That is a stellar TCL script! I generally use netflow to glean information regarding average packet size. show ip cache-flow will provide it via the CLI, or a netflow collector will graph it statistically over time. Chris On Thu, May 20, 2010 at 6:05 PM, Thomas Magill <tmagill@providecommerce.com>wrote:
I had to come up with a way to monitor average packet size on an interface so I wrote the following script (cisco devices). I don't know if anyone finds it useful, but here it is if so. Also, there is one issue with it where if the total number of packets an interface has seen is over 7 digits, it will not calculate it. This appears to be a limitation of the expr command used in cisco TCL and mpexpr is not supported. If anyone else knows a way to bypass this issue I would be glad to hear it. For now it just tells you that the value is too high. I am also considering creating a job that can input the value into an OID that we can poll but not exactly sure how to do that so if anyone has any experience or good references (other than the cisco stuff I find on google) I would be thankful.
I save this to flash: or disk: (depending on default tcl location per device) and assign the alias:
alias exec psize tclsh psize.tcl
Then use it like:
Router#psize psize tun1
Packet Size Information for Tunnel1
----------------------------------------------------
5 minute input bits/sec = 43000
5 minute input packets/sec = 30
5 minute average packet size = 179 Bytes
----------------------------------------------------
5 minute output bits/sec = 3000
5 minute output packets/sec = 3
5 minute average packet size = 125 Bytes
----------------------------------------------------
Total input bytes = 1678803
Total input packets = 7761
Total average packet size = 216 Bytes
----------------------------------------------------
Total output bytes = 133316
Total output packets = 1041
Total average packet size = 128 Bytes
----------------------------------------------------
This is my first attempt at a script this complex so if you have any input/suggestions they are welcome.
######################################################################## #####
# #
# psize.tcl #
# By Thomas Magill - 5/7/2010 #
# #
######################################################################## #####
#
# Get input from command line
set ifname $argv
# Check interface name for errors
if {[string equal $ifname ""]} { puts "Usage: psize ifname"; return; }
if { [ catch { exec "show ip interface $ifname" } errmsg ] } {
puts "Invalid interface $ifname, command failed"; return}
set cmdtext [ exec "show interface $ifname" ]
# Pull interface information and calculate
foreach line [split $cmdtext "\n"] {
if {[regexp -nocase {^(\S+) is (.*), line protocol is (\S+)} $line ignore ifnamefull ifstatus iflinkstatus]} {
}
if {[regexp -nocase {5 minute input rate ([0-9]+) bits/sec, ([0-9]+) packets/sec} $line ignore bpsinfive ppsinfive]} {
if {$ppsinfive == "0"} {set psizeinfive "0"} else {set psizeinfive [expr $bpsinfive / $ppsinfive]}
set psizeinfive [expr $psizeinfive / 8]
}
if {[regexp -nocase {5 minute output rate ([0-9]+) bits/sec, ([0-9]+) packets/sec} $line ignore bpsoutfive ppsoutfive]} {
if {$ppsoutfive == "0"} {set psizeoutfive "0"} else {set psizeoutfive [expr $bpsoutfive / $ppsoutfive]}
set psizeoutfive [expr $psizeoutfive / 8]
}
if {[regexp -nocase {([0-9]+) packets input, ([0-9]+) bytes} $line ignore ppsintotal bpsintotal]} {
if {$ppsintotal > "9999999"} {set psizeintotal "Too Large to Find"} elseif {$ppsintotal == "0"} {set psizeintotal "0"} else {set psizeintotal [expr $bpsintotal / $ppsintotal]}
}
if {[regexp -nocase {([0-9]+) packets output, ([0-9]+) bytes} $line ignore ppsouttotal bpsouttotal]} {
if {$ppsouttotal > "9999999"} {set psizeouttotal "Too Large to Find"} elseif {$ppsouttotal == "0"} {set psizeouttotal "0"} else {set psizeouttotal [expr $bpsouttotal / $ppsouttotal]}
}
}
# Output Data
puts "\n\nPacket Size Information for $ifnamefull"
puts "---------------------------------------------------------"
puts " 5 minute input bits/sec = $bpsinfive "
puts " 5 minute input packets/sec = $ppsinfive "
puts " 5 minute average packet size = $psizeinfive Bytes "
puts "---------------------------------------------------------"
puts " 5 minute output bits/sec = $bpsoutfive "
puts " 5 minute output packets/sec = $ppsoutfive "
puts " 5 minute average packet size = $psizeoutfive Bytes "
puts "---------------------------------------------------------"
puts " Total input bytes = $bpsintotal "
puts " Total input packets = $ppsintotal "
puts " Total average packet size = $psizeintotal Bytes "
puts "---------------------------------------------------------"
puts " Total output bytes = $bpsouttotal "
puts " Total output packets = $ppsouttotal "
puts " Total average packet size = $psizeouttotal Bytes "
puts "---------------------------------------------------------"
Thomas Magill Network Engineer
Office: (858) 909-3777
Cell: (858) 869-9685 mailto:tmagill@providecommerce.com <mailto:tmagill@providecommerce.com>
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