[j-nsp] L3 incompletes error in gigaethernet interface

[michael.firth at bt.com]

One thing that can cause L3 incomplete messages is if an interface is
receiving multicast packets without multicast reception being enabled by
either having PIM on the Interface, or using the hidden "routing-options
multicast interface xxx enable' option.

Could this be the cause?

Michael



> -----Original Message-----
> From: juniper-nsp-bounces at puck.nether.net 
> [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Dario
> Sent: 11 October 2006 17:01
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] L3 incompletes error in gigaethernet interface
> 
> 
> Dear all,
> 
> I've found an interface that has a lot of L3 incompletes errors.
> 
> This is the information I've found:
> 
> 	L3 incompletes: This counter is incremented when the 
> incoming packet fails Layer 3 (usually IPv4) sanity checks 
> 	of the header. For example, a frame with less than 20 
> bytes of available IP header would be discarded and this 
> 	counter would be incremented.
> 
> 	L3 incomplete means that the datagram received by layer 
> 2 does not have enough data to match the l3 header. 
> 	For example, if you get a 64-byte Ethernet packet where 
> the IP header says length is 200 bytes, that's L3 
> 	Incomplete. Most frequently seen in ATM where a missed 
> cell causes a short packet;  usually but not always the
> 	AAL5 CRC will catch it...
> 
> Does anyone know how juniper router is doing L3 sanity checks 
> of IP header? When only L3 incompletes errors are incremented 
> on Juniper routers, what will be the cause? Is critical? Is 
> there any thereshold (errors/seg) to be aware of?
> 
> Best regards and thanks in advance,
> 
> 	Dario D.
> 	NOC RedIRIS
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