SUMMARY : mbuf map full

From: Marcello Frutig (
Date: Fri Sep 27 1991 - 04:16:36 CDT


first of all, my apologize to not post this summary before.

Here is my original question :

        Could someone please tell me the reasons for these messages :

        Sep 19 21:10:18 vialactea vmunix: mbuf map full
        Sep 19 21:10:58 vialactea vmunix: le0: out of mbufs - packet dropped

Here is the complete technical explanation that I received from Hal Stern :

"you are running out of mbufs. an mbuf is a wrapper for an ethernet
packet (they're used for other things too, but network traffic is by
far the biggest consumer). in order to send or receive a packet,
it must be wrapped up in an mbuf. to see your usage, use netstat -m

normally, mbufs are allocated as they're needed. there is however
an upper bound -- usually about 1Mbyte worth of mbufs. you've
allocated too many, and the mbuf map (that tells the kernel where
they are) has run out of room. as a result, the network protocol
drivers can't wrap up their packets, so they discard them."

As my network traffic was the same, I imagined that this was not the
case here. I received replies stating that could be a transceiver problem.
So, I started to search it and finally discovered that it really was
a problem with a bad BNC connector ! The messages disappeared and the system
is ok again.

BTW, if your problem is a heavy network traffic, you can install a patch from
Sun to increase the size of the mbuf map from 1M to 2 Mbytes. I don't know
the patch number...

Thanks a lot to : (Eckhard Rueggeberg)
aimla!ruby!jennine@uunet.UU.NET (Jennine Townsend)
stern@sunne.East.Sun.COM (Hal Stern - Consultant)

 Marcello Frutig E-Mail :
 Network Manager Voice : +55 21 529 9422
 Catholic University of Rio de Janeiro - BRAZIL

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