Introduction to Scrutinizer
with Mike Patterson
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Activating NetFlow Globally on your Existing Routers and Switches

I have an Adtran NetVanta Router I have a Cisco ASA Firewall I have a Cisco Router (Cisco IOS) I have a 4000 series Catalyst running in Hybrid or Native Mode I have a non-4000 series Catalyst switch I have a Cisco 4605 series with a daughter card configured with VLANs I have a Cisco Catalyst 4500 Series Switch I have a Cisco Catalyst 6500/6000 Series Switch I have a Cisco 7600 router I have a Cisco Nexus Series 7000 NX-OS I have an Enterasys Router I have an ESX Server running VMware I have an Extreme Networks Router I have a Juniper Router I have a Mikrotik Router I have a Riverbed Steelhead Appliance I have Vyatta Core 6 software

Activating sFlow Globally on your Existing Switches

I have an Alcatel Switch I have a D-Link DGS-3627 or DGS-3650 switch I have an Enterasys B3/C3/G3 series switch I have an ExtremeXOS Switch I have a Force10 Switch or Router I have a Foundry Switch I have an H3C MSR Series Router I have an H3C S5500-E1 or S7500-E Series Switch I have an HP Procurve Switch 2800 or 5300 series I have an HP Procurve Switch 5400, 3500, 2600 or 8200 series - running K code I have an HP Procurve Switch 5400zl, 3500yl and 6200yl I have a Juniper Switch or Router I have a Juniper EX3200 switch

Activating NetStream Globally on your Existing Routers and Switches

I have a 3com Router or Switch

Activating IPFIX Globally on your Existing Routers and Switches

I have a Nortel ERS 5500 & 8600 series router

Click here to learn how to verify that NetFlow is coming into Scrutinizer!

Below is a more in depth overview on some of the commands that can be involved.

Set this <interface number> value for example to: FastEthernet0/0. This specifies the interface that the NetFlow is going to be sent from. This is recommended because if the router is restarted and the interface number changes or if a backup connection goes active, the interface the flow is coming from will appear to not have changed. This is important as we don’t want to lose historical data.

Also, using a loopback address allows for real interfaces to go down and if there is still a route back to Scrutinizer the NetFlow packets will make it. If you don’t use this command, the following example could occur: if you have configured the source as wan interface 1 and it goes down but, there is a route back via wan interface 2 then the NetFlow may not get sent to Scrutinizer even though the network connection is active and traffic is being passed.

    Command to type: ip flow-export source <interface number>

The command below breaks up long-lived flows into 1-minute segments. You can choose any number of minutes between 1 and 60; if you leave the default of 30 minutes you will get spikes in your utilization reports.

    Command to type: ip flow-cache timeout active 1
Use the command below to specify the IP ADDRESS (e.g. 10.1.1.5) of your Scrutinizer Host and the "Listener Port" specified in the Configuration under the Settings tab. Port 2055 is monitored by default.

    Command to type: ip flow-export destination <IP ADDRESS> 2055
The source interface is used to set the source IP address of the NetFlow exports sent by the  router. Scrutinizer may send SNMP requests to the router using this address. Use the  command below if you experience problems. You can set the source interface to an Ethernet or  WAN interface instead of the loopback.

    Command to type: ip flow-export source loopback 0
Use the command below to set the export version. Version 5 is the most recent full export  version supported by routers.

    Command to type: ip flow-export version 5
The command below ensures that flows that have finished are exported in a timely manner. The  default is 15 seconds; you can choose any value between 10 and 600. Note however that if you  choose a value that is longer than 250 seconds Scrutinizer may report traffic levels  that appear low.

    Command to type: ip flow-cache timeout inactive 15
Use the command below to display the current NetFlow configuration. Issue this in normal (not  configuration) mode!

    Command to type: show ip flow export
Issue these commands in normal mode to summarise the active flows and to give an indication of  how much NetFlow data is being transmitted by the router.

    Command to type: show ip cache flow
    Command to type: show ip cache verbose flow
This enables Cisco Express Forwarding, which is required for NetFlow in most recent IOS  releases.

    Command to type: ip cef

MIB Links
Download the CISCO-NETFLOW-MIB Version 2
Download the CISCO-NETFLOW-MIB Version 1

For more information and a list of dependencies for the CISCO-NETFLOW-MIB, use the Cisco SNMP Object Navigator.

Learn more about configuring NetFlow on your router or switch at the Cisco website.

 


cliff m
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"The beauty of NetFlow is, because it is a standard, you can look at data from different vendors and still apply the correct level of forensics or traffic analysis to it."
Cliff Meltzer, Cisco Systems, Inc.
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