session between the peers to form the secured session over the public Network. 

TCP MD5 option supports only one key for a connection. Further, it only supports the MD5 algorithm. The MD5 algorithm takes the “secret” from the key and the TCP segment for encryption and generates a message digest. This message digest is then copied to the MD5 digest field in the TCP segment and is sent to the receiving device.

Cisco XR

router bgp 300

 neighbor 192.168.1.1

  password encrypted 011D03104C0414042D4D4C

Juniper

edit protocols {                             

    bgp {

        group nokia {

            neighbor 192.168.0.1 {

                authentication-key "key"; ## SECRET-DATA

                }

      

Nokia

/configure router 

protocols {                             

    bgp {

     group "juniper"

                type external

                local-as 100

                neighbor 192.168.0.2

                    authentication-key "D8XsPtn4bCNLm" hash2

                    peer-as 200

                exit

Nokia 7750 SR BGP Next-Hop-Self (NHS) configuration

In our previous blog, we configured iBGP between Nokia SR Routers. PE01 received routes from CE via eBGP and advertised them to PE02.

Nokia Router (Alcatel-Lucent) BGP configuration Basic

Let's explore the output of PE02 for the prefix 10.10.10.5/32 advertised from CE01.

Prefix 10.10.10.5/32  is available in the BGP table of PE02

as per the below output, the route is not installed in the routing table of PE02. lets us explore the reason for not installing in its routing table of PE02.

    

From the above Output says that Invalid IGP for the next-hop advertised by the PE01 for the 

prefix 10.10.10.5.

By default when the route is advertised from ebgp it will change the next-hop to its own IP.

but in the case of iBGP, let's apply the policy to change the next-hop.

/configure router bgp group ibgp-internal next-hop-self 

After configuring the next-hop-self command on PE01, Now PE01 advertising its IP as net-hop for the 

prefix 10.1.5.5 and installing it in routing table.