Re: [gentoo-user] PMTUD

[Grant <emailgrant@gmail.com>]

> The hotel's router/modem may be using PPPoE to authenticate with their ISP,
> which has a larger header size and requires an MTU of 1492 (1464+28=1492)
>
> So, although your NIC is configured to the full ethernet MTU size, the router
> drops the size down to 1492 to be able to squeeze it out through the ISP's
> network.  That's all good and proper and will not cause the timeout problem
> you have been experiencing.

OK, does PMTUD lower the outgoing packet size on my system due to the
hotel router's lower MTU or does the hotel router itself fragment my
1500 byte packets in order to send them out?  Just curious.

> Have you checked that the firewall at your server is not set to drop all ICMP
> packets and that you don't have something like this set up on it:
>
>   net.ipv4.icmp_echo_ignore_all = 0
>
> (use sysctl to check)

I get this which looks OK:

# sysctl -a|grep icmp_echo_ignore_all
net.ipv4.icmp_echo_ignore_all = 0

Nikos mentioned in the other thread that I may need to configure ICMP
on my server's modem/router which I will be able to try tomorrow.

- Grant