On Thursday, 22 November, 2018 05:30, "William Herrin" <b...@herrin.us> said:
> Good question! It matters because a little over two decades ago we had > some angst as equipment configured to emit a TTL of 32 stopped being > able to reach everybody. Today we have a lot of equipment configured > to emit a TTL of 64. It's the default in Linux, for example. Are we > getting close to the limit where that will cause problems? How close? If it's hop-count that's interesting, I think that raises a question on the potential for a sudden large change in the answer, potentially with unforeseen consequences if we do have a lot of devices with TTL=64. Imagine a "tier-1" carrying some non-trivial fraction of Internet traffic who is label-switching global table, with no TTL-propagation into MPLS, and so looks like a single layer-3 hop today. In response to traceroute-whingeing, they turn on TTL-propagation, and suddenly look like 10 layer-3 hops. Having been in the show/hide MPLS hops internal debate at more than one employer, I'd expect flipping the switch to "show" to generate a certain support load from people complaining that they are now "more hops" away from something they care about (although RTT, packet-loss, throughput remain exactly the same). I wouldn't have expected to break connectivity for a whole class of devices. Regards, Tim.
