Switches, Hubs, and Modems
cancel
Showing results for 
Search instead for 
Did you mean: 

excessive src / alignement Errors

rkohlbrenner
Occasional Visitor

excessive src / alignement Errors

i have an hp 4108 GL Switch, and sometimes excessive crc / alignement Errors on different ports..

the firmware ist the latest

in a telnet seesion i also see lots of :

01/01/90 15:48:37 ports: port A3 is now on-line
01/01/90 15:48:40 ports: port A4 is Blocked by LACP
01/01/90 15:48:43 ports: port A4 is now on-line


i didnt find anything usefull on the internet about this, does anyone have some tips for me?

thanks.
4 REPLIES
Terhorst
Trusted Contributor

Re: excessive src / alignement Errors

Hi,

CRC/alignments can indicate bad cabling or patches. Another possibility is mismatching speed/full duplex settings.
These are all RJ-45 10/100 Mbps ports?


Regards,
Alexander
rkohlbrenner
Occasional Visitor

Re: excessive src / alignement Errors

Hi,

the switch hast 3 10 / 100 mb modules and 2 Gbit modules, bit the errors are normally on the 10 / 100 ports.

i already tried to change the duplex settings etc, how can i be sure that it is a cacling / taching problem?
Les Ligetfalvy
Esteemed Contributor

Re: excessive src / alignement Errors

Move a patchcord from a port reporting errors to a port that does not report errors. If the errors move with the patchcord, it is cabling.

If you don't use LACP, you could disable it on selected ports.
Ron Kinner
Honored Contributor

Re: excessive src / alignement Errors

Excessive CRC errors usually indicate that this end is set to full duplex while the other is set to half (or auto which will setup at half if the other side is not at auto). The other end of the circuit will see an ungodly number of collisions. Every time the full duplex end sends something while the half duplex end is sending something the half duplex end will stop sending immediately. This means the full duplex side will receive a lot of incomplete packets which it interprets as CRC and alignment errors.

Remember if one side is set to Auto the other side MUST be set to Auto too or the Auto side has to set up at Half. Don't ask me why that is but it is is a requirement of the RFC. If you use FULL on one end you must use it on the other end or you will have a duplex mismatch.

That said I have seen a few driver updates where they said it corrected a tendency to send packets with bad CRC and at least one switch firmware update where it couldn't calculate them correctly.

Ron