Networks ignoring prepends?

Tue Jan 23 02:53:09 UTC 2024

> > William Herrin <bill at herrin.us> wrote:
Until they tamper with it using localpref, BGP's default behavior with prepends does exactly the right thing, at least in my situation.

I feel your pain Bill, but from a slightly different angle.  For years the large CDNs have been disregarding prepends.  When a source AS disregards BGP best path selection rules, it sets off a chain reaction of silliness not attributable to the transit AS's.  At the terminus of that chain are destination / eyeball AS's now compelled to do undesirable things out of necessity such as:
  1) Advertise specifics towards select peers - i.e. inconsistent edge routing policy & littering global table
  2) Continuing to prepending a ridiculous amount anyway
Gotta wonder how things would be if everyone just abided by the rules.