BGP loop prevention mechanisms
For visitors or readers looking for information on BGP loop prevention, and does not want to read all the complete tutorial, i will point them to these parts of the tutorial.
For BGP loop prevention within an AS, or Ibgp loop prevention based on Split-horizon mechanisms, plz read the following pages :
- p29 to p31 of the tutorial(pdf) in download section
- or go here : A.5.b) Ibgp loop prevention: “split-horizon” mechanism
For BGP loop prevention between different ASs, or ISPs, which is a very important notion to understand when u are confronted to build a network with multihoming, redundancy and link failure options, plz read the following pages. As-path attribute allow ebgp loop prevention.
However the concept of BGP loop between ISPs or different ASs is very tricky since this is not something that you can experience in your own network. You will be more likely victim of it, particularly if your traffic engineering redundancy case has not been fully tested. I will even say that ebgp loop prevention is mainly related to peering agreements betweens ISPs.
This is deeply explained though the tutorial, but the four following sections are sufficient to make a clear outlook.
1)Presentation of the network implemented through the study-case
- p8 to p11 of the tutorial(pdf) in download section
- or go here : I.2) Overview of the study case: BGP tutorial , best practices and multihoming techniques on ISP proposing IP transit services.
and here : I.3) Bandwidth Planning and Provisioning for load-balancing features.
2) Peering agreement between the upstream/transit providers
- p16 to p17 of the tutorial(pdf) in download section
- or go here : A.2.b) Peering agreement between the upstream/transit providers
3) Ebgp loop prevention mechanism based on as-path attribute
- p27 to p28 of the tutorial(pdf) in download section
- or go here : A.5.a) Ebgp loop prevention mechanism based on as-path attribute
4) Observations and commentaries of the results and the redundancy scenarios.
- p74 to 84 of the tutorial(pdf) in download section
- or go here : C.1) Observations and commentaries of the results and the redundancy scenarios.
BGP search topics
I was looking on the stats of the blogs, it seems that some specific subjects are searched by readers. I will try to make specific posts on these topics, since the aim is to allow readers to find quickly the researched subject and not be obliged to run all the website or the tutorial of 110 pages.
Chapter B BGP tutorial on site
BGP tutorial can be downloaded(in pdf), but also read on site.
Ok, it took me a while to publish ChapterB.
Chapter B aims directly to the configuration of the study-case. To summarize, ChapterB targets the design directly and its configuration.
Ebgp and Ibgp configurations are described and deeply explained. Peering agreements and multihoming are enlightened in a practical way.
As a reminder, the study-case has for for goal to give a demonstration on how to use BGP and understand it in a world of interconnected ISPs. The contents describe practices and techniques about an ISP customer who:
- buys IP transit connectivity from different ISPs.
- needs to implement a load-balancing process.
- inserts redundancy and multihoming options for the Internet provision in case of link failure.
Do not worry, u will find more than a template or configuration, each command line, and choice of the structure is described in an exhaustive way. Many diagrams are also present in order to understand why and how the traffic engineering has been built.
The notions described :
- peering agreements
- BGP traffic engineering tools
- local preference
- bgp communities
- as-prepend
- Ebgp
- Ibgp
- network aggregation
- EBGP and IBGP (cisco) multihoming template
Thx for visit and need of reviews or critics
At least, the site was not updated since 3 weeks, lot of silly works issues and health troubles.
By the way i am seeing that the site got visitors, i am glad for that, and if people want to contribute with some articles or critics, it is welcomed.
BGP is a very specific topic on networking, i am trying to give through my tutorial a simple approach but also a practical example, which allow to work on it directly within an ISP.
Not an easy task, some readers will find the article nice, others too simple.
Well whatever it is, please send me critics by mail.
Thx a lot
Contents Chapter BGP tutorial on site.
BGP tutorial can be downloaded(in pdf), but also read on site.
Introduction chapter is published. It introduces the design of the network and its topology for the study case.
You will find diagrams on the BGP and Static design; the traffic engineering targeted configuration, and a listing of IP-addresses and interfaces used.
