Principles of Communications Week 4 L6/7 25&27 Oct, 2022 - BGP Abstraction + Multicast

 This week, we finished up looking at BGP by covering:

1. the stable paths abstraction - what does path vector+policy do, algorithmically?
2. real world dynamics and engineering for stability - the latter performance challenges show that the information hiding goals of inter-domain routing have not really been achieved very thoroughly! So intra-domain dynamics get exported to the world, because of hot potato and MEDs.

As well as this, BGP requires a lot of external machinery for specifying policy, and for guarding against misinformation (by definition, harder to do with a system which has a goal of information hiding).

Then we looked at Internet Multicast - this also has some interesting challenges, that have prevented wide spread adoption:

1. potential use for leveraging DDoS attacks
2. lack of a policy/interdomain/business model (who causes down stream traffic?)

In addition, multicast created headaches for high speed switch/router hardware designers

General lesson here is that global scale systems entail complex, multi-factor considerations, and don't believe everything out there running the world is actually based on completely sound design. Nevertheless, it has application in special cases/limited domains, such as backbones for TV distribution, and more especially, data center networks.

----admin:

Aside: just to support this, the university information service video recording system failed to capture audio&slides for the 20.10.22 lecture but luckily, last year's recordings are still available, and roughly from same dates (2021 recordings) e.g. 2021-10-19 2021-10-21 2021-10-26 

Apologies for that!