People using NetFlow Analyzer
wonder, what these reports DSCP, TOS actually means ? Here is the
blog which explain more detail about these fields.

The NetFlow packets exported from the
device originally contains ToS value on each flow. From the ToS
value, the analyzing software derives the DSCP.

Type of Service (TOS):-

The Type of Service field is present in
IP Header and it was originally defined in RFC 791.

The Type of Service octet consists of
three fields. The last 3 bits ( 7,6,5) are for the first field,
labeled “Precedence” , intended to denote the importance
or priority of the datagram. The second field, labeled “TOS”
, denotes how the network should make tradeoffs between throughput,
delay, reliability, and cost.The first field, labeled “MBZ”
( for “must be zero” ) above, is currently unused. The
originator of a datagram sets this field to zero (unless
participating in an Internet protocol experiment which makes use of
that bit). Routers and recipients of datagrams ignore the value of
this field. This field is copied on fragmentation.

DSCP(Differentiated Service Code
Point)

The definition to ToS was entirely
changed in the RFC 2474 and it is now been called as Differentiated
Service (DS). On the 8 fields, the upper 6 bit contains value called
Differentiated Service Code Point(DSCP). The last 2 bits are used for
Explicit Congestion Notification and it is defined in RFC 3168.

Given below are the interpretation
of ToS and DSCP fields:

DSCP interpretation (RFC2474) :

RFC791/1349:

In DSCP the most
significant three bits are directly proportional to IP Precedence,
The below table explains on DSCP to IP precedence Conversion table.

DSCP Name	DS Field Value		IP Precedence
	Binary	Decimal
CS0	000 000	0	0
CS1	001 000	8	1
AF11	001 010	10	1
AF12	001 100	12	1
AF13	001 110	14	1
CS2	010 000	16	2
AF21	010 010	18	2
AF22	010 100	20	2
AF23	010 110	22	2
CS3	011 000	24	3
AF31	011 010	26	3
AF32	011 100	28	3
AF33	011 110	30	3
CS4	100 000	32	4
AF41	100 010	34	4
AF42	100 100	36	4
AF43	100 110	38	4
CS5	101 000	40	5
EF	101 110	46	5
CS6	110 000	48	6
CS7	111 000	56	7

NetFlow Analyzer
DSCP and TOS Reports:-

NetFlow Analyzer
reports on both DSCP and TOS, the DSCP report generated from NetFlow
Analyzer will show each DSCP marking traffic utilization and
application and conversation marked for DSCP.

The TOS report
will show corresponding ToS values for each DSCP.

Click here to know about Cisco recommended QoS base lines. 

For 30 Day Trial, click Download now.

Thanks and Regards

Praveen Kumar

You Can Learn More About the ManageEngine Product Line By Going to manageengine.optrics.com

The original article/video can be found at Understanding IP Precedence, TOS & DSCP