[AusNOG] Not quite routing issue

[Michael J. Carmody]

Hey All,

With the recent allotment of another APNIC subnet to our company, we have been beating our head against an issue which has us stumped.

In short a client on a layer-2 service cannot reach Facebook, Seek, ADP Payroll portal and a bunch of other websites intermittently, but more often not, than can...

When we move them to our original  subnet range (same router, same layer 2 service, same client CPE) all is well.

We original suspected a routing issue, but pings/traceroutes work. Then we expected a MSS/MTU issue, but clamping all the way down to 1300 made no difference.

We then got weird and noticed we could get a response from the loadbalancer/CDN/proxy of facebook, asking for a nonsense URL, but if we asked for a valid URL we get no reply.

So we seem to have an issue affecting Facebook, seek.com.au and ADP payroll, that is not routing related (can ping/traceroute without an issue), not MTU related, (can clamp up and down without any affect), but somehow related to the IP range of CDN fronted services?

103.20.20.x/24 works for us and all our clients.
103.232.216.x/23 seems to work mostly with sporadic sites not loading.

Same router, same upstream peer, same everything else...

Can someone point out where our stupidity lies? We are very stumped here.

-Michael Carmody
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