Load-Balancing

I posted about the home network in multiple other posts in past. I recent time I switched from Microtik SXT Lite 5 to Power Beam PBE-M5-400. This gave me a jump from 16dbi to 25dbi which gives much sharper beam. I also got a harness & climbed BTS myself (after getting permission from the manager) this time to switch gear. I think I can do a better job than wasting time in finding guys from local WISPs to do it. :)   Also, Essel Group launched Siti broadband in my home area and they are using DOCSIS. The network is overall fine though initially faced many outages due to fibre cuts here & there. As of now, the connection is reasonably stable. I am paying 860Rs/month ~ $14 for 10Mbps uncapped link which gives me 10Mbps down and 1.5Mbps up. From a price point, it’s an excellent connection to have for redundancy reasons. Now as the connection is stable enough to explore auto-failover. For last few months I took both primary links as well as backup links to the router in the form of tagged VLANs and used to push specific traffic based on source IP (device at home) or destination IP/port combination using policy based routing.  

An excellent presentation by James Quinn from Facebook on “Being Open How Facebook Got Its Edge” at NANOG68. YouTube link here and video is embedded in the post below.

Some key points mentioned by James:

1. BGP routing is inefficient as scale grows especially around distributing traffic. They can get a lot of traffic concentrated to a specific PoP apart from the fact that BGP best AS_PATH can simply be an inefficient low AS_PATH based path.
2. Facebook comes with a cool idea of “evolving beyond BGP with BGP” where they use BGP concepts to beat some of the BGP-related problems.
3. He also points to fact that IPv6 has much larger address space and huge summarization can result in egress problems for them. A single route announcement can just have almost entire network behind it!
4. Traffic management is based on local and a global controller. Local controller picks efficient routes, injects them via BGP and takes care of traffic balancing within a given PoP/city, balancing traffic across local circuits. On the other hand, Global PoP is based on DNS logic and helps in moving traffic across cities.

It’s wonderful to see that Facebook is solving the performance and load related challenges using fundamental blocks like BGP (local controller) and DNS (global controller). :)