GSR dropping ICMP packets in a pattern based on size
I have two GSRs and two different DS-3 linecards which are behaving the same way. At the moment both lincards have been tested with a hard loop from tx to rx, and no matter what i do i cannot pass packets with 100% sucess rate when they are larger than 450 bytes. the standard MTU in the interface is 4470, and im not even coming close to that. in addition, the debugs that i am using, debug interface, debug serial packet, debug ip ICMP... show no errors occurring. everything seems to be encapsulted ans sent just fine, and my error counters on the interface do not increment.
I appreciate the help and reccomendations, thanks!
Cisco Internetwork Operating System Software
IOS (tm) GS Software (GSR-P-M), Version 12.0(24)S, EARLY DEPLOYMENT RELEASE SOFT
Re: GSR dropping ICMP packets in a pattern based on size
I guess the issue has something to do with the line resistance. As per the ping result, after each 6 packets, one packet is lost. Without the debug output, it will be very difficult to troubleshoot.
You can do the following for troubleshooting: After giving the hard loop, give an extended ping and give "yes" for extended commands.
The following is the procedure for isolating the trouble:
Type: ping ip
Target address = enter the IP address of the interface to which IP address was just assigned
Repeat count = 50
Datagram size = 1500
Timeout = press ENTER
Extended cmds = yes
Source Address = press ENTER
Type of service = press ENTER
Set Df bit in ip header = press ENTER
Validate reply data = press ENTER
Data pattern: 0x0000
Press ENTER three times.
Notice that the ping packet size is 1500 bytes, and that we are performing an all zeros ping (0x0000).
Examine the show interfaces serial command output and determine if input errors have increased. If input errors have not increased, the local hardware (DSU, cable, router interface card) is probably in good condition.
Perform additional extended pings with different data patterns.
Repeat step 1, but use a Data Pattern of 0x0001
Repeat step 1, but use a Data Pattern of 0x0101
Repeat step 1, but use a Data Pattern of 0x1111
Repeat step 1, but use a Data Pattern of 0x5555
Repeat step 1, but use a Data Pattern of 0xffff
If all pings are 100 percent successful and there are no errors, then the hardware should be good. The problem is either a cabling or Telco issue.
I can suggest you one more thing for ease of troubleshooting. It will be good if you change the encapsulation from HDLC to PPP since troubleshooting will be much more easier in PPP.
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