[ih] Exterior Gateway Protocol

[tony.li at tony.li]

>  Back in the 1980s, the Loose Source Routing and Strict Source Routing were typically observed by routers, so we had a sandbox with which to play with these ideas.  It seemed a reasonable and practical idea to make use of Loose Source Routing in applications where Policy Routing was demanded.
>  Within a decade, of course, most any form of source routing was regarded with horror.


Worry not, it’s back. This time in the guise of SRv6.


>  Again, focusing on history, sometimes a technical idea (here, the binary intra-AS / inter-AS split, can allow an infrastructure to grow to become unstoppable and yet not be adequate for the additional growth it will need after becoming unstoppable.


As noted, it didn’t work out to be binary.  There are many ISPs out there using multiple ASes to segregate different regions/fiefdoms. Other people using BGP as an IGP in their enterprise, and many using BGP to route their leaf-spine data centers, with one AS number per router.

All permutations will be explored…

Tony