While browsing I happened to stumble across this bug report: Cat3750: Frames not counted as input packets on a dot1Q trunk
Symptoms: On a Catalyst 3750, packets of size 64 to 67 bytes (including the dot1Q tag) that ingress the switch on a dot1Q trunk will not be counted under the show interface command as input packets. Workaround: There is no workaround I remember being vaguely aware of this issue, that the hardware will treat these frames as "runts" after the dot-1q header is stripped away from the packet. I also remember that this doesn't affect forwarding in the least; it only affects how packets are counted at the interface. However, it started me thinking... Are there further ramifications to this "cosmetic" problem? For instance, will the counters reported up to SNMP be likewise affected? Will all the 64-byte packets be missed completely when building my RRD graphs showing packets/sec over units of time? Will the bits/sec speeds reported be lower, because the 64-byte packets are not counted towards those totals, as well? Suppose that some miscreant is sending thousands of tiny packets through my switch's trunk ports? Will I be unable to see them reflected in my packet counters? Will I be unable to notice the bandwidth surge in my graphs? Essentially my question boils down to: Is it ONLY the "show interface" command that will give incorrect results? Or will the SNMP counters and bandwidth counters be likewise incorrect? -- David DeSimone == Network Admin == f...@verio.net "I don't like spinach, and I'm glad I don't, because if I liked it I'd eat it, and I just hate it." -- Clarence Darrow This email message is intended for the use of the person to whom it has been sent, and may contain information that is confidential or legally protected. If you are not the intended recipient or have received this message in error, you are not authorized to copy, distribute, or otherwise use this message or its attachments. Please notify the sender immediately by return e-mail and permanently delete this message and any attachments. Verio, Inc. makes no warranty that this email is error or virus free. Thank you. _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/