Configuring The Ip Slas Responder; Analyzing Ip Service Levels By Using The Udp Jitter Operation - Cisco Catalyst 3120 Software Manual

Configuring IP SLAs Operations

Configuring the IP SLAs Responder

The IP SLAs responder is available only on Cisco IOS software-based devices, including some Layer 2
switches that do not support full IP SLAs functionality, such as the Catalyst 2960 or the Cisco ME 2400
switch. Beginning in privileged EXEC mode, follow these steps to configure the IP SLAs responder on
the target device (the operational target):
Command
Step 1
configure terminal
Step 2 ip sla responder {tcp-connect |
udp-echo} ipaddress ip-address port
port-number
Step 3
end
Step 4 show ip sla responder
Step 5
copy running-config startup-config
To disable the IP SLAs responder, enter the no ip sla responder global configuration command. This
example shows how to configure the device as a responder for the UDP jitter IP SLAs operation in the
next procedure:
Switch(config)# ip sla responder udp-echo 172.29.139.134 5000

Analyzing IP Service Levels by Using the UDP Jitter Operation

Jitter means interpacket delay variance. When multiple packets are sent consecutively 10 ms apart from
source to destination, if the network is behaving correctly, the destination should receive them 10 ms
apart. But if there are delays in the network (like queuing, arriving through alternate routes, and so on)
the arrival delay between packets might be more than or less than 10 ms with a positive jitter value
meaning that the packets arrived more than 10 ms apart. If the packets arrive 12 ms apart, positive jitter
is 2 ms; if the packets arrive 8 ms apart, negative jitter is 2 ms. For delay-sensitive networks, positive
jitter values are undesirable, and a jitter value of 0 is ideal.
In addition to monitoring jitter, the IP SLAs UDP jitter operation can be used as a multipurpose data
gathering operation. The packets IP SLAs generates carry packet sending and receiving sequence
information and sending and receiving time stamps from the source and the operational target. Based on
these, UDP jitter operations measure this data:
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Purpose
Enter global configuration mode.
Configure the switch as an IP SLAs responder.
The keywords have these meanings:
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Note
Return to privileged EXEC mode.
Verify the IP SLAs responder configuration on the device.
(Optional) Save your entries in the configuration file.
Per-direction jitter (source to destination and destination to source)
Per-direction packet-loss
Chapter 41
tcp-connect—Enable the responder for TCP connect operations.
udp-echo—Enable the responder for User Datagram Protocol (UDP)
echo or jitter operations.
ipaddress ip-address—Enter the destination IP address.
port port-number—Enter the destination port number.
The IP address and port number must match those configured on
the source device for the IP SLAs operation.
Configuring Cisco IOS IP SLAs Operations
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