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Ip header checksum fail

Posted: 27 Jul 2016 07:06
by paulierco
Hello all,

I have a strange issue in my environment. I have some logs regarding IP header checksum fail.
I put wireshark and i found two PC involved in this.

The crazy thing is that those logs are repeat in the exact time and second.
ex: if the first one is at 9:00:01 AM in the next hour will be one at exact same time 10:00:01.
This error is repeat at somehow 3-4 minutes but is not a rule here.

The logs looks like this:

Code: Select all

Jul 27 12:49:24 swlogd: ipni data warning(4) 10.1.2.255->255.255.255.255/VRF 0. IP header checksum fail 0xffffb324 != 0. Hdr-cksum=0xf257
Jul 27 12:49:31 swlogd: ipni data warning(4) 10.1.2.255->255.255.255.255/VRF 0. IP header checksum fail 0xffffb322 != 0. Hdr-cksum=0xf257
Jul 27 12:49:31 swlogd: ipni data warning(4) 10.1.2.255->255.255.255.255/VRF 0. IP header checksum fail 0xffffae84 != 0. Hdr-cksum=0xf257
Subnet is 10.1.2.255/24 and there are 8 x 6450-48 with different uplinks ports. (3 stacks)

Here is one log from wireshark.
screen_alcatel.jpg
The question is: Could this do some other problems in this subnet ? I have some users complain about network connectivity and network failed from time to time.

Re: Ip header checksum fail

Posted: 31 Jul 2016 04:25
by cedric1
Hello,

You can“t have source ip .255 as it is a broadcast adresse.

So you have
10.1.2.0/24
network adress is .0
broadcast is .255

address for end device : from .1 to .254

So you have to find computer with ip .255 and your pb will be solved.

Cedric