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Flexible Netflow Configuration Guide, Cisco IOS Release 12.4T
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Using Flexible NetFlow Top N Talkers to Analyze Network Traffic
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Contents
Using Flexible NetFlow Top N Talkers to Analyze Network TrafficLast Updated: September 4, 2012
This document contains information about and instructions for using the Flexible NetFlow--Top N Talkers Support feature. The Flexible NetFlow--Top N Talkers Support feature helps you analyze the large amount of data that Flexible NetFlow captures from the traffic in your network by providing the ability to filter, aggregate, and sort the data in the Flexible NetFlow cache as you display it. When you are sorting and displaying the data in the cache, you can limit the display output to a specific number of entries with the highest values (Top N Talkers) for traffic volume, packet counters, and so on. The Flexible NetFlow--Top N Talkers Support feature facilitates real-time traffic analysis by requiring only the use of show commands, which can be entered in many different variations using the available keywords and arguments to meet your traffic data analysis requirements. NetFlow is a Cisco IOS technology that provides statistics on packets flowing through the router. NetFlow is the standard for acquiring IP operational data from IP networks. NetFlow provides data to support network and security monitoring, network planning, traffic analysis, and IP accounting. Flexible NetFlow improves on original NetFlow by adding the capability to customize the traffic analysis parameters for your specific requirements. Flexible NetFlow facilitates the creation of more complex configurations for traffic analysis and data export through the use of reusable configuration components.
Finding Feature InformationYour software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required. Prerequisites for Flexible NetFlow Top N Talkers
No configuration tasks are associated with the Flexible NetFlow--Top N Talkers Support feature. Therefore, in order for you to use the Flexible NetFlow--Top N Talkers Support feature, traffic analysis with Flexible NetFlow must already be configured about the networking device. Information About Flexible NetFlow Top N Talkers
Flexible NetFlow Data Flow FilteringThe flow filtering function of the Flexible NetFlow--Top N Talkers Support feature filters the flow data in a flow monitor cache based on the criteria that you specify, and displays the data. The flow filtering function of the Flexible NetFlow--Top N Talkers Support feature is provided by the show flow monitor cache filter command. For more information on the show flow monitor cache filter command, refer to the Cisco IOS Flexible NetFlow Command Reference. Flexible NetFlow Data Flow AggregationFlow aggregation using the show flow monitor cache aggregate command allows you to dynamically view the flow information in a cache using a different flow record than the cache was originally created from. Only the fields in the cache will be available for the aggregated flows. The flow aggregation function of the Flexible NetFlow--Top N Talkers Support feature is provided by the show flow monitor cache aggregate command. For more information on the show flow monitor cache aggregate command, refer to the Cisco IOS Flexible NetFlow Command Reference. Flow Sorting and Top N TalkersThe flow sorting function of the Flexible NetFlow--Top N Talkers Support feature sorts flow data from the Flexible NetFlow cache based on the criteria that you specify and displays the data. You can also use the flow sorting function of the Flexible NetFlow--Top N Talkers Support feature to limit the display output to a specific number of entries (top n talkers, where n is the number or talkers to display) by using the top keyword. The flow sorting and Top N Talkers function of the Flexible NetFlow--Top N Talkers Support feature is provided by the show flow monitor cache sort command. For more information on the show flow monitor cache sort command, refer to the Cisco IOS Flexible NetFlow Command Reference. Documented Flexible NetFlow Top N Talkers Command Names and Actual SyntaxThe three commands that make up the Flexible NetFlow--Top N Talkers Support feature are documented using the Cisco documentation convention of using the initial words in the CLI syntax, omitting a subsequent words in the CLI syntax, and using a word in the CLI syntax that follows the omitted words. Therefore the syntax that you use for entering the commands is different from the actual documented command name. The table below shows the documented commands names and the actual command CLI syntax. The monitor-name argument is the name of a flow monitor that was previously configured.
Combined Use of Flow Filtering and Flow Aggregation and Flow Sorting with Top N TalkersAlthough each of the show commands that make up the Flexible NetFlow--Top N Talkers Support feature can be used individually for traffic analysis, they provide much greater analytical capabilities when they are used together. When you use any combination of the three show commands, you enter only the common prefix of show flow monitor monitor-name cachefollowed by filter, aggregation, sort, and the arguments and keywords available for filter, aggregation, sort, as required. For example, show flow monitor monitor-name cache filter options aggregation options sort options where options is any permissible combination of arguments and keywords. See the Configuration Examples for Flexible NetFlow Top N Talkers for more information. Memory and Performance Impact of Top N TalkersThe Flexible NetFlow--Top N Talkers Support feature can use a large number of CPU cycles and possibly also system memory for a short time. However, because the Flexible NetFlow--Top N Talkers Support feature uses only show commands, the CPU usage should be run at a low priority because no real-time data processing is involved. The memory usage can be mitigated by using a larger granularity of aggregation, or no aggregation at all. How to Analyze Network Traffic Using Flexible NetFlow Top N Talkers
Filtering Flow Data from the Flexible NetFlow CacheThis task shows you how to use the show flow monitor cache filter command with a regular expression to filter the flow monitor cache data, and display the results. For more information on regular expressions and the show flow monitor cache filter command, refer to the Cisco IOS Flexible NetFlow Command Reference. To filter the flow monitor cache data using a regular expression and display the results, perform the following task. DETAILED STEPS
Aggregating Flow Data from the Flexible NetFlow CacheThis task shows you how to use the show flow monitor cache aggregate command to aggregate the flow monitor cache data with a different record than the cache was created with, and display the results. For more information on the show flow monitor cache aggregate command, refer to the Cisco IOS Flexible NetFlow Command Reference. To aggregate the flow monitor cache data and display the results, perform the following task. DETAILED STEPS
Sorting Flow Data from the Flexible NetFlow CacheThis task shows you how to use the show flow monitor cache sort command to sort the flow monitor cache data, and display the results. For more information on the show flow monitor cache sort command, refer to the Cisco IOS Flexible NetFlow Command Reference. To sort the flow monitor cache data and display the results, perform the following task. DETAILED STEPS Displaying the Top N Talkers with Sorted Flow DataThis task shows you how to use the show flow monitor cache sort command to sort the flow monitor cache data, and to limit the display results to a specific number of high volume flows. For more information on the show flow monitor cache sort command, refer to the Cisco IOS Flexible NetFlow Command Reference. To sort the flow monitor cache data and limit the display output using to a specific number of high volume flows, perform the following task. DETAILED STEPS
Configuration Examples for Flexible NetFlow Top N Talkers
Example Displaying the Top Talkers with Filtered and Aggregated and Sorted Flow DataThe following example combines filtering, aggregation, collecting additional field data, sorting the flow monitor cache data, and limiting the display output to a specific number of high volume flows (top talkers).
Router# show flow monitor FLOW-MONITOR-1 cache filter ipv4 protocol regexp (1|6) aggregate ipv4 destination address collect ipv4 protocol sort counter bytes top 4
Processed 26 flows
Matched 26 flows
Aggregated to 13 flows
Showing the top 4 flows
IPV4 DST ADDR flows bytes pkts
=============== ========== ========== ==========
172.16.10.2 12 1358370 6708
172.16.10.19 2 44640 1116
172.16.10.20 2 44640 1116
172.16.10.4 1 22360 559
The following example combines filtering using a regular expression, aggregation using a predefined record, sorting the flow monitor cache data, limiting the display output to a specific number of high volume flows (top talkers), and displaying the output in record format.
Router# show flow monitor FLOW-MONITOR-1 cache filter ipv4 source address regexp 10.* aggregate record netflow ipv4 protocol-port sort transport destination-port top 5 format record
Processed 26 flows
Matched 15 flows
Aggregated to 10 flows
Showing the top 5 flows
TRNS SOURCE PORT: 0
TRNS DESTINATION PORT: 0
FLOW DIRECTION: Input
IP PROTOCOL: 1
counter flows: 1
counter bytes: 387800
counter packets: 700
timestamp first: 17:12:30.712
timestamp last: 17:30:52.936
TRNS SOURCE PORT: 20
TRNS DESTINATION PORT: 20
FLOW DIRECTION: Input
IP PROTOCOL: 6
counter flows: 2
counter bytes: 56000
counter packets: 1400
timestamp first: 17:12:29.532
timestamp last: 17:30:53.148
TRNS SOURCE PORT: 21
TRNS DESTINATION PORT: 21
FLOW DIRECTION: Input
IP PROTOCOL: 6
counter flows: 2
counter bytes: 56000
counter packets: 1400
timestamp first: 17:12:29.572
timestamp last: 17:30:53.196
TRNS SOURCE PORT: 22
TRNS DESTINATION PORT: 22
FLOW DIRECTION: Input
IP PROTOCOL: 6
counter flows: 1
counter bytes: 28000
counter packets: 700
timestamp first: 17:12:29.912
timestamp last: 17:30:52.168
TRNS SOURCE PORT: 25
TRNS DESTINATION PORT: 25
FLOW DIRECTION: Input
IP PROTOCOL: 6
counter flows: 2
counter bytes: 56000
counter packets: 1400
timestamp first: 17:12:29.692
timestamp last: 17:30:51.968
Example Filtering Using Multiple Filtering CriteriaThe following example filters the cache data on the IPv4 destination address and the destination port:
Router# show flow monitor FLOW-MONITOR-1 cache filter ipv4 destination address regexp 172.16.10* transport destination-port 21
Cache type: Normal
Cache size: 4096
Current entries: 26
High Watermark: 26
Flows added: 241
Flows aged: 215
- Active timeout ( 1800 secs) 50
- Inactive timeout ( 15 secs) 165
- Event aged 0
- Watermark aged 0
- Emergency aged 0
IPV4 SOURCE ADDRESS: 10.10.10.2
IPV4 DESTINATION ADDRESS: 172.16.10.2
TRNS SOURCE PORT: 21
TRNS DESTINATION PORT: 21
INTERFACE INPUT: Et0/0.1
FLOW SAMPLER ID: 0
IP TOS: 0x00
IP PROTOCOL: 6
ip source as: 0
ip destination as: 0
ipv4 next hop address: 172.16.7.2
ipv4 source mask: /0
ipv4 destination mask: /24
tcp flags: 0x00
interface output: Et1/0.1
counter bytes: 17200
counter packets: 430
timestamp first: 17:03:58.071
timestamp last: 17:15:14.615
IPV4 SOURCE ADDRESS: 172.30.231.193
IPV4 DESTINATION ADDRESS: 172.16.10.2
TRNS SOURCE PORT: 21
TRNS DESTINATION PORT: 21
INTERFACE INPUT: Et0/0.1
FLOW SAMPLER ID: 0
IP TOS: 0x00
IP PROTOCOL: 6
ip source as: 0
ip destination as: 0
ipv4 next hop address: 172.16.7.2
ipv4 source mask: /0
ipv4 destination mask: /24
tcp flags: 0x00
interface output: Et1/0.1
counter bytes: 17160
counter packets: 429
timestamp first: 17:03:59.963
timestamp last: 17:15:14.887
Matched 2 flows
Example Aggregation Using Multiple Aggregation CriteriaThe following example aggregates the flow monitor cache data on the destination and source IPv4 addresses:
Router# show flow monitor FLOW-MONITOR-1 cache aggregate ipv4 destination address ipv4 source address
Processed 26 flows
Aggregated to 17 flows
IPV4 SRC ADDR IPV4 DST ADDR flows bytes pkts
=============== =============== ========== ========== ==========
10.251.10.1 172.16.10.2 2 1400828 1364
192.168.67.6 172.16.10.200 1 19096 682
10.234.53.1 172.16.10.2 3 73656 2046
172.30.231.193 172.16.10.2 3 73616 2045
10.10.10.2 172.16.10.2 2 54560 1364
192.168.87.200 172.16.10.2 2 54560 1364
10.10.10.4 172.16.10.4 1 27280 682
10.10.11.1 172.16.10.5 1 27280 682
10.10.11.2 172.16.10.6 1 27280 682
10.10.11.3 172.16.10.7 1 27280 682
10.10.11.4 172.16.10.8 1 27280 682
10.1.1.1 172.16.10.9 1 27280 682
10.1.1.2 172.16.10.10 1 27280 682
10.1.1.3 172.16.10.11 1 27280 682
172.16.1.84 172.16.10.19 2 54520 1363
172.16.1.85 172.16.10.20 2 54520 1363
172.16.6.1 224.0.0.9 1 52 1
Additional ReferencesRelated Documents
MIBsTechnical Assistance
Feature Information for Flexible NetFlow Top N TalkersThe following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R) Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental. © 2012 Cisco Systems, Inc. All rights reserved.
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