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Part 5 - Wrap Up (10.06. - 14.06.2024)

This week, there is time to finish tasks you had problems with during the past weeks and tweak the performance of your network.

Task (Question 2.5; optional)

Improve performance with BGP

In this question, you will configure your BGP policies to improve performance. The connection to one of your providers and to one of your customers has a noticeably higher delay than the other connections to your neighbors.

First, it is time to be a detective. Use the tools you have learned so far to discover which links have a higher delay. Once you have discovered these links, you need to optimize your BGP policies for both outgoing and incoming traffic.

How traffic leaves your network is determined by which incoming advertisements you select. Thus, to optimize outgoing traffic, configure BGP to prefer advertisements from the customer/provider with low delay.

How traffic enters your network is determined by the advertisements you send to your neighbors. Thus, to optimize incoming traffic, configure BGP s.t. reaching you via the high delay provider/customer is less attractive to other ASes. There are a couple of important things to consider:

  • Because of business relationships, your high-delay provider will always prefer sending traffic toward you directly. You must uphold the business relationships, so you cannot avoid this.
  • However, you can impact how other ASes reach you, and you can make it less attractive for them to reach you via the high-delay provider.

Hint:

Remember that attributes like local-pref only apply to your own AS and do not propagate to others. An attribute that does propagate to other ASes is the as-path, and BGP prefers the shortest path to the destination.

Important note

Importantly, you must not deny any advertisements to solve this task. That is, you should neither deny incoming advertisements nor block outgoing advertisements. The customer and provider with high delay should always remain available as backups for you (thus, you must not deny their advertisements), and they must be able to reach you directly (thus, you must not block advertisements towards them).

Additional Resources

You want to become an expert on BGP? Then the following video is for you:

page version 1.0 - last edited May 5th, 2024