Posts Tagged ‘bgp local preference’

Oct
20

In our R&S CCIE Mock Lab 2 there is a BGP task that relates to having a particular router prefer an iBGP route as the preferred path to exit its local AS over an eBGP learned path. This seems like a very simple task and it is if you are very thorough with your verification but it ends up being the most commonly missed task in this particular mock lab. Lets start by going over the task and the solution most commonly implemented by students.

In the lab R1, R2 and SW2 are in AS 300. R1 and R2 each have an eBGP peering session with R3. The task states that AS 300 should use the T1 link between R1 and R3 to reach paths originating in AS 54 (BB3). R3 (sub-AS 65003) appears as AS 100 but is actually in a confederation with R4 (sub-AS 65004) and R5 (sub-AS 65005). This doesn’t have any bearing on the task but needs to be mentioned for clarification when looking at the diagram and the output of the show commands. Below is the full task and the diagram (click the image to enlarge).
BGP Route Preference
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