Search results for: bgp policies
BGP Policies (Part 5)
At the most basic level, there are only three BGP policies: pushing traffic through a specific exit point; pulling traffic through a specific entry point; preventing a remote AS (more than one AS hop away) from transiting your AS to reach a specific destination. In this series I’m going to discuss different reasons for these kinds of policies, and different ways to implement them in interdomain BGP.
In this post I’m going to cover AS Path Prepending from the perspective of AS65001 in the following network—
Read MoreBGP Policies (Part 4)
At the most basic level, there are only three BGP policies: pushing traffic through a specific exit point; pulling traffic through a specific entry point; preventing a remote AS (more than one AS hop away) from transiting your AS to reach a specific destination. In this series I’m going to discuss different reasons for these kinds of policies, and different ways to implement them in interdomain BGP.
In this post, I’ll cover the first of a few ways to give surrounding autonomous systems a hint about where traffic should enter a network. Note this is one of the most vexing problems in BGP policy, so there will be a lot of notes across the next several posts about why some solutions don’t work all that well, or when they will and won’t work.
There are at least three reasons an operator may want to control the point at which traffic enters their network, including:
Read MoreBGP Policies (Part 3)
Assume AS65001 is some form of content provider, which means it offers some service such as bare metal compute, cloud services, search engines, social media, etc. Customers from AS65006 are connecting to its servers, located on the 100::/64 network, which generates a large amount of traffic returning to the customers. From the perspective of AS hops, it appears the path from AS65001 to AS65006 is the same length—if this is true, AS65001 does not have any reason to choose one path or another (given there is no measurable performance difference, as in the cases described above from AS65006’s perspective). However, the AS hop count does not accurately describe the geographic distances involved…
Read MoreBGP Policies (Part 2)
At the most basic level, there are only three BGP policies: pushing traffic through a specific exit point; pulling traffic through a specific entry point; preventing a remote AS (more than one AS hop away) from transiting your AS to reach a specific destination. In this series I’m going to discuss different reasons for these kinds of policies, and different ways to implement them in interdomain BGP.
There are many reasons an operator might want to select which neighboring AS through which to send traffic towards a given reachable destination (for instance, 100::/64). Each of these examples assumes the AS in question has learned multiple paths towards 100::/64, one from each peer, and must choose one of the two available paths to forward along. This post wil consider selecting an exit point from the perspective of two more autonomous systems.
Read MoreBGP Policies (part 1)
At the most basic level, there are only three BGP policies: pushing traffic through a specific exit point; pulling traffic through a specific entry point; preventing a remote AS (more than one AS hop away) from transiting your AS to reach a specific destination. In this series I’m going to discuss different reasons for these kinds of policies, and different ways to implement them in interdomain BGP.
Read MoreUpcoming BGP Policy Course
This coming Friday I’m teaching a course in BGP policy over at Safari Books Online. It’s three hours of straight-up BGP policy goodness. From the description:
Read MoreThis course begins by simplifying the entire BGP policy space into three basic kinds of policies that operators implement using BGP—selecting the outbound path, selecting the inbound path, and “do not transit.” A use case is given for each of these three kinds, or classes, of policies from the perspective of a transit provider, and another from the perspective of a nontransit operator connected to the edge of the ‘net.
Upcoming Training: BGP Policy
On July 21st I’ll be teaching BGP Policy over at Safari Books Online. From the description:
Read MoreThis course begins by simplifying the entire BGP policy space into three basic kinds of policies that operators implement using BGP—selecting the outbound path, selecting the inbound path, and “do not transit.” A use case is given for each of these three kinds, or classes, of policies from the perspective of a transit provider, and another from the perspective of a nontransit operator connected to the edge of the ‘net. With this background in place, the course will then explore each of the many ways these classes of policy may be implemented using local preference, AS Path prepending, various communities, AS Path poisoning, and other techniques. Positive and negative aspects of each implementation path will be considered.