Packet Length greater than MTU Post: 302500397

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Special Forums IP Networking Packet Length greater than MTU Post 302500397 by giles.cardew on Monday 28th of February 2011 12:13:56 PM

02-28-2011

Registered User

Packet Length greater than MTU

Hello,

I would appreciate some help with the following. We have 3 SUN X4450 servers, each of these servers talk to each other, one is an application server the other is a database server and the third is a web server. We also have numerous workstation and ACD connections.

When I snoop the application server I can see the following message a lot and I mean a lot

(warning) packet length greater than MTU in buffer offest

The NIC cards on the servers are all set as 1500 and the customer ensures us each router/switch/firewall has the same MTU.

When I snoop a particular packet I can see the Packet size as 1967 which based on the MTU doesn't seem possible. Also the do not fragment bit it set to 1.

So much questions are this;

1) Would there be a network device that is advertising an MTU greater than 1500
2) Would there be a problem with the Solaris server config, the e1000g.conf file hasn't be changed from the default

Any help would be greatly appreciated as finding where the issues lies is proving rather difficult.

Thanks,
Giles

Last edited by giles.cardew; 02-28-2011 at 01:14 PM.. Reason: grammer and spelling

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LEARN ABOUT OPENSOLARIS

net_getmtu

net_getmtu(9F)						   Kernel Functions for Drivers 					    net_getmtu(9F)

NAME

       net_getmtu - determine the MTU of a given network interface

SYNOPSIS

       #include <sys/neti.h>

       int net_getmtu(const net_data_t net, const phy_if_t ifp);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

PARAMETERS

       net    value returned from a successful call to net_protocol_lookup(9F).

       ifp    value returned from a successful call to net_phylookup(9F) or net_phygetnext(9F).

DESCRIPTION

       The  net_getmtu()  function  receives  information about the current MTU of a network interface. The value returned from this function call
       should not be cached as the MTU of a network interface since it is not guaranteed to be constant.

RETURN VALUES

       The net_getmtu() function returns -1 if the network protocol does not support this feature and otherwise returns the  current  MTU  of  the
       network interface.

CONTEXT

       The net_getmtu() function may be called from user,  kernel, or interrupt context.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+

SEE ALSO

       net_phygetnext(9F), net_phylookup(9F), net_protocol_lookup(9F)

SunOS 5.11							    1 May 2008							    net_getmtu(9F)

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