Specifications

© 2006 Cisco Systems, Inc.
All rights reserved.
Product Features 2-100
NAM / Traffic Analyzer v3.5 Tutorial
© 2006 Cisco Systems, Inc. All rights reserved.
Product Features 2-100
NAM / Traffic Analyzer v3.5 Tutorial
Enabling Traffic Monitoring
DiffServ Overview
Enabling Traffic Monitoring
DiffServ Overview
NAM-Embedded Traffic Analyzer
DSMON
MIB
DSMON
MIB
FTP
FTP
SNMP
ICMP
http
FTP
SNMP
Ethernet Header
Ethernet Header
IP Header
IP Header
TCP Header
TCP Header
Ethernet
Ethernet
FTP Data
FTP Data
(DSCP0)
(DSCP0)
(
(DSCP0
)
)
(DSCP0)
(DSCP0)
(DSCP24)
(DSCP24)
(DSCP24)
(DSCP24)
(DSCP26)
(DSCP26)
(DSCP40)
(DSCP40)
DiffServ Monitoring Overview
The NAM also supports the ability to monitor and report DiffServ statistics using DSMON, a standard defined
for monitoring Differentiated Services type traffic. Before we cover how to configure the NAM to monitor
DiffServ, let’s review a few basic DiffServ concepts.
DiffServ offers a method for implementing quality of service on a per-packet basis. In DiffServ, the 8-bit Type
of Service (ToS) field in the IP header is replaced by the DS field, which identifies for DiffServ-enabled
routers a value to determine how to handle the packet at each hop along a path. The first six bits of the DS
field contain the DiffServ code point (DSCP). These 6 bits provide 64 different code points for defining how a
forwarding device will handle the packet. In addition, classes are defined in DiffServ that determine how
traffic in a class is handled and how resources within DiffServ-enabled routers are allocated on a per-class
basis.
DSMON is MIB extension for monitoring DiffServ, and it offers statistics based on the code points defined in
the DS field. The NAM offers the following DiffServ monitoring options:
• The percentage of traffic by DSCP—This can be used to validate your planning assumptions and
implementation of quality-of-service (QoS) allocations.
• Protocols within a DiffServ DSCP—This can be used to detect incorrectly marked or unauthorized
traffic.
• Protocol distribution within a DiffServ class—Again, you can use this to validate your QoS plan.
• Host statistics by DSCP
• Conversation statistics by DSCP and application.
Let’s look now at the setup features for monitoring DiffServ.