[ECOS] Is arpresolve() good to get ARP started on an IP address?

[ECOS] Is arpresolve() good to get ARP started on an IP address?

[Tad]

SNMP agent is dropping coldstart and LinkUp traps since ARP table comes 
up without entries

I'll try to fix, but I need to attempt to get snmp read config started 
on resolving the trapsink IP address.

What's the best/easiest way?  arpresolve()?  Ping?...  The arp routines 
seem a bit messy to use for something simple.


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Re: [ECOS] Is arpresolve() good to get ARP started on an IP address?

[Andrew Lunn]

On Tue, Jun 19, 2007 at 12:19:50PM -0800, Tad wrote:
> SNMP agent is dropping coldstart and LinkUp traps since ARP table comes 
> up without entries

Maybe i don't understand what you are saying, but if there is no ARP
entry, the IP packet which needs to be sent is normally queued and an
ARP request is sent out. Once an ARP reply is received the queues
packet is then sent. Is this not happening?

       Andrew

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Re: [ECOS] Is arpresolve() good to get ARP started on an IP address?

[Tad]

Andrew Lunn wrote:
> On Tue, Jun 19, 2007 at 12:19:50PM -0800, Tad wrote:
>   
>> SNMP agent is dropping coldstart and LinkUp traps since ARP table comes 
>> up without entries
>>     
>
> Maybe i don't understand what you are saying, but if there is no ARP
> entry, the IP packet which needs to be sent is normally queued and an
> ARP request is sent out. Once an ARP reply is received the queues
> packet is then sent. Is this not happening?
ARP will only que one mbuf, then drops it if more come in  If a
coldstart and 2 link-up traps occur at powerup, and if we have 2
trapsinks, for example, that's 6 msgs of which 4-5 are dropped.  I need
to update the ipdropped snmp stats counter too, cause it took awhile to
figure out where the missing packets were going.  Looked tricky to use
arpresolve? without dropping any mbuf queued there also.




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Re: [ECOS] Is arpresolve() good to get ARP started on an IP address?

[Andrew Lunn]

On Tue, Jun 19, 2007 at 03:13:18PM -0800, Tad wrote:
> Andrew Lunn wrote:
> >On Tue, Jun 19, 2007 at 12:19:50PM -0800, Tad wrote:
> >  
> >>SNMP agent is dropping coldstart and LinkUp traps since ARP table comes 
> >>up without entries
> >>    
> >
> >Maybe i don't understand what you are saying, but if there is no ARP
> >entry, the IP packet which needs to be sent is normally queued and an
> >ARP request is sent out. Once an ARP reply is received the queues
> >packet is then sent. Is this not happening?
> ARP will only que one mbuf, then drops it if more come in  If a 
> coldstart and 2 link-up traps occur at powerup, and if we have 2 
> trapsinks, for example, that's 6 msgs of which 4-5 are dropped.  I need 
> to update the ipdropped snmp stats counter too, cause it took awhile to 
> figure out where the missing packets were going.  Looked tricky to use 
> arpresolve? without dropping any mbuf queued there also.

Ah, O.K. Well, two comments:

SNMP is designed to be unreliable. It uses UDP. So this is acceptable
behaviour.

You could change the single mbuf into a queue. All the macros to do
this exist, so i doubt it would be too big a job.

     Andrew

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