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Netstat column graph, retrans

4 messages in this thread

list Sigurður Guðbrandsson · Tue, 9 Sep 2008 17:32:49 -0000 ·
Hi.
 
I am wondering about the netstat column's graph, specifically the retrans.
 
The things I am wondering about are, what does this stand for (e.g. is it the retransmission timeout of packets or amount of packets retransmitted)?
Also, what is a high value for this?
 
The reason I ask of this is because I have not found any solid answers using either google or searching the mailing list.
 
With regards,
 Sigurður Guðbrandsson
list Greg L Hubbard · Tue, 9 Sep 2008 13:09:30 -0500 ·
It probably refers to the number of packets that had to be retransmitted regardless of reason.  A low number is not a problem ("stuff" happens), but a high number can indicate a problem somewhere in a network.  The host reporting the retransmissions could be part of the problem (misconfigured link, perhaps) or it could be a "vicitm" of problems elsewhere -- congestion, duplex mismatches, dirty circuits, etc.
 
GLH
quoted from Sigurður Guðbrandsson


	From: Sigurður Guðbrandsson [mailto:user-f6f2e0690a1f@xymon.invalid] 
	Sent: Tuesday, September 09, 2008 12:33 PM
	To: user-ae9b8668bcde@xymon.invalid
	Subject: [hobbit] Netstat column graph, retrans
	
	
	Hi.
	 
	I am wondering about the netstat column's graph, specifically the retrans.
	 
	The things I am wondering about are, what does this stand for (e.g. is it the retransmission timeout of packets or amount of packets retransmitted)?
	Also, what is a high value for this?
	 
	The reason I ask of this is because I have not found any solid answers using either google or searching the mailing list.
	 
	With regards,
	 Sigurður Guðbrandsson
list Anna Jonna Armannsdottir · Tue, 09 Sep 2008 18:36:25 +0000 ·
quoted from Sigurður Guðbrandsson
On þri, 2008-09-09 at 17:32 +0000, Sigurður Guðbrandsson wrote:
The things I am wondering about are, what does this stand for (e.g. is
it the retransmission timeout of packets or amount of packets
retransmitted)?
Hi Sigurður, please have a look at e.g. :
http://www.hswn.dk/hobbit-cgi/bb-hostsvc.sh?CLIENT=voodoo.hswn.dk 
In the [netstat] section is a TcpExt section. It contains a number of retransmission counts and I guess it is the sum of those counts that is graphed. The important thing is that it is packet counts that is graphed. 
-- 
Kindest Regards, Anna Jonna Ármannsdóttir,       %&   A: Because people read from top to bottom.
Unix System Aministration, Computing Services,   %&   Q: Why is top posting bad?
University of Iceland.
list Henrik Størner · Tue, 30 Sep 2008 13:21:21 +0000 (UTC) ·
In <user-4f9a30ea570f@xymon.invalid> =?iso-8859-1?Q?Sigur=F0ur_Gu=F0brandsson?= <user-f6f2e0690a1f@xymon.invalid> writes:
I am wondering about the netstat column's graph, specifically the =
retrans.
These data usually come from the operating system "netstat -s" command,
so you should check the OS docs to see what those are.

It is normally the number of packets retransmitted over a 5 minute
average (so it should be *really* low unless you have network problems).


Henrik