Shared cache servers on an island's IXP

Thu Jan 18 17:24:32 UTC 2024

Jérôme Nicolle wrote on 18/01/2024 14:38:
> Those I'm nearly sure I could get, if I can pool caches amongst ISPs. 
> The current constraints are issues to any content provider, not just for 
> local ISPs.

two issues here: the smaller issue is that CDNs sometimes want their own 
routable IP address blocks, especially if they're connecting directly to 
the IXP, which usually means /24 in practice. It doesn't always happen, 
and sometimes the CDN is happy to use provider address space (i.e. IXP), 
or smaller address blocks. But it's something to note.

The bigger issue is: who pays the transit costs for the CDN's cache-fill 
requirements? CDNs typically won't pay for cache-fill for installations 
like this, and if one local ISP is pulling disproportionate quantities 
of data compared to other ISPs at the IXP, then this can cause problems 
unless there's an shared billing mechanism built in.

Nick