RE: PPPoA vs. PPPoE [was: Whom do I complain about from this traceroute]

On 11/08/2012 12:48 AM, Trent W. Buck wrote:

...

Hmm, alpha is using PPPoA (to an onboard solos card). I thought PPPoA had a higher MTU than PPPoE... was that just my imagination?

Correct, PPPoA supports an MTU of 1500, but PPPoE has 8 more bytes of overhead, reducing this to 1492.

There are lots of placebo anecdotes to argue the merits of either one.

And some ISP's blindly use an MTU of 1492 (or lower) anyway. If the OP is having trouble reaching an external website then a traceroute from the OP to the website isn't going to be that useful. What is required is a traceroute from somewhere with a 1500 byte MTU back to the OP to see if ICMP fragmentation required packets are being generated or if there is a PMTU blackhole. James