Have you got packet captures for SNMP requests. Even if jumbo frames
enabled does the SNMP datagrams are really that big (>1500)
On 16 Sep 2015 20:38, "Lee" <ler...@gmail.com> wrote:
> On 9/16/15, AR, Giridhar <giridhar.raja...@netapp.com> wrote:
> > Hi Lee,
> >
> > Thanks for the response.
> > No I didn't change the MTU on every router and switches between client
> and
> > server.
> >
> >>What is the relation between MTU and max_repetitions.?
> >> If we change the MTU to jumbo frame like 9000, what should be these
> >> macros (SNMP_MAX_MSG_SIZE , SNMP_MAX_LEN ) should be set ?
> >> Is there any other changes in need to perform?
> >
> > Do you have any inputs on the above questions?
>
> Don't change the MTU. If you do, and don't change the MTU on your
> routers & switches, anything you send > 1500 bytes will be dropped.
>
> I'm not exactly sure what you're trying to accomplish, but if I was
> trying to change how much info could be returned I'd start with
> changing SNMP_MAX_MSG_SIZE and see if that worked.
>
> Regards,
> Lee
> >
> > Thanks
> > Giridhar
> >
> > -----Original Message-----
> > From: Lee [mailto:ler...@gmail.com]
> > Sent: Wednesday, September 16, 2015 5:13 PM
> > To: AR, Giridhar
> > Cc: net-snmp-coders@lists.sourceforge.net
> > Subject: Re: guidelines to increase the MTU size
> >
> > On 9/16/15, AR, Giridhar <giridhar.raja...@netapp.com> wrote:
> >> Hi
> >>
> >> Need guidelines to increase the MTU size (example from 1500 to 9000)
> >> Our application is using snmpv2. When the MTU size (9000) is changed
> >> on interface of client and server, Snmp queries are timed out.
> >
> > Did you also change the MTU on every router & switch between the client
> and
> > server to be 9000? If no, that's probably why queries are timing out
> >
> > Regards,
> > Lee
> >
> >
> >> We collected the packet traces on both client and server. Client is
> >> receiving the response from server, but client is dropping the packet.
> >> Following are the test cases tried
> >>
> >> case client MTU server MTU
> >> result
> >>
> >> 1 1500 1500
> >> passed
> >>
> >> 2 1500 9000
> >> failed
> >>
> >> 3 9000 1500
> >> passed
> >>
> >> 4 9000 9000
> >> failed
> >>
> >>
> >> Looked at the client code, uses the net-snmp-code,
> >>
> >>
> >>
> >> #define SNMP_MAX_MSG_SIZE 1472
> >> #define SNMP_MAX_LEN 1500
> >>
> >> And by default max_repetitions is set 20. If we set to 1, snmp queries
> >> are successful.
> >>
> >> What is the relation between MTU and max_repetitions.?
> >> If we change the MTU to jumbo frame like 9000, what should be these
> >> macros (SNMP_MAX_MSG_SIZE , SNMP_MAX_LEN ) should be set ?
> >> Is there any other changes in need to perform?
> >>
> >>
> >> Thanks
> >> Giridhar
> >>
> >>
> >>
> >>
> >>
> >>
> >
>
>
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