Table Of Contents
Configuring NetFlow and NetFlow Data Export
Prerequisites for Configuring NetFlow and NetFlow Data Export
Restrictions for Configuring NetFlow and NetFlow Data Export
Information About Configuring NetFlow and NetFlow Data Export
NetFlow Cache Management and Data Export
NetFlow Export Format Versions 9, 8, 5, and 1
NetFlow Export Version Formats
NetFlow Export Packet Header Format
NetFlow Flow Record and Export Format Content Information
NetFlow Data Export Format Selection
NetFlow Version 9 Data Export Format
NetFlow Version 8 Data Export Format
NetFlow Version 5 Data Export Format
NetFlow Version 1 Data Export Format
Egress NetFlow Accounting Benefits: NetFlow Accounting Simplified
NetFlow Subinterface Support Benefits: Fine-Tuning Your Data Collection
NetFlow Multiple Export Destinations: Benefits
NetFlow on a Distributed VIP Interface
How to Configure NetFlow and NetFlow Data Export
Verify that NetFlow is Operational and View NetFlow Statistics
Configuring NetFlow Data Export Using the Version 9 Export Format
Verifying that NetFlow Data Export is Operational
Clearing NetFlow Statistics on the Router
Customizing the NetFlow Main Cache Parameters
NetFlow Cache Entry Management on a Routing Device
Configuration Examples for Configuring NetFlow and NetFlow Data Export
Configuring Egress NetFlow Accounting: Example
Configuring NetFlow Subinterface Support: Example
Configuring NetFlow Multiple Export Destinations: Example
Configuring NetFlow Version 5 Data Export: Example
Configuring NetFlow Version 1 Data Export: Example
Configure NetFlow for Analyzing PPPoE Session Traffic
Feature Information for Configuring NetFlow and NetFlow Data Export
Configuring NetFlow and NetFlow Data Export
This module contains information about and instructions for configuring NetFlow to capture and export network traffic data. NetFlow capture and export are performed independently on each internetworking device on which NetFlow is enabled. NetFlow need not be operational on each router in the network.
NetFlow is a Cisco IOS application that provides statistics on packets flowing through the router. NetFlow is emerging as a primary network accounting and security technology.
Module History
This module was first published on May 2, 2005, and last updated on September 5th, 2006.
Finding Feature Information in This Module
Your Cisco IOS software release may not support all features. To find information about feature support and configuration, use the "Feature Information for Configuring NetFlow and NetFlow Data Export" section.
Contents
•
Prerequisites for Configuring NetFlow and NetFlow Data Export
•
•
•
•
•
Prerequisites for Configuring NetFlow and NetFlow Data Export
Before you enable NetFlow you must:
•
•
•
Restrictions for Configuring NetFlow and NetFlow Data Export
NetFlow Data Capture
NetFlow consumes additional memory. If you have memory constraints, you might want to preset the size of the NetFlow cache so that it contains a smaller number of entries. The default cache size depends on the platform. For example, the default cache size for the Cisco 7500 router is 65536 (64K) entries.
Memory Impact
During times of heavy traffic, the additional flows can fill up the global flow hash table. If you need to increase the size of the global flow hash table, increase the memory of the router.
Cisco IOS Releases 12.2(14)S, 12.0(22)S, or 12.2(15)T
If your router is running a version of Cisco IOS prior to releases 12.2(14)S, 12.0(22)S, or 12.2(15)T the ip route-cache flow command is used to enable NetFlow on an interface.
If your router is running Cisco IOS release 12.2(14)S, 12.0(22)S, 12.2(15)T, or later the ip flow ingress command is used to enable NetFlow on an interface.
Egress NetFlow Accounting in Cisco IOS 12.3T Releases, 12.3(11)T or Later
The Egress NetFlow Accounting feature captures NetFlow statistics for IP traffic only. MPLS statistics are not captured. The MPLS Egress NetFlow Accounting feature can be used on a provider edge (PE) router to capture IP traffic flow information for egress IP packets that arrived at the router as MPLS packets and underwent label disposition.
Egress NetFlow accounting might adversely affect network performance because of the additional accounting-related computation that occurs in the traffic-forwarding path of the router.
Locally generated traffic (traffic that is generated by the router on which the Egress NetFlow Accounting feature is configured) is not counted as flow traffic for the Egress NetFlow Accounting feature.
Note
NetFlow Data Export
Restrictions for NetFlow Version 9 Data Export
•
•
•
Restrictions for NetFlow Version 8 Export Format
Version 8 export format is available only for aggregation caches, and it cannot be expanded to support new features.
Restrictions for NetFlow Version 5 Export Format
Version 5 export format is suitable only for the main cache, and it cannot be expanded to support new features.
Restrictions for NetFlow Version 1 Export Format
The Version 1 format was the initially released version. Do not use Version 1 format unless you are using a legacy collection system that requires it. Use Version 9 or Version 5 export format.
Information About Configuring NetFlow and NetFlow Data Export
This section contains information that you should understand before you configure NetFlow to analyze network traffic.
•
•
•
•
•
•
•
NetFlow Data Capture
NetFlow captures data from ingress (incoming) and egress (outgoing) packets. NetFlow gathers statistics for the following ingress IP packets:
•
•
•
•
NetFlow captures data for all egress (outgoing) packets through the use of the following features:
•
•
NetFlow Flows: Key Fields
A network flow is identified as a unidirectional stream of packets between a given source and destination—both are defined by a network-layer IP address and by transport-layer source and destination port numbers. Specifically, a flow is identified as the combination of the following key fields:
•
•
•
•
•
•
•
These seven key fields define a unique flow. If a packet has one key field different from another packet, it is considered to belong to another flow. A flow might contain other accounting fields (such as the AS number in the NetFlow export Version 5 flow format) that depend on the export record version that you configure. Flows are stored in the NetFlow cache.
NetFlow Cache Management and Data Export
The key components of NetFlow are the NetFlow cache or data source that stores IP flow information, and the NetFlow export or transport mechanism that sends NetFlow data to a network management collector, such as the NetFlow Collection Engine. NetFlow operates by creating a NetFlow cache entry (a flow record) for each active flow. A flow record is maintained within the NetFlow cache for each active flows. Each flow record in the NetFlow cache contains fields that can later be exported to a collection device, such as the NetFlow Collection Engine.
NetFlow is very efficient, the amount of export data being about 1.5 percent of the switched traffic in the router. NetFlow accounts for every packet (non-sampled mode) and provides a highly condensed and detailed view of all network traffic that entered the router or switch.
The key to NetFlow-enabled switching scalability and performance is highly intelligent flow cache management, especially for densely populated and busy edge routers handling large numbers of concurrent, short duration flows. The NetFlow cache management software contains a highly sophisticated set of algorithms for efficiently determining if a packet is part of an existing flow or should generate a new flow cache entry. The algorithms are also capable of dynamically updating per-flow accounting measurements residing in the NetFlow cache, and cache aging/flow expiration determination.
Rules for expiring NetFlow cache entries include:
•
•
•
•
Expired flows are grouped together into "NetFlow export" datagrams for export from the NetFlow- enabled device. NetFlow export datagrams can consist of up to 30 flow records for Version 5 or Version 9 flow export. NetFlow functionality is configured on a per-interface basis. To configure NetFlow export capabilities, you need to specify the IP address and application port number of the Cisco NetFlow or third-party flow collector. The flow collector is a device that provides NetFlow export data filtering and aggregation capabilities. Figure 1 shows an example of NetFlow data export from the main and aggregation caches to a collector.
Figure 1 NetFlow Data Export from the Main and Aggregation Caches
NetFlow Export Format Versions 9, 8, 5, and 1
Overview
NetFlow exports data in User Datagram Protocol (UDP) datagrams in one of the following formats: Version 9, Version 8, Version 7, Version 5, or Version 1.
•
•
•
•
Details
The following sections provide more detailed information on NetFlow Data Export Formats:
•
•
•
•
•
•
•
•
NetFlow Export Version Formats
For all export versions, the NetFlow export datagram consists of a header and a sequence of flow records. The header contains information such as sequence number, record count, and system uptime. The flow record contains flow information, for example IP addresses, ports, and routing information.
NetFlow Version 9 export format is the newest NetFlow export format. The distinguishing feature of the NetFlow Version 9 export format is that it is template based. Templates make the record format extensible. This feature allows future enhancements to NetFlow without requiring concurrent changes to the basic flow-record format.
The use of templates with the NetFlow Version 9 export format provides several other key benefits:
•
•
•
•
The work of the Internet Engineering Task Force (IETF) IP Information Export (IPFIX) Working Group (WG) and the IETF Pack Sampling (PSAMP) WG are based on the NetFlow Version 9 export format.
The Version 1 export format was the original format supported in the initial Cisco IOS software releases containing NetFlow functionality and is rarely used today. The Version 5 export format is a later enhancement that adds Border Gateway Protocol (BGP) autonomous system information and flow sequence numbers. Versions 2 through 4 and Version 6 export formats were either not released or are not supported. Version 8 export format is the NetFlow export format to use when you enable router-based NetFlow aggregation on Cisco IOS router platforms.
Figure 2 shows a typical datagram used for NetFlow fixed format export Versions 1, 5, 7, and 8.
Figure 2 Typical Datagram for NetFlow Fixed Format Export Versions 1, 5, 7, 8
NetFlow Export Packet Header Format
In all five export versions, the datagram consists of a header and one or more flow records. The first field of the header contains the version number of the export datagram. Typically, a receiving application that accepts any of the format versions allocates a buffer large enough for the largest possible datagram from any of the format versions and then uses the header to determine how to interpret the datagram. The second field in the header contains the number of records in the datagram (indicating the number of expired flows represented by this datagram). Datagram headers for NetFlow Export Versions 5, 8, and 9 also include a "sequence number" field used by NetFlow collectors to check for lost datagrams.
The NetFlow Version 9 export packet header format is shown in Figure 3.
Figure 3 NetFlow Version 9 Export Packet Header Format
Table 1 lists the NetFlow Version 9 export packet header field names and descriptions.
NetFlow Flow Record and Export Format Content Information
This section gives details about the Cisco export format flow record. Table 2 indicates which flow record format fields are available for Version 5, and 9. (Y indicates that the field is available. N indicates that the field is not available.)
Table 2 NetFlow Flow Record Format Fields for Format Versions 5, and 9
source IP address
Y
Y
destination IP address
Y
Y
source TCP/UDP application port
Y
Y
destination TCP/UDP application port
Y
Y
next hop router IP address
Y
Y
input physical interface index
Y
Y
output physical interface index
Y
Y
packet count for this flow
Y
Y
byte count for this flow
Y
Y
start of flow timestamp
Y
Y
end of flow timestamp
Y
Y
IP Protocol (for example, TCP=6; UDP=17)
Y
Y
Type of Service (ToS) byte
Y
Y
TCP Flags (cumulative OR of TCP flags)
Y
Y
source AS number
Y
Y
destination AS number
Y
Y
source subnet mask
Y
Y
destination subnet mask
Y
Y
flags (indicates, among other things, which flows are invalid)
Y
Y
Other flow fields1
N
Y
1 For a list of other flow fields available in Version 9 export format, see Figure 5.
Figure 4 is an example of the NetFlow Version 5 export record format, including the contents and description of byte locations. The terms in bold indicate values that were added for the Version 5 format.
Figure 4 NetFlow Version 5 Export Record Format
Table 3 shows the field names and descriptions for the NetFlow Version 5 export record format.
Figure 5 shows a typical flow record for the Version 9 export format. The NetFlow Version 9 export record format is different from the traditional NetFlow fixed format export record. In NetFlow Version 9, a template describes the NetFlow data and the flow set contains the actual data. This allows for flexible export. Detailed information about the fields currently in Version 9 and export format architecture are available in the NetFlow Version 9 Flow-Record Format document.
Figure 5 NetFlow Version 9 Export Packet Example
For all export versions, you specify a destination where NetFlow data export packets are sent, such as the workstation running NetFlow Collection Engine, either when the number of recently expired flows reaches a predetermined maximum, or every second—whichever occurs first. For a Version 1 datagram, up to 24 flows can be sent in a single UDP datagram of approximately 1200 bytes; for a Version 5 datagram, up to 30 flows can be sent in a single UDP datagram of approximately 1500 bytes.
For detailed information on the flow record formats, data types, and export data fields for Versions 1, 7, and 9 and platform-specific information when applicable, see Appendix 2 in the NetFlow Solutions Service Guide.
NetFlow Data Export Format Selection
NetFlow exports data in UDP datagrams in export format Version 9, 8, 5, or 1. Table 4 describes situations when you might select a particular NetFlow export format.
NetFlow Version 9 Data Export Format
The NetFlow Version 9 Export Format feature was introduced in Cisco IOS Release 12.0(24)S and was integrated into Cisco IOS Release 12.3(1) and Cisco IOS Release 12.2(18)S.
NetFlow Version 9 data export supports CEF switching, dCEF switching, and fast switching.
NetFlow Version 9 is a flexible and extensible means for transferring NetFlow records from a network node to a collector. NetFlow Version 9 has definable record types and is self-describing for easier NetFlow Collection Engine configuration.
Using Version 9 export, you define new formats on the router that you can send to the NetFlow Collection Engine (formerly called NetFlow FlowCollector) at set intervals. You enable the features that you want, and the field values corresponding to those features are sent to the NetFlow Collection Engine.
Third-party business partners who produce applications that provide NetFlow Collection Engine or display services for NetFlow do not need to recompile their applications each time a new NetFlow technology is added. Instead, with the NetFlow v9 Export Format feature, they can use an external data file that documents the known template formats and field types.
In NetFlow Version 9
•
•
•
•
NetFlow Version 9 Template-Based Flow Record Format
The main feature of NetFlow Version 9 export format is that it is template based. A template describes a NetFlow record format and attributes of the fields (such as type and length) within the record. The router assigns each template an ID, which is communicated to the NetFlow Collection Engine along with the template description. The template ID is used for all further communication from the router to the NetFlow Collection Engine.
NetFlow Version 9 Export Flow Records
The basic output of NetFlow is a flow record. In NetFlow Version 9 export format, a flow record follows the same sequence of fields as found in the template definition. The template to which NetFlow flow records belong is determined by the prefixing of the template ID to the group of NetFlow flow records that belong to a template. For a complete discussion of existing NetFlow flow-record formats, see the NetFlow Services Solutions Guide.
NetFlow Version 9 Export Packet
In NetFlow Version 9, an export packet consists of the packet header and flowsets. The packet header identifies the new version and provides other information. See Figure 3 for Version 9 export packet header details. Flowsets are of two types: template flowsets and data flowsets. The template flowset describes the fields that will be in the data flowsets (or flow records). Each data flowset contains the values or statistics of one or more flows with the same template ID. When the NetFlow Collection Engine receives a template flowset, it stores the flowset and export source address so that subsequent data flowsets that match the flowset ID and source combination are parsed according to the field definitions in the template flowset. Version 9 supports NetFlow Collection Engine Version 4.0. For an example of a Version 9 export packet, see Figure 5.
NetFlow Version 8 Data Export Format
The Version 8 data export format is the NetFlow export format used when the router-based NetFlow aggregation feature is enabled on Cisco IOS router platforms. The Version 8 format allows for export datagrams to contain a subset of the Version 5 export data that is based on the configured aggregation cache scheme. For example, a certain subset of the Version 5 export data is exported for the destination prefix aggregation scheme, and a different subset is exported for the source-prefix aggregation scheme.
The Version 8 export format was introduced in Cisco IOS 12.0(3)T for the Cisco IOS NetFlow Aggregation feature. An additional six aggregation schemes that also use Version 8 format were defined for the NetFlow ToS-Based Router Aggregation feature introduced in Cisco IOS 12.0(15)S and integrated into Cisco IOS Releases 12.2(4)T and 12.2(14)S. Refer to the "Configuring NetFlow Aggregation Caches" module for information on configuring Version 8 data export for aggregation caches.
The Version 8 datagram consists of a header with the version number (which is 8) and time stamp information, followed by one or more records corresponding to individual entries in the NetFlow cache.
Figure 6 displays the NetFlow Version 8 export packet header format.
Figure 6 NetFlow Version 8 Export Packet Header Format
Table 5 lists the NetFlow Version 8 export packet header field names and definitions.
NetFlow Version 5 Data Export Format
The Version 5 data export format adds support for Border Gateway Protocol (BGP) autonomous system information and flow sequence numbers.
Because NetFlow uses UDP to send export datagrams, datagrams can be lost. The Version 5 header format contains a flow sequence number to find out whether flow export information has been lost. The sequence number is equal to the sequence number of the previous datagram plus the number of flows in the previous datagram. After receiving a new datagram, the receiving application can subtract the expected sequence number from the sequence number in the header to get the number of missed flows.
All fields in Version 5 export format are in network byte order. Figure 7 shows the NetFlow Version 5 export packet header format.
Figure 7 NetFlow Version 5 Export Packet Header Format
Table 6 lists the NetFlow Version 5 export packet header field names and descriptions.
Table 7 describes the Version 5 export format header network byte order.
Table 8 lists the byte definitions for the Version 5 flow record format.
NetFlow Version 1 Data Export Format
The NetFlow Version 1 data export format was the format supported in the initial Cisco IOS software releases containing NetFlow functionality. It is rarely used today. Do not use the Version 1 export format unless the legacy collection system you are using requires it. Use either the Version 9 export format or the Version 5 export format.
Figure 8 shows the NetFlow Version 1 export packet header format.
Figure 8 Version 1 Export Packet Header Format
Table 9 lists the NetFlow Version 1 export packet header field names and descriptions.
Egress NetFlow Accounting Benefits: NetFlow Accounting Simplified
The Egress NetFlow Accounting feature can simplify NetFlow configuration. The following example shows how.
In Figure 9 and Figure 10 both incoming and outgoing (ingress and egress) flow statistics are required for the server. The server is attached to Router B. The "cloud" in the figure represents the core of the network and includes Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs).
All traffic denoted by the arrows must be accounted for. The solid arrows represent IP traffic and the dotted arrows represent MPLS VPNs.
Figure 9 shows how the flow traffic was tracked before the introduction of the Egress NetFlow Accounting feature. Figure 10 shows how the flow traffic is tracked after the introduction of the Egress NetFlow Accounting feature. The Egress NetFlow Accounting feature simplifies configuration tasks and makes it easier for you to collect and track incoming and outgoing flow statistics for the server in this example.
Since only ingress flows could be tracked before the Egress NetFlow Accounting feature was introduced, the following NetFlow configurations had to be implemented for the tracking of ingress and egress flows from Router B:
•
•
•
•
Figure 9 Ingress-Only NetFlow Example
A configuration such as the one used in Figure 9 requires that NetFlow statistics from three separate routers be added together to obtain the flow statistics for the server.
In comparison, the example in Figure 10 shows NetFlow, the Egress NetFlow Accounting feature, and the MPLS Egress NetFlow Accounting feature being used to capture ingress and egress flow statistics for Router B, thus obtaining the required flow statistics for the server.
In Figure 10, the following NetFlow configurations are applied to Router B:
•
•
•
•
After NetFlow is configured on Router B, you can display all NetFlow statistics for the server by entering the show ip cache flow command or the show ip cache verbose flow command for Router B.
Figure 10 Egress NetFlow Accounting Example
.
NetFlow Subinterface Support Benefits: Fine-Tuning Your Data Collection
You can configure NetFlow on a per-subinterface basis. If your network contains thousands of subinterfaces and you want to collect export records from only a few subinterfaces, you can do that. The result is lower bandwidth requirements for NetFlow data export and reduced platform requirements for NetFlow data-collection devices.
The configuration of NetFlow on selected subinterfaces provides the following benefits:
•
•
NetFlow Multiple Export Destinations: Benefits
The NetFlow Multiple Export Destinations feature enables configuration of multiple destinations for the NetFlow data. With this feature enabled, two identical streams of NetFlow data are sent to the destination host. Currently, the maximum number of export destinations allowed is two.
The NetFlow Multiple Export Destinations feature improves the chances of receiving complete NetFlow data because it provides redundant streams of data. Because the same export data is sent to more than one NetFlow collector, fewer packets are lost.
NetFlow on a Distributed VIP Interface
On a Cisco 7500 series router with an Route Switch Processor (RSP) and with VIP controllers, the VIP hardware can be configured to switch packets received by the VIP interfaces with no per-packet intervention on the part of the RSP. This process is called distributed switching. When VIP distributed switching is enabled, the input VIP interface switches IP packets instead of forwarding them to the RSP for switching. Distributed switching decreases the demand on the RSP. VIP interfaces with distributed switching enabled can be configured for NetFlow.
How to Configure NetFlow and NetFlow Data Export
This section contains instructions for configuring NetFlow to capture and export network traffic data. Perform the following tasks to configure NetFlow to capture and export network traffic data:
•
•
•
•
•
•
Configure NetFlow
Perform the steps in this required task to enable NetFlow.
SUMMARY STEPS
1.
2.
3.
4.
5.
6.
7.
DETAILED STEPS
Step 1
enable
Example:Router> enable
(Required) Enables privileged EXEC mode.
•
Step 2
configure terminal
Example:Router# configure terminal
(Required) Enters global configuration mode.
Step 3
interface interface-type interface-number
Example:Router(config)# interface ethernet 0/0
(Required) Specifies the interface that you want to enable NetFlow on and enters interface configuration mode.
Step 4
ip flow {ingress | egress}
Example:Router(config-if)# ip flow ingress
or
Example:Router(config-if)# ip flow egress
(Required) Enables NetFlow on the interface.
•
•
This is the Egress NetFlow Accounting feature that is described in the "Egress NetFlow Accounting Benefits: NetFlow Accounting Simplified" section.
Step 5
exit
Example:Router(config-if)# exit
(Optional) Exits interface configuration mode and returns to global configuration mode.
Note
Step 6
Repeat Steps 3 through 5 to enable NetFlow on other interfaces
(Optional) —
Step 7
end
Example:Router(config-if)# end
(Required) Exits the current configuration mode and returns to privileged EXEC mode.
Verify that NetFlow is Operational and View NetFlow Statistics
Perform the steps in this optional task to verify that NetFlow is operational and to view the NetFlow statistics.
SUMMARY STEPS
1.
2.
3.
DETAILED STEPS
Step 1
Use this command to display the NetFlow configuration for an interface. The following is sample output from this command:
Router# show ip flow interfaceEthernet0/0ip flow ingressRouter#Step 2
Use this command to verify that NetFlow is operational, and to display a summary of the NetFlow statistics. The following is sample output from this command:
Router# show ip cache flowIP packet size distribution (1103746 total packets):1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480.249 .694 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000512 544 576 1024 1536 2048 2560 3072 3584 4096 4608.000 .000 .027 .000 .027 .000 .000 .000 .000 .000 .000IP Flow Switching Cache, 278544 bytes35 active, 4061 inactive, 980 added2921778 ager polls, 0 flow alloc failuresActive flows timeout in 30 minutesInactive flows timeout in 15 secondsIP Sub Flow Cache, 21640 bytes0 active, 1024 inactive, 0 added, 0 added to flow0 alloc failures, 0 force free1 chunk, 1 chunk addedlast clearing of statistics neverProtocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)-------- Flows /Sec /Flow /Pkt /Sec /Flow /FlowTCP-FTP 108 0.0 1133 40 2.4 1799.6 0.9TCP-FTPD 108 0.0 1133 40 2.4 1799.6 0.9TCP-WWW 54 0.0 1133 40 1.2 1799.6 0.8TCP-SMTP 54 0.0 1133 40 1.2 1799.6 0.8TCP-BGP 27 0.0 1133 40 0.6 1799.6 0.7TCP-NNTP 27 0.0 1133 40 0.6 1799.6 0.7TCP-other 297 0.0 1133 40 6.8 1799.7 0.8UDP-TFTP 27 0.0 1133 28 0.6 1799.6 1.0UDP-other 108 0.0 1417 28 3.1 1799.6 0.9ICMP 135 0.0 1133 427 3.1 1799.6 0.8Total: 945 0.0 1166 91 22.4 1799.6 0.8SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP PktsEt0/0 192.168.67.6 Et1/0.1 172.16.10.200 01 0000 0C01 51Et0/0 10.10.18.1 Null 172.16.11.5 11 0043 0043 51Et0/0 10.10.18.1 Null 172.16.11.5 11 0045 0045 51Et0/0 10.234.53.1 Et1/0.1 172.16.10.2 01 0000 0800 51Et0/0 10.10.19.1 Null 172.16.11.6 11 0044 0044 51Et0/0 10.10.19.1 Null 172.16.11.6 11 00A2 00A2 51Et0/0 192.168.87.200 Et1/0.1 172.16.10.2 06 0014 0014 50Et0/0 192.168.87.200 Et1/0.1 172.16.10.2 06 0015 0015 52...Et0/0 172.16.1.84 Et1/0.1 172.16.10.19 06 0087 0087 50Et0/0 172.16.1.84 Et1/0.1 172.16.10.19 06 0050 0050 51Et0/0 172.16.1.85 Et1/0.1 172.16.10.20 06 0089 0089 49Et0/0 172.16.1.85 Et1/0.1 172.16.10.20 06 0050 0050 50Et0/0 10.251.10.1 Et1/0.1 172.16.10.2 01 0000 0800 51Et0/0 10.162.37.71 Null 172.16.11.3 06 027C 027C 49Router#Step 3
Use this command to verify that NetFlow is operational and to display a detailed summary of the NetFlow statistics. The following is sample output from this command:
Router# show ip cache verbose flowIP packet size distribution (1130681 total packets):1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480.249 .694 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000512 544 576 1024 1536 2048 2560 3072 3584 4096 4608.000 .000 .027 .000 .027 .000 .000 .000 .000 .000 .000IP Flow Switching Cache, 278544 bytes35 active, 4061 inactive, 980 added2992518 ager polls, 0 flow alloc failuresActive flows timeout in 30 minutesInactive flows timeout in 15 secondsIP Sub Flow Cache, 21640 bytes0 active, 1024 inactive, 0 added, 0 added to flow0 alloc failures, 0 force free1 chunk, 1 chunk addedlast clearing of statistics neverProtocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)-------- Flows /Sec /Flow /Pkt /Sec /Flow /FlowTCP-FTP 108 0.0 1133 40 2.4 1799.6 0.9TCP-FTPD 108 0.0 1133 40 2.4 1799.6 0.9TCP-WWW 54 0.0 1133 40 1.2 1799.6 0.8TCP-SMTP 54 0.0 1133 40 1.2 1799.6 0.8TCP-BGP 27 0.0 1133 40 0.6 1799.6 0.7TCP-NNTP 27 0.0 1133 40 0.6 1799.6 0.7TCP-other 297 0.0 1133 40 6.6 1799.7 0.8UDP-TFTP 27 0.0 1133 28 0.6 1799.6 1.0UDP-other 108 0.0 1417 28 3.0 1799.6 0.9ICMP 135 0.0 1133 427 3.0 1799.6 0.8Total: 945 0.0 1166 91 21.9 1799.6 0.8SrcIf SrcIPaddress DstIf DstIPaddress Pr TOS Flgs PktsPort Msk AS Port Msk AS NextHop B/Pk ActiveEt0/0 192.168.67.6 Et1/0.1 172.16.10.200 01 00 10 7990000 /0 0 0C01 /0 0 0.0.0.0 28 1258.1Et0/0 10.10.18.1 Null 172.16.11.5 11 00 10 7990043 /0 0 0043 /0 0 0.0.0.0 28 1258.0Et0/0 10.10.18.1 Null 172.16.11.5 11 00 10 7990045 /0 0 0045 /0 0 0.0.0.0 28 1258.0Et0/0 10.234.53.1 Et1/0.1 172.16.10.2 01 00 10 7990000 /0 0 0800 /0 0 0.0.0.0 28 1258.1Et0/0 10.10.19.1 Null 172.16.11.6 11 00 10 7990044 /0 0 0044 /0 0 0.0.0.0 28 1258.1...Et0/0 172.16.1.84 Et1/0.1 172.16.10.19 06 00 00 7990087 /0 0 0087 /0 0 0.0.0.0 40 1258.1Et0/0 172.16.1.84 Et1/0.1 172.16.10.19 06 00 00 7990050 /0 0 0050 /0 0 0.0.0.0 40 1258.0Et0/0 172.16.1.85 Et1/0.1 172.16.10.20 06 00 00 7980089 /0 0 0089 /0 0 0.0.0.0 40 1256.5Et0/0 172.16.1.85 Et1/0.1 172.16.10.20 06 00 00 7990050 /0 0 0050 /0 0 0.0.0.0 40 1258.0Et0/0 10.251.10.1 Et1/0.1 172.16.10.2 01 00 10 7990000 /0 0 0800 /0 0 0.0.0.0 1500 1258.1Et0/0 10.162.37.71 Null 172.16.11.3 06 00 00 798027C /0 0 027C /0 0 0.0.0.0 40 1256.4Router#Configuring NetFlow Data Export Using the Version 9 Export Format
Perform the steps in this optional task to configure NetFlow Data Export using the Version 9 export format, perform the steps in this section. This section contains the following subsections:
Prerequisites
This task does not include the steps for configuring NetFlow. You must configure NetFlow by enabling it on at least one interface in the router in order to export traffic data with NetFlow Data Export. Refer to the "Configure NetFlow" section for information about configuring NetFlow.
SUMMARY STEPS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
