Thanks to:
Casper Dik
Benjamin Cline
Bismark Espinoza
Kun Li
Everyone pointed the corrected command:
ndd -set /dev/ip ip_path_mtu_discovery 0
I wanted to try to reset the ip dont fragment bit because my mail
machine was having problem receiving e-mail from some sites. Caper Dik
hit the nail by blaming some router in the ip path. It turn out to be
the mtu of the ppp port on the isp. So thanks to everyone that responded
so promptly.
My original e-mail:
> Hi all,
>
> Since I patched the machines here (solaris 2.5 x86 and solaris 2.5.1
> sparc), the ip do not fragment bit is being set on every packet being
> sent by any of these machines using any interface (ethernet or PPP).
>
> The machines are solaris 2.5 x86 and sparcs with solaris 2.5.1 with
the
> latest patches avaiable on 07/15/98.
>
> Does anyone know how to turn thus the ip do not frag bit off ?. Or
> I should remove the latest patch 103170-13 for x86 and the equivalent
> for Solaris 2.5.1?.
>
> Has anyone seen the same problem?. This is breaking havoc with my
> internet connections and e-mails.
>
> Thank you,
The responses where:
-----------------------------------------------------
Casper Dik wrote:
> This is a standard IP freature being used (PATH MTU discovery)
> This has been on in Solaris 2.x since forever.
>
> The solaris FAQ says:
>
> 6.20) Solaris 2.x can't set up any TCP/IP connections to certain
> hosts.
>
> Solaris 2.x sets the don't fragment bit on all packets it send
> as part of MTU path discovery. The Solaris 2.x implementation
> is RFC compliant, but the MTU path discovery protocol will
> fail when there are broken routers in the path.
> Typical symptom is not being able to connect from a
> Solaris 2.x hosts but having no trouble from other hosts or
> being able to start a TCP/IP connection but not move any
> significant amount of data.
>
> /usr/sbin/ndd -set /dev/ip ip_path_mtu_discovery 0
>
> (See also 6.18)
>
> --- end of excerpt from the FAQ
>
> Questions marked with a * or + have been changed or added since
> the FAQ was last posted
>
> The most recently posted version of the FAQ is available from
> <http://www.wins.uva.nl/pub/solaris/solaris2/>
-----------------------------------------------------
Benjamin Cline wrote:
> This sounds like it might be a problem with the Solaris 2 MTU path
> discovery (RFC 1191).
>
> The Solaris 2 FAQ (http://www.wins.uva.nl/pub/solaris/solaris2.html)
> says:
> 5.19) Solaris 2.x can't set up any TCP/IP connections to certain
> hosts.
>
> Solaris 2.x sets the don't fragment bit on all packets it send as part
> of
> MTU path discovery. The Solaris 2.x implementation is RFC compliant,
> but
> the MTU path discovery protocol will fail when there are broken
> routers in
> the path. Typical symptom is not being able to connect from a Solaris
> 2.x
> hosts but having no trouble from other hosts or being able to start a
> TCP/IP connection but not move any significant amount of data.
>
> /usr/sbin/ndd -set /dev/ip ip_path_mtu_discovery 0
>
> (See also 5.17)
-----------------------------------------------------
Bismark Espinoza wrote:
> # /usr/sbin/ndd_set /dev/ip ip_path_mtu_discovery 0
-----------------------------------------------------
Kun Li wrote:
> put the following command in your /etc/init.d/inetinit file , and
> reboot .
>
> ndd -set /dev/ip ip_path_mtu_discovery 0
>
> but I can't see any reason to do this. almost all my mechine work
> fine
> with this
> parameter setting to 1.
>
-----------------------------------------------------------------
Alexandre Peixoto Ferreira Telefone: (048) 281-7083
Diretor de Produtos Fax: (048) 281-7099
Flug Telematica e Automacao Ltda
Rua Prof. Sofia Quint de Souza, 99
Florianopolis-SC 88085-040
e-mail: alexandre.ferreira@flug.com.br
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