RE: linkup linkdown monitoring impacts the performance

On Tue, 7 Mar 2006, vishakha s wrote:

> Date: Tue, 7 Mar 2006 14:23:14 +0530
> From: vishakha s <[email protected]>
> To: 'Peder Chr. Norgaard' <[email protected]>
> Cc: "Net-Snmp-Users (E-mail)" <[email protected]>
> Subject: RE: linkup linkdown monitoring impacts the performance
> 
> Hi
> I read this mail and tried to run with the notification.c you mentioned .It
> is generating the trap .But how to use netlink for this .We have to write
> some code for opening the socket and what you mean by subscribe to link
> change messages.I am not much familiar with this topic .Can you please put
> some more light on this exactly how to implement this netlink concept in
> net-snmp.

I can only repeat what I already wrote to Robert Story last week:  Grab 
the "quagga" package from the net and study it:

--------
The "quagga" package uses netlink much the way I suggest (actually I
looked more in the "quagga" code than in the documentation when I wrote my
own piece).  Look in the file zebra/rt_netlink.c.  The function
netlink_link_change is the place where you recognize the ifUp/ifDown
events - but of course you also need the surrounding infrastructure - the
opening and configuration of the socket, the ordering of this specific
brand of events, the adding of the FD for the socket to the central select
loop etc etc.

I did not find netlink easy to work with - the documentation is sloppy and
complex, and the design is not impressive.  It took me something like two
full weeks, with a lot of cheating = looking in kernel source, to get the
hang of it - but when you know how to work it, it works like a charm.

And for performance it really beats using /proc for almost everything.
--------

--
Peder Chr. Nørgaard        	Senior System Developer, M. Sc.
Ericsson Denmark A/S, Telebit Division
Skanderborgvej 232         	tel: +45 30 91 84 31
DK-8260 Viby J, Denmark         fax: +45 89 38 51 01
          e-mail: [email protected]
(old e-mail 2000-2003: [email protected])
           (old e-mail 1992-2000: [email protected])
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