Network Security Fundamentals [Electronic resources] نسخه متنی

Service Assurance Agent

The Service Assurance Agent (SAA) is embedded software within Cisco IOS devices that performs active monitoring. Before you can understand what an SAA is, you need to understand active monitoring. Active monitoring is an SAA capability that generates and analyzes traffic to measure the performance among several Cisco IOS devices or between an Cisco IOS device and an application server. With active monitoring, you can measure the network performance by using the following:

• Network delay or latency

• Packet loss

• Network delay variation (jitter)

• Availability

• One-way latency

• Website download time

• Network statistics

SAA can be used to measure network health, perform network assessment, verify Service Level Agreements (SLAs), and assist with troubleshooting the network. SAA is supported on almost all Cisco IOS devices.

NOTE

The SAA is a new name for the Response Time Reporter (RTR) feature. SAA retains the use of the RTR acronym in many of the configuration commands. RTR is also used throughout the command-line interface in the output of help and show commands.

SAA is accessible using SNMP, so it can also be used in performance-monitoring applications for NMSs such as CiscoWorks.

To configure SAA, you need to configure operations on the router to collect information such as response time and availability. Operations use synthetic packets that are placed in the network to collect data about that network. These packets simulate other forms of network traffic as determined by the type of operation you are configuring. SAA operations have specific identification numbers so that you can track the various operations you configured on a router. To configure a new SAA operation, use the following steps in configuration mode:

.

The">Figure 15-6 shows two routers connected to each other via an Ethernet interface.

This example shows a PathEcho entry from RouterB to RouterA. Example 15-3 shows the configuration needed to accomplish this.

Example 15-3. CaptionPathEcho Entry

RouterB#
configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
RouterB(config)#
rtr 2 
RouterB(config-rtr)# 
type pathEcho protocol ipIcmpEcho 10.1.1.1 
RouterB(config-rtr)# 
frequency 10 
RouterB(config-rtr)# 
lives-of-history-kept 2 
RouterB(config-rtr)# 
buckets-of-history-kept 1 
RouterB(config-rtr)# 
filter-for-history all 
RouterB(config-rtr)#
exit 

To execute this operation, the following commands must be used:

RouterB(config)#
rtr schedule 2 start-time now life 25 
RouterB(config)#
exit 

This command indicates that operation 2 starts immediately and that it lasts for 25 seconds. If you want to see the outcome of the operation, you can use the

show commands in Example 15-4.

Example 15-4. show rtr Command

RouterB#
show rtr ? 
application               RTR Application
authentication            RTR Authentication Information
collection-statistics     RTR Statistic Collections
configuration             RTR Configuration
distributions-statistics  RTR Statistic Distributions
history                   RTR History
operational-state         RTR Operational State
reaction-trigger          RTR Reaction Trigger
responder                 RTR Responder Information
totals-statistics         RTR Statistics Totals

With

show rtr history , you can see the history of the operation, as demonstrated in Example 15-5.

Example 15-5.

show rtr history Command

RouterB#
sh rtr history 
Point by point History
Entry    = Entry Number
LifeI    = Life Index
BucketI  = Bucket Index
SampleI  = Sample Index
SampleT  = Sample Start Time
CompT    = Completion Time (milliseconds)
Sense    = Response Return Code
Entry LifeI    BucketI    SampleI    SampleT    CompT      Sense      TargetAddr
2     1        1          1          196981662  0          4          255.255.255.255
2     1        1          2          196981662  0          5          10.1.1.1
2     1        1          3          196981662  0          5          10.1.1.1
2     1        1          4          196981662  0          5          10.1.1.1
2     1        1          5          196981662  0          5          10.1.1.1
2     1        1          6          196981662  0          5          10.1.1.1
2     1        1          7          196981662  0          5          10.1.1.1
2     1        1          8          196981662  0          5          10.1.1.1
2     1        1          9          196981662  0          5          10.1.1.1

All other commands can be found in the command reference at the following URL: