active-probe (PfR)
To configure a Performance Routing (PfR) active probe for a target prefix, use the active-probe command in PfR master controller configuration mode. To disable the active probe, use the no form of this command.
active-probe probe-type ip-address target-port number [codec codec-name]
no active-probe probe-type ip-address
Syntax Description
probe-type |
Type of probe. Must be one of the following:
|
ip-address |
Target IP address of a prefix to be monitored using the specified type of probe. |
target-port |
(Not specified for echo probes.) Specifies the destination port number for the active probe. |
number |
Port number in the range from 1 to 65535. |
codec |
(Optional) Only used with the jitter probe type. Specifies the codec value used for Mean Opinion Score (MOS) calculation. |
codec-name |
(Optional) Codec value, must be one of the following:
|
Command Default
No active probes are configured.
Command Modes
PfR master controller configuration (config-pfr-mc)
Command History
Release |
Modification |
---|---|
15.1(2)T |
This command was introduced. |
15.0(1)S |
This command was integrated into Cisco IOS Release 15.0(1)S. |
Cisco IOS XE Release 3.3S |
This command was integrated into Cisco IOS XE Release 3.3S. |
Usage Guidelines
The active-probe command is entered on a PfR master controller.
This command is used to optionally configure a master controller to command a border router to transmit active probes to a target IP address or prefix. The active probe is used to measure the delay (round-trip response time) of the target prefix to determine the performance of the current exit and to detect if the prefix is out-of-policy. The border router collects these performance statistics from the active probe and transmits this information to the master controller, which uses this information to optimize the prefix and to select the best available exit based on default and user-defined policies. The performance information is applied to the most specific optimized prefix, which includes the active probe host address. If the prefix is optimized and is currently using the best in-policy exit link, the master controller does not take any action.
Active probing requires you to configure a specific host or target address. The target address can also be learned by PfR through the NetFlow or Top Talker and Delay learning functionality. Active probes must be sent out of a PfR-managed external interface, which may or may not be the preferred route for an Optimized Prefix. PfR can be configured to use the following four types of active probes:
-
ICMP Echo--A ping is sent to the target address. Configuring an ICMP echo probe does not require knowledgeable cooperation from the target device. However, repeated probing could trigger an Intrusion Detection System (IDS) alarm in the target network. If an IDS is configured in a target network that is not under your administrative control, we recommend that you notify the target network administration entity.
-
Jitter--A jitter probe is sent to the target address. A target port number must be specified. A remote responder must be enabled on the target device, regardless of the configured port number. An optional codec value can be configured. The codec value is required for Mean Opinion Score (MOS) calculations. Note
When you configure a jitter probe the default codec value, g729a , is not nvgened in the running configuration.
-
TCP Connection--A TCP connection probe is sent to the target address. A target port number must be specified. A remote responder must be enabled if TCP messages are configured to use a port number other than TCP well-known port number 23.
-
UDP Echo--A UDP echo probe is sent to the target address. A target port number must be specified. A remote responder must be enabled on the target device, regardless of the configured port number.
PfR uses Cisco IOS IP Service Level Agreements (SLAs), a standard feature in Cisco IOS software, to command a border router to transmit an active probe to the target address. No explicit IP SLA configuration is required on the master controller or the border router. Support for IP SLAs is enabled by default when the PfR process is created. However, a remote responder must be enabled on the target device when configuring an active probe using jitter, UDP echo messages, or when configuring an active probe using TCP connection messages that are configured to use a port other than the TCP well-known port number 23. The remote responder is enabled by configuring the ip sla monitor responder global configuration command on the target device.
Note |
For external BGP (eBGP) peering sessions, the IP address of the eBGP peer must be reachable from the border router via a connected route in order for active probes to be generated. |
Examples
The following example shows the commands used to configure an active probe using an ICMP reply (ping) message. The 10.4.9.1 address is the target. No explicit configuration is required on the target device.
Router(config)# pfr master
Router(config-pfr-mc)# active-probe echo 10.4.9.1
The following example shows the commands used to configure an active probe using jitter messages. The 10.4.9.2 address is the target. The target port number must be specified when configuring this type of probe, and a remote responder must also be enabled on the target device. An optional codec value of g711alaw is specified to be used for MOS calculations.
Router(config)# pfr master
Router(config-pfr-mc)# active-probe jitter 10.4.9.2 target-port 1001 codec g711alaw
The following example shows the commands used to configure an active probe using a TCP connection message. The 10.4.9.3 address is the target. The target port number must be specified when configuring this type of probe.
Router(config)# pfr master
Router(config-pfr-mc)# active-probe tcp-conn 10.4.9.3 target-port 23
The following example shows the commands used to configure an active probe using UDP messages. The 10.4.9.4 address is the target. The target port number must be specified when configuring this type of probe, and a remote responder must also be enabled on the target device.
Router(config)# pfr master
Router(config-pfr-mc)# active-probe udp-echo 10.4.9.4 target-port 1001