Friday, December 04, 2015

QoS conversions and testing with extended ping commands - version 2

Years ago I posted a tip regarding using Cisco IOS devices' extended ping capabilities to emulate traffic with various QoS / quality of service markings.  You can find the original post here: http://webmaxtor.blogspot.com/2010/08/qos-conversions-for-extended-pings.html

Recently I happened upon a great post at http://www.netcontractor.pl/blog/ that provides a JPG with more complete examples of various DSCP, tos, IP precedence, etc. values.  The latest version current appears at http://www.netcontractor.pl/blog/?p=1161.  Thank you to Netcontractor.pl for putting that together.

Here is their current v3 chart:


Below is the body of my post showing how to use the Cisco IOS ping command to tag ICMP traffic with various markings.  Using the TOS values from the table above you should be able to emulate just about any traffic type for QoS class map testing:

QoS conversions for extended pings sample

To emulate DSCP tagged traffic:

ef = dscp 46 = 101110 = tos 0xb8 (184) = ip prec 5
af31 = dscp 26 = 011010 = tos 0x68 (104) = ip prec 3
af32 = dscp 28 = 011100 = tos 0x70 (112) = ip prec 3
cs3 = dscp 24 = 011000 = tos 0x60 (96) = ip prec 3

voice_gw#ping ip
Target IP address: 10.10.10.1
Repeat count [5]: 100
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 10.20.10.1
Type of service [0]: 184 --->dscp is ef
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.

A simple way to calculate is to put your binary representation of the value into your calculator and add two zeros to the end (i.e. 101110 becomes 10111000).

If you are looking to emulate IP Precedence values, use 224,192,160,128,96,64,32,0 for IPP 7 to 0

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