thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Routing & Switching · Advanced

Cluster List

An optional non-transitive BGP attribute listing the cluster IDs of route reflectors a route has passed through.

Definition

An RR prepends its cluster ID when reflecting a route and discards any route whose cluster list already contains its own ID, preventing loops among redundant reflectors. Shorter cluster list length is a late tie-breaker in best-path selection.

Example

bgp cluster-id 1.1.1.1

Exam tip

Redundant RRs sharing a cluster ID will not accept each other's reflected routes from that cluster.

Related terms