BGP – as-path-prepend

1. Intro You can prepend one or more autonomous system (AS) numbers at the beginning of an AS path. The AS numbers are added at the beginning of the path after the actual AS number from which the route originates has been added to the path. Prepending an AS path makes a shorter AS path […]

3 mins read

BGP – loops

1. Intro When configured, loops will allow the local device’s AS number to be in the received AS paths, and specify the number of times detection of the local device’s AS number in the AS_PATH attribute causes the route to be discarded. There are 2 ways of configuring loops: As we can see, we can […]

8 mins read

BGP – as-override

1. Intro Compare the AS path of an route with the AS number of the BGP peer in the group, and replace all occurrences of the peer AS number in the AS path with its own AS number before re-advertising the route to the peer. This is essentially an alternate solution to the advertise-peer-as and […]

4 mins read

BGP – advertise-peer-as

1. The default In the Juniper documentation we have the following statement: by default, Junos OS does not advertise the routes learned from one EBGP peer back to any EBGP peers that are in the same AS as the originating peer. Let’s explore this feature and put it to the test. The text book scenario for […]

8 mins read