ABGP (Advanced Border Gateway Protocol Configuration)

In this course, we expand upon the basics of the Border Gateway Protocol which you were introduced to in Cisco BSCI. We perform protocol analysis on how and why BGP form neighbor relationships and understand the various states of this relationship.

You learn about advanced configuration functions of the Border Gateway Protocol such as synchronization, dampening, and peer groups. We will discuss design choice such as fully meshed verses partially meshed and the ramifications of redistribution with the Border Gateway Protocol. We will look at and perform labs on solutions for excess peering by using BGP Confederation and/or BGP Route Reflectors.

This course also ensure that you have a through understanding of how BGP selects a pathway to be submitted to the IP routing table. Once this understanding is achieved, we will discuss and experiment with path manipulation to include labs in summarization using prefix list, prepend, local preference, and communities.

We will have BGP select routes using complex route maps, which were introduced to you in BSCN, which will contain regular expressions and access lists that allow us to manipulate the Autonomous System Path string.

Classroom and Virtual Classroom e-Learning Outline

Initial configuration of the routers in your pod to include a default route to reach the other Autonomous Systems in the classroom.

Basic BGP Multi-homing setup with two eBGP neighbors. Observe and troubleshoot the results.

Configure the BGP router ID by using loopback interfaces and the BGP router-id command. Configure BGP to redistribute directly connected networks and to use a specific source IP address for all updates. Observe and troubleshoot the results.

Perform the three choices internal routers have for leaving an autonomous system. Configure choice 1 to run BGP on the edge rotuers and pass a default route into the autonomous system. Configure choice 2 by redistributing BGP to your autonomous system's IGRP. Configure choice 3 by enabling BGP on all routers in your AS and disabling BGP synchronization. Observe the results for each choice and troubleshoot.

Perform BGP summarization with the aggregate address command Typical Internet level problems with summarization will be encountered and solutions, such as no auto-summary will need to be worked out. Examination of the results of the lab will also be performed

Announce unique CIDR blocks for your autonomous system to each external neighbor using a complex prefix list.

Document and understand how BGP selects a pathway. Manipulate the general flow of data by changing the default setting for Local Preference.

A 10 part exercise which uses screen captures of actual BGP pathways on the Internet to decide on why BGP selected a particular pathway over another.

Using basic regular expressions, figure out which strings will match based on the logic of the regular expression

Build regular expressions which are common to BGP to answer typical real world problems for path selection

Enable BGP dampening and observe how external routes are affected. Learn how to clear the dampen routes and the flap statistics.

Using regular expressions and a BGP filter list, create policy based route expressions which choose a specific pathway to reach other Autonomous Systems.

Using a route map, change the origin code from incomplete to IGP when advertising to eBGP neighbors.

Create a route map using the prepend options to affect how packets enter your Autonomous System.

Create a route map that advertises selected Local Preferences to your iBGP neighbors so that they may choose the appropriate pathway to exit their Autonomous System. Create another route map using weight as the selection criteria for determining how packets exit your autonomous system.

Create a route map to influence how other Autonomous Systems reach the networks owned by your AS by advertising different multiple exit discriminators to your eBGP neighbors from your border routers.

Perform Summarization using route maps, community strings, and prefix lists so that the summarized routes are passed to neighboring Autonomous Systems but the more specific routes are flag to be filtered at the edge of the next Autonomous System.

Convert your fully meshed iBGP neighbors into a route reflector cluster with a single route reflectors and three route reflector clients.

Merge your autonomous system with a neighboring autonomous system by using a BGP confederation. Examine the results of this merger by examining the affects and advertisements that the confederation creates.

Self-Paced e-Learning Details

ECRC-Title 6: BGP - 281156