[ILUG] Re: [Q] Max number of TCP(?) packets without waiting for an ACK(?)

[paul at clubi.ie]

On Tue, 16 Dec 2008, Brian Foster wrote:

> not quite.  he *speculated* that the firewall's complaint
> meant it was having to "remember" too many outstanding
> fragments.

IP Fragments or IP/TCP/? packets (as per a previous email)?

Confusing though it may be, these terms mean different things.

> be (part of ?) the issue!
>
> both my workstation and the IMAP/SMTP-server were doing
> p-mtu-d.  here are the results of our tests:
>
>    W = Workstation's .../ip_no_pmutu_disc setting (≡ ¬p-mtu-d).
>    S = IMAP/SMTP-Server's .... .
>    B = firewall Bypass (workstation whitelisted):  Y(es) N(no).
>    R = Receiving e-mail (IMAP download):  ✓ works, ✗ doesn't work.
>    T = Transmitting e-mail (SMTP upload):  .... .
>
>   Tst  W  S  B ⇒ R  T   Comments...
>   [1]  ?  ?  N   ✓  ✓    Historical situation until some unknown event.
>   [2]  0  0  N   ✗  ✓    "Original" situation that started all this.
>   [3]  0  0  Y   ✓  ✗
>   [4]  1  0  Y   ✓  ✓    Yeah!
>   [5]  1  1  N   ✗  ✓    WTF ?

My font doesn't have glyphs for whatever you've used here. Lowering 
your Unicode-osity might be a good idea.

> have forgotten.   nonetheless, it seems to point the
> finger at MTU-related issue(s?).

Did you say you were using a VPN?

Ask your admin if he has set the firewall to filter out ICMP (not a 
very clueful thing to do - so how come NUIM do it Gavin?). Keep the 
thick copy of Stevens handy, in case he says yes.

regards,
-- 
Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Fortune:
Oh wearisome condition of humanity!
Born under one law, to another bound.
 		-- Fulke Greville, Lord Brooke