- Index
- Preface
- Product Overview
- Command-Line Interfaces
- Configuring the Switch for the First Time
- Configuring Interfaces
- Checking Port Status and Connectivity
- Configuring Supervisor Engine Redundancy using RPR and SSO
- Environmental Monitoring and Power Management
- Configuring Power over Ethernet
- Managing a Network of Switches
- Understanding and Configuring VLANs
- Configuring Dynamic VLAN Membership
- Configuring Layer 2 Ethernet Interfaces
- Configuring SmartPort Macros
- Understanding and Configuring STP
- Configuring STP Features
- Understanding and Configuring Multiple Spanning Trees
- Understanding and Configuring EtherChannel
- Configuring IGMP Snooping and Filtering
- Configuring 802.1Q and Layer 2 Protocol Tunneling
- Understanding and Configuring CDP
- Configuring UDLD
- Configuring Unidirectional Ethernet
- Configuring Layer 3 Interfaces
- Configuring Cisco Express Forwarding
- Understanding and Configuring IP Multicast
- Configuring Policy-Based Routing
- Understanding and Configuring VTP
- Configuring VRF-lite
- Configuring QoS
- Configuring Voice Interfaces
- Understanding and Configuring 802.1X Port-Based Authentication
- Configuring Port Security
- Configuring DHCP Snooping and IP Source Guard
- Understanding and Configuring Dynamic ARP Inspection
- Configuring Network Security with ACLs
- Configuring Private VLANs
- Port Unicast and Multicast Flood Blocking
- Configuring Port-Based Traffic Control
- Configuring SPAN and RSPAN
- Configuring NetFlow Statistics Collection
- Acronyms
- Overview of NetFlow Statistics Collection
- Information Derived from Hardware
- Information Derived from Software
- Determining the Input and Output Interface and AS Numbers
- Feature Interaction of Netflow Statistics with UBRL and Microflow Policing
- VLAN Statistics
Configuring NetFlow Statistics Collection
This chapter describes how to configure NetFlow Statistics on the Catalyst 4500 series switches. It also provides guidelines, procedures, and configuration examples.
Note 
To use the NetFlow feature, you must have the Supervisor Engine V-10GE (the functionality is embedded in the supervisor engine), or the NetFlow Services Card (WS-F4531) and either a Supervisor Engine IV or a Supervisor Engine V.
Note For complete syntax and usage information for the commands used in this chapter, refer to the Catalyst 4500 Series Switch Cisco IOS Command Reference and related publications at
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/index.htm. Refer to the NetFlow Solutions Guide for more detailed information on NetFlow usage and management.
The following topics are included:
•Overview of NetFlow Statistics Collection
•Configuring NetFlow Statistics Collection
•NetFlow Statistics Collection Configuration Example
•NetFlow Configuration Examples
Overview of NetFlow Statistics Collection
A network flow is defined as a unidirectional stream of packets between a given source and destination —both defined by a network-layer IP address and transport-layer port number. Specifically, a flow is identified as the combination of the following fields: source IP address, destination IP address, source port number, destination port number, protocol type, type of service, and input interface.
NetFlow Statistics is a global traffic monitoring feature that allows flow-level monitoring of all IPv4-routed traffic through the switch using NetFlow Data Export (NDE). Collected statistics can be exported to an external device (NetFlow Collector/Analyzer) for further processing. Network planners can selectively enable NetFlow Statistics (and NDE) on a per-device basis to gain traffic performance, control, or accounting benefits in specific network locations.
NetFlow exports flow information in UDP datagrams in one of two formats. The version 1 format was the initial released version, and version 5 is a later enhancement to add Border Gateway Protocol (BGP) autonomous system (AS) information and flow sequence numbers. In version 1 and version 5 format, 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.
This section contains the following subsections:
•Information Derived from Hardware
•Information Derived from Hardware
•Information Derived from Software
•Determining the Input and Output Interface and AS Numbers
•Feature Interaction of Netflow Statistics with UBRL and Microflow Policing
NDE Versions
The Catalyst 4500 series switch supports NDE versions 1 and 5 for the captured statistics. NetFlow aggregation requires NDE version 8.
Depending on the current flow mask, some fields in the flow records might not have values. Unsupported fields contain a zero (0).
The following tables describe the supported fields for NDE version 5:
•Table 40-1—Version 5 header format
•Table 40-2—Version 5 flow record format
|
|
|
|
|
|||||
|---|---|---|---|---|---|---|---|---|
|
|
|
Source |
Source Interface |
|
Interface |
|||
0-3 |
srcaddr |
Source IP address |
|
|
|
|
|
|
4-7 |
dstaddr |
Destination IP address |
|
|
|
|
|
|
8-11 |
nexthop |
Next hop router's IP address |
|
|
|
|
|
|
12-13 |
input |
Ingress interface SNMP ifIndex |
|
|
||||
14-15 |
output |
Egress interface SNMP ifIndex |
|
|
|
|
|
|
16-19 |
dPkts |
Packets in the flow |
|
|
|
|
|
|
20-23 |
dOctets |
Octets (bytes) in the flow |
|
|
|
|
|
|
24-27 |
first |
SysUptime at start of the flow |
|
|
|
|
|
|
28-31 |
last |
SysUptime at the time the last packet of the flow was received |
|
|
|
|
|
|
32-33 |
srcport |
Layer 4 source port number or equivalent |
|
|
||||
34-35 |
dstport |
Layer 4 destination port number or equivalent |
|
|
||||
36 |
pad1 |
Unused (zero) byte |
||||||
37 |
tcp_flags |
Cumulative OR of TCP flags |
||||||
38 |
prot |
Layer 4 protocol (for example, 6=TCP, 17=UDP) |
|
|
||||
39 |
tos |
IP type-of-service byte |
||||||
40-41 |
src_as |
Autonomous system number of the source, either origin or peer |
|
|
|
|
|
|
42-43 |
dst_as |
Autonomous system number of the destination, either origin or peer |
|
|
|
|
|
|
44-45 |
src_mask |
Source address prefix mask bits |
|
|
|
|
|
|
46-47 |
dst_mask |
Destination address prefix mask bits |
|
|
|
|
|
|
48 |
pad2 |
Pad 2 is unused (zero) bytes |
||||||
1 With the destination flow mask, the "Next hop router's IP address" field and the "Output interface's SNMP ifIndex" field might not contain information that is accurate for all flows. 2 In PFC3BXL or PFC3B mode, ICMP traffic contains the ICMP code and type values. |
Information Derived from Hardware
Information available in a typical NetFlow record from hardware includes the following:
•the packet and byte counts
•start and end timestamps
•source and destination IP addresses
•IP protocol
•source and destination port numbers.
Information Derived from Software
The software infers the following fields:
•Input and output identifiers
•Routing information, including next-hop address, origin and peer AS, source and destination prefix mask
Determining the Input and Output Interface and AS Numbers
The following topics are discussed:
•Determining the Inferred Fields
•Determining the Output Interface and Output Related Inferred Fields
•Determining the Input Interface and Input Related Inferred Fields
Determining the Inferred Fields
The Catalyst 4500 series switch collects netflow flows in hardware. The hardware collects a sub-set of all the netflow flow fields. The rest of the fields are then filled in by the software when the software examines the routing state.
The Netflow Services Card does not provide enough information to accurately and consistently determine the input interface, output interface and other routing information associated with NetFlow Flows. The Catalyst 4500 series switch has a software mechanism to largely compensate for this. The mechanism is described in the next paragraph.
Determining the Output Interface and Output Related Inferred Fields
Software determines the output interface information by looking up the Forwarding Information Base (FIB) entry in the default FIB table (based on the destination IP address). From this FIB entry, the software gains access to the destination AS number for this destination IP address, as well as the appropriate adjacency that stores the interface information. Therefore, the output interface is based solely on the destination IP address. If load balancing is enabled on the switch, the load balancing hash, instead of looking at the adjacency in the FIB entry, will be applied to access the appropriate FIB path and access the appropriate adjacency. Although this process will typically yield correct results, a potential inaccuracy can occur when using a PBR that shares IP addresses with the default FIB table. Under these circumstances, there would then be multiple FIB table entries and associated adjacencies for the same destination IP address.
Determining the Input Interface and Input Related Inferred Fields
Similarly, the input interface and the source AS number for the source IP address are determined by looking up the FIB entry in the default FIB table based on the source IP address. Therefore, the input interface is based solely on the source IP address and a reverse lookup is done to determine to which interface a packet with this IP destination address needs to be routed. This process assumes that the forwarding paths are symmetrical. However, if this process yields multiple input interfaces, a deterministic algorithm will be applied to pick one of them the one with the lowest IP address. Although this process typically yields correct values, there are scenarios where the values are inaccurate:
•If load balancing is being applied by an upstream adjacent switch, one input interface must be chosen arbitrarily out of the multiple input interfaces available. This action is necessary because the input interface that would be used depends on the type of load balancing algorithm being deployed by the adjacent upstream switch. It is not always feasible to know the algorithm. Therefore, all flow statistics will be attributed to one input interface. Software selects the interface with the lowest IP subnet number.
•In an asymmetric routing scheme, where the traffic for an IP subnet might be received on an interface that is different from the interface where packets are sent to this IP subnet, the inferences noted previously for selecting an input interface, based on a reverse lookup, would be incorrect and cannot be verified.
•If PBR or VRF is enabled on the switch and the flow is destined to an address that resides in the PBR or VRF range or is sourced from an address that resides in the PBR or VRF range, the information will be incorrect. In this case, the input and output interface will most likely point to the default route (if configured) or will have no value at all (NULL)
• If VRF is enabled on the switch on some interfaces and the flow is sourced from a VRF interface, the information will be incorrect. In this case, the input and output interface will most likely point to the default route (if configured) or will have no value (NULL).
Note The Supervisor Engine V-10GE does a better job at this by providing the input interface information via hardware. Having this information greatly improves the accuracy of the inferred fields.
Feature Interaction of Netflow Statistics with UBRL and Microflow Policing
On systems with Supervisor Engine V-10GE, there is a feature interaction between Netflow Statistics and UBRL (User Based Rate Limiting). As part of correctly configuring UBRL on a given interface, the class-map must specify a flow-mask. In turn, this flow mask is used to create hardware-based netflow statistics for the flow. By default, for traditional full-flow netflow statistics, the full-flow mask is used. With UBRL, however, the masks can differ. If UBRL is configured on a given interface, the statistics are collected based on the mask configured for UBRL. Consequently, the system will not collect full-flow statistics for traffic transiting an interface configured with UBRL. For more details, refer to the "Configuring User Based Rate Limiting" section on page 29-35.
VLAN Statistics
With NetFlow support, you can report Layer 2 output VLAN statistics, as well as VLAN statistics for routed traffic in and out of a VLAN.
The following example shows the CLI output for a specific VLAN:
cat4k-sup4-2# sh vlan counters or show vlan id 22 count
* Multicast counters include broadcast packets
Vlan Id :22
L2 Unicast Packets :38
L2 Unicast Octets :2432
L3 Input Unicast Packets :14344621
L3 Input Unicast Octets :659852566
L3 Output Unicast Packets :8983050
L3 Output Unicast Octets :413220300
L3 Output Multicast Packets :0
L3 Output Multicast Octets :0
L3 Input Multicast Packets :0
L3 Input Multicast Octets :0
L2 Multicast Packets :340
L2 Multicast Octets :21760
Note NetFlow support has hardware limitations that restrict the platform support to a subset of all NetFlow fields. Specifically, TCP Flags and the ToS byte (DSCP) are not supported.
Configuring NetFlow Statistics Collection
To configure NetFlow switching, complete the tasks in these sections:
•Checking for Required Hardware
•Enabling NetFlow Statistics Collection
•Managing NetFlow Statistics Collection
•Configuring an Aggregation Cache
•Configuring a NetFlow Minimum Prefix Mask for Router-Based Aggregation
•Configuring NetFlow Aging Parameters
Checking for Required Hardware
Note When the switch has redundant supervisor engines, both supervisor modules should have the
Netflow Services Card sub-module.
To ensure that the necessary hardware is enabled, enter the show module command, as follows:
Switch# show module all
Chassis Type : WS-C4507R
Power consumed by backplane : 40 Watts
Mod Ports Card Type Model
Serial No.
---+-----+--------------------------------------+------------------+-----------
1 2 1000BaseX (GBIC) Supervisor(active) WS-X4515
JAB062604KB
2 2 1000BaseX (GBIC) Supervisor(standby) WS-X4515
JAB062408CB
6 48 10/100BaseTX (RJ45) WS-X4148
JAB032305UH
M MAC addresses Hw Fw Sw Status
--+--------------------------------+---+------------+----------------+---------
1 0001.6442.2c00 to 0001.6442.2c01 0.4 12.1(14r)EW( 12.1(20030513:00 Ok
2 0001.6442.2c02 to 0001.6442.2c03 0.4 12.1(14r)EW( 12.1(20030513:00 Ok
6 0050.3ed8.6780 to 0050.3ed8.67af 1.6 12.1(14r)EW( 12.1(20030513:00 Ok
Mod Submodule Model Serial No. Hw Status
----+-----------------------+-----------------+------------+----+---------
1 Netflow Services Card WS-F4531 JAB062209CG 0.2 Ok
2 Netflow Services Card WS-F4531 JAB062209AG 0.2 Ok
Switch#
Note Enabling this feature does not impact the hardware-forwarding performance of the switch.
The effective size of the hardware flow "cache" table is 85,000 flows. (The hardware flow cache for the Supervisor Engine V-10GE is 100,000 flows.) If more than 100,000 flows are active simultaneously, statistics may be lost for some of the flows.
The effective size of the software flow table is 256, 000 flows. The NetFlow software manages the consistency between the hardware and software tables, keeping the hardware table open by purging inactive hardware flows to the software table.
User-configured timeout settings dictate when the flows are purged and exported through NDE from the software cache. Hardware flow management ensures consistency between hardware flow purging and the user-configured timeout settings.
Software-forwarded flows are also monitored. Moreover, statistics will overflow if any flow receives traffic at a sustained rate exceeding 2 gigabits per second. Generally, this situation should not occur because a port cannot transmit at a rate higher than 1 gigabit per second.
Note By design, even if the timeout settings are high, flows will automatically "age out" as they approach their statistics limit.
Enabling NetFlow Statistics Collection
Note NetFlow Flow Statistics are disabled by default.
To enable NetFlow switching, first configure the switch for IP routing as described in the IP configuration chapters in the Cisco IOS IP and IP Routing Configuration Guide. After you configure IP routing, perform one of these tasks:
Exporting NetFlow Statistics
To configure the switch to export NetFlow Statistics to a workstation when a flow expires, perform one of these tasks:
Managing NetFlow Statistics Collection
You can display and clear NetFlow Statistics, including IP flow switching cache information and flow information, such as the protocol, total flow, flows per second, and so forth. You can also use the resulting information to obtain information about your switch traffic.
To manage NetFlow switching statistics, perform one or both of following tasks:
|
|
|
|---|---|
Switch# show ip cache flow |
Displays the NetFlow switching statistics. |
Switch# clear ip flow stats |
Clears the NetFlow switching statistics. |
Configuring an Aggregation Cache
Aggregation of NetFlow Statistics is typically performed by NetFlow collection tools on management workstations. By extending this support to the Catalyst 4500 series switch, you can do the following:
•Reduce the required bandwidth between the switch and workstations, because fewer NDE packets are exported.
•Reduce the number of collection workstations required.
•Provide visibility to aggregated flow statistics at the CLI.
To configure an aggregation cache, you must enter the aggregation cache configuration mode, and you must decide which type of aggregation scheme you would like to configure: autonomous system, destination prefix, protocol prefix, or source prefix aggregation cache. Once you define the aggregation scheme, define the operational parameters for that scheme. More than one aggregation cache can be configured concurrently.
To configure an aggregation cache, perform this task:
Verifying Aggregation Cache Configuration and Data Export
To verify the aggregation cache information, perform this task:
|
|
|
|---|---|
Router# show ip cache flow aggregation destination-prefix |
Displays the specified aggregation cache information. |
To confirm data export, perform the following task:
|
|
|
|---|---|
Router# show ip flow export |
Displays the statistics for the data export including the main cache and all other enabled caches. |
Configuring a NetFlow Minimum Prefix Mask for Router-Based Aggregation
The minimum prefix mask specifies the shortest subnet mask that will be used for aggregating flows within one of the IP-address based aggregation caches (e.g. source-prefix, destination-prefix, prefix). In these caches, flows are aggregated based upon the IP address (source, destination, or both, respectively) and masked by the longer of the Minimum Prefix mask and the subnet mask of the route to the source/destination host of the flow (as found in the switch routing table).
Note The default value of the minimum mask is zero. The configurable range for the minimum mask is from 1 to 32. You should chose an appropriate value depending on the traffic. A higher value for the minimum mask will provide more detailed network addresses, but it may also result in increased number of flows in the aggregation cache.
To configure a minimum prefix mask for the Router-Based Aggregation feature, perform the tasks described in the following sections. Each task is optional.
•Configuring the Minimum Mask of a Prefix Aggregation Scheme
•Configuring the Minimum Mask of a Destination-Prefix Aggregation Scheme
•Configuring the Minimum Mask of a Source-Prefix Aggregation Scheme
•Monitoring and Maintaining Minimum Masks for Aggregation Schemes
Configuring the Minimum Mask of a Prefix Aggregation Scheme
To configure the minimum mask of a prefix aggregation scheme, perform this task:
Configuring the Minimum Mask of a Destination-Prefix Aggregation Scheme
To configure the minimum mask of a destination-prefix aggregation scheme, perform this task:
Configuring the Minimum Mask of a Source-Prefix Aggregation Scheme
To configure the minimum mask of a source-prefix aggregation scheme, perform this task:
Monitoring and Maintaining Minimum Masks for Aggregation Schemes
To view the configured value of the minimum mask, use the following commands for each aggregation scheme, as needed:
Configuring NetFlow Aging Parameters
You can control when flows are purged from the software flow cache (and, if configured, reported through NDE) with the configuration aging parameters, Active and Inactive, of the ip flow-cache timeout command.
Active Aging specifies the period of time in which a flow should be removed from the software flow cache after the flow is created. Generally, this parameter is used to periodically notify external collection devices about active flows. This parameter operates independently of existing traffic on the flow. Active timeout settings tend to be on the order of minutes (default is 30min).
Inactive Aging specifies how long after the last packet is seen a flow is removed. The Inactive parameter clears the flow cache of "stale" flows thereby preventing new flows from starving (due to lack of resources). Inactive timeout settings tend to be on the order of seconds (default is 15sec).
NetFlow Statistics Collection Configuration Example
The following example shows how to modify the configuration to enable NetFlow switching. It also shows how to export the flow statistics for further processing to UDP port 9991 on a workstation with the IP address of 40.0.0.2. In this example, existing NetFlow Statistics are cleared, thereby ensuring that the show ip cache flow command displays an accurate summary of the NetFlow switching statistics:
Switch# config t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# ip route-cache flow
Switch(config)# ip flow-export destination 40.0.0.2 9991
Switch(config)# ip flow-export version 5
Switch(config)# end
Switch# show ip flow export
Flow export is enabled
Exporting flows to 40.0.0.2 (9991)
Exporting using source IP address 40.0.0.1
Version 5 flow records
2 flows exported in 1 udp datagrams
0 flows failed due to lack of export packet
0 export packets were sent up to process level
0 export packets were dropped due to no fib
0 export packets were dropped due to adjacency issues
0 export packets were dropped due to fragmentation failures
0 export packets were dropped due to encapsulation fixup failures
Switch#
Switch# show ip cache flow
IP Flow Switching Cache, 17826816 bytes
69 active, 262075 inactive, 15087 added
4293455 ager polls, 0 flow alloc failures
Active flows timeout in 30 minutes
Inactive flows timeout in 15 seconds
IP Sub Flow Cache, 1081480 bytes
0 active, 65536 inactive, 0 added, 0 added to flow
0 alloc failures, 0 force free
1 chunk, 1 chunk added
last clearing of statistics never
Protocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)
-------- Flows /Sec /Flow /Pkt /Sec /Flow /Flow
TCP-Telnet 28 0.0 167 40 0.0 20.9 11.9
TCP-other 185 0.0 2 48 0.0 6.2 15.4
UDP-DNS 4 0.0 1 61 0.0 0.0 15.5
UDP-other 13466 0.0 3396586 46 91831.3 139.3 15.9
ICMP 97 0.0 2 95 0.0 2.3 15.4
IGMP 1 0.0 2 40 0.0 0.9 15.1
IP-other 1120 0.0 38890838 46 87453.0 1354.5 24.0
Total: 14901 0.0 5992629 46 179284.3 227.8 16.5
SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts
SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts
Gi6/2 30.20.1.18 Gi6/1 30.10.1.18 11 4001 4001 537K
Gi6/2 30.20.1.19 Gi6/1 30.10.1.19 11 4001 4001 537K
Gi6/2 30.20.1.16 Gi6/1 30.10.1.16 11 4001 4001 537K
Gi6/2 30.20.1.17 Gi6/1 30.10.1.17 11 4001 4001 537K
Gi6/2 30.20.1.20 Gi6/1 30.10.1.20 11 4001 4001 537K
Gi6/2 30.20.1.10 Gi6/1 30.10.1.10 11 4001 4001 539K
Gi6/2 30.20.1.11 Gi6/1 30.10.1.11 11 4001 4001 539K
Gi6/2 30.20.1.14 Gi6/1 30.10.1.14 11 4001 4001 539K
Gi6/2 30.20.1.15 Gi6/1 30.10.1.15 11 4001 4001 539K
Gi6/2 30.20.1.12 Gi6/1 30.10.1.12 11 4001 4001 539K
Gi6/2 30.20.1.13 Gi6/1 30.10.1.13 11 4001 4001 539K
Gi5/48 171.69.23.149 Local 172.20.64.200 06 8214 0017 759
Gi6/1 30.10.1.12 Gi6/2 30.20.1.12 11 4001 4001 539K
Gi6/1 30.10.1.13 Gi6/2 30.20.1.13 11 4001 4001 539K
Gi6/1 30.10.1.14 Gi6/2 30.20.1.14 11 4001 4001 539K
Gi6/1 30.10.1.15 Gi6/2 30.20.1.15 11 4001 4001 539K
Gi6/1 30.10.1.10 Gi6/2 30.20.1.10 11 4001 4001 539K
Gi6/1 30.10.1.11 Gi6/2 30.20.1.11 11 4001 4001 539K
Gi6/1 30.10.1.20 Gi6/2 30.20.1.20 11 4001 4001 537K
Gi6/1 30.10.1.16 Gi6/2 30.20.1.16 11 4001 4001 537K
Gi6/1 30.10.1.17 Gi6/2 30.20.1.17 11 4001 4001 537K
Gi6/1 30.10.1.18 Gi6/2 30.20.1.18 11 4001 4001 537K
Gi6/1 30.10.1.19 Gi6/2 30.20.1.19 11 4001 4001 537K
Switch#
NetFlow Configuration Examples
This section provides the following basic configuration examples:
•Sample NetFlow Enabling Schemes
•Sample NetFlow Aggregation Configurations
•Sample NetFlow Minimum Prefix Mask Router-Based Aggregation Schemes
Sample NetFlow Enabling Schemes
Note Enabling NetFlow on a per interface basis is not supported on a Catalyst 4500 switch.
This example shows how to enable NetFlow globally:
Switch# configure terminal
Switch(config)# ip flow ingress
This example shows how to enable NetFlow with support for inferred fields:
Switch# configure terminal
Switch(config)# ip flow ingress infer-fields
Sample NetFlow Aggregation Configurations
This section provides the following aggregation cache configuration examples:
•Autonomous System Configuration
•Destination Prefix Configuration
Autonomous System Configuration
This example shows how to configure an autonomous system aggregation cache with an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:
Switch(config)# ip flow-aggregation cache as
Switch(config-flow-cache)# cache timeout inactive 200
Switch(config-flow-cache)# cache timeout active 45
Switch(config-flow-cache)# export destination 10.42.42.1 9992
Switch(config-flow-cache)# enabled
Destination Prefix Configuration
This example shows how to configure a destination prefix aggregation cache with an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:
Switch(config)# ip flow-aggregation cache destination-prefix
Switch(config-flow-cache)# cache timeout inactive 200
Switch(config-flow-cache)# cache timeout active 45
Switch(config-flow-cache)# export destination 10.42.42.1 9992
Switch(config-flow-cache)# enabled
Prefix Configuration
This example shows how to configure a prefix aggregation cache with an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:
Switch(config)# ip flow-aggregation cache prefix
Switch(config-flow-cache)# cache timeout inactive 200
Switch(config-flow-cache)# cache timeout active 45
Switch(config-flow-cache)# export destination 10.42.42.1 9992
Switch(config-flow-cache)# enabled
Protocol Port Configuration
This example shows how to configure a protocol port aggregation cache with an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:
Switch(config)# ip flow-aggregation cache protocol-port
Switch(config-flow-cache)# cache timeout inactive 200
Switch(config-flow-cache)# cache timeout active 45
Switch(config-flow-cache)# export destination 10.42.42.1 9992
Switch(config-flow-cache)# enabled
Source Prefix Configuration
This example shows how to configure a source prefix aggregation cache with an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:
Switch(config)# ip flow-aggregation cache source-prefix
Switch(config-flow-cache)# cache timeout inactive 200
Switch(config-flow-cache)# cache timeout active 45
Switch(config-flow-cache)# export destination 10.42.42.1 9992
Switch(config-flow-cache)# enabled
Sample NetFlow Minimum Prefix Mask Router-Based Aggregation Schemes
This section provides examples for the NetFlow minimum prefix mask aggregation cache configuration:
•Destination-Prefix Aggregation Scheme
•Source-Prefix Aggregation Scheme
Prefix Aggregation Scheme
This is an example of a prefix aggregation cache configuration:
!
ip flow-aggregation cache prefix
mask source minimum 24
mask destination minimum 28
In this example, assume the following configuration:
ip route 118.42.20.160 255.255.255.224 110.42.13.2
ip route 122.16.93.160 255.255.255.224 111.22.21.2
Both routes have a 27-bit subnet mask in the routing table on the switch.
Flows travelling from the 118.42.20.160 subnet to the 122.16.93.160 subnet whose source IP addresses match with a mask of 27 bits and whose destination IP addresses match with a mask of 28 bits are aggregated together in the cache statistics.
Destination-Prefix Aggregation Scheme
This is an example of a destination-prefix aggregation cache configuration:
!
ip flow-aggregation cache destination-prefix
mask destination minimum 32
!
Source-Prefix Aggregation Scheme
This is an example of a source-prefix aggregation cache configuration:
ip flow-aggregation cache source-prefix
mask source minimum 30
Feedback