This blog may need prior reading of my first blog about Flexible NetFlow. We have already discussed about the advantages of Flexible NetFlow and migration from traditional NetFlow versions to FNF. To make this transition smooth Cisco provides the option of pre-defined flow records which can be used to configure Flexible NetFlow without investing a lot of time. And as I mentioned earlier it also helps your existing NetFlow V9 collector to parse exported data. However to use Flexible NetFlow to its fullest potential or to monitor a specific network behavior, you should create your own customized records.
Let’s see how to configure Flexible NetFlow to export flow statistics. Flexible NetFlow export can be configured in three easy steps.
1. Configure the exporter
2. Configure the Flow Monitor with the pre-defined Flow Record and Flow Exporter attached to the monitor.
3. Add the Flow Monitor to the interface to monitor either ingress (input) or egress (output traffic).
1. Configuring Exporter
Flow exporter can be configured with a unique name. Multiple Flow exporter profiles can be configured. Below is the configuration to configure Flow Exporter.
flow exporter <exporter name>
destination <ip address of ME NFA>
transport udp <port number>
Example configuration:
flow exporter me_nfa_analyzer
destination 192.168.1.1
transport udp 9996
2. Flow Monitor and Flow record configuration
Flow record configuration defines the fields exported via NetFlow protocol. Flexible pre-defined flow records are based on the original NetFlow ingress or egress caches. Cisco provides a unique keyword to identify the pre-defined records and these records can associated with a Flexible NetFlow Flow record configuration. The Flexible NetFlow "netflow-original" and netflow ipv4 original-input are predefined records and these two records can be used interchangeably to export the basic key fields and time stamp fields. Flow monitors can also include packet sampling information if sampling is required.
flow monitor <monitor name>
record netflow-original
exporter <exporter name>
cache timeout active <seconds>
cache timeout inactive <seconds>
Example Configuration:
flow monitor me_nfa_monitor
record netflow-original
exporter me_nfa_analyzer
cache timeout active 60
3. Adding Flow Monitor to the interface
Flow Monitor has to be attached to a specific physical or logical interface to export flow statistics for that particular interface. Below is the configuration to attach flow monitor to a specific interface.
interface <interface name>
ip flow monitor <monitor_name> input
Example Configuration:
interface serial0/0
ip flow monitor me_nfa_monitor input
And the above configuration can be verified by "show flow monitor" command. As I mentioned earlier Flexible NetFlow has numerous advantages and has the power of supporting new performance monitoring statistics as soon as they are available. Flexible NetFlow is an evolving technology available in Cisco devices to help with visibility into how network assets are being used and the network behavior.
Please find more information on FNF here.
ManageEngine constantly studies the market and user demands to support new technologies. In fact ManageEngine NetFlow Analyzer is the first tool to support multiple bandwidth and performance monitoring technologies like NetFlow, NBAR and CBQoS in the market. And currently ManageEngine NetFlow Analyzer supports Flexible NetFlow without any issues. Please write your questions to netflowanalyzer-support@manageengine.com. We are happy to assist you at any moment.
Thanks
Raj
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Hello,
Some of our community folks using ME NetFlow Analyzer to monitor their Juniper firewalls SSG 500 series. It supports policy based netflow/JFlow export.
Can you share us the netflow/JFlow configuration to enable NetFlow/JFlow on these firewalls?
Thanks
Raj
Flexible NetFlow is the next generation flow export technique promoted by Cisco Systems. As the word depicts it is highly flexible based on user requirements and to monitor specific network behaviour. Traditional NetFlow used a fixed seven tupple of IP information to identify a flow most of the time. Advantages of Flexible NetFlow
1. Flexibility to choose the desired export fields.
2. Reduce the number of flows and allows CPU to perform efficient routing and switching
3. Convergence of multiple accounting technologies into one accounting mechanism
Flexible NetFlow and NetFlow V9
The export protocol of choice for Flexible NetFlow is the NetFlow Version 9 export protocol, but unfortunately and to date, NetFlow Version 5 has been a much more widely used protocol because of the legacy Cisco IOS® Software images that are still around that supported the NetFlow v5 export protocol only and worked very well. However Cisco claims the future is going to be Flexible NetFlow. And believe it this migration is going to very smooth since Flexible NetFlow can also be configured to export some predefined flow records using the NetFlow Version 5 protocol format for backward compatibility. This helps your existing collectors can work with Flexible NetFlow until you find a real requirement to use additional fields offered by Flexible NetFlow.
Flexible NetFlow Configuration
Traditional NetFlow configuration is pretty much straight forward. Flexible NetFlow consists of components that can be used together in several variations to perform traffic analysis and data export, and the new command-line interface (CLI) configuration follows the same traditional logic.In this user-defined flow records and the component structure of Flexible NetFlow make it easy to create various configurations for traffic analysis and data export on a networking device with a minimum number of configuration commands.
Flexible NetFlow consists of components that can be used together in several variations to perform traffic analysis and data export, and the new command-line interface configuration follows the same traditional logic.
Let's see this components in detail
Flow Monitor:
A Flexible NetFlow Flow Monitor describes the NetFlow cache or information stored in the cache. The Flow Monitor contains the Flow Records or key and non-key fields within the cache. Also, part of the Flow Monitor is the Flow Exporter which contains information about the export of NetFlow information including the destination address of the NetFlow collector. The Flow Monitor includes various cache characteristics including the timers for exporting, the size of the cache and if required, the packet sampling rate.
Flow Record:
A Flow Record is a set of key and non-key NetFlow field values used to characterize flows in the NetFlow cache. Flow Records may be pre-defined for ease of use or customized and user defined. A typical pre-defined record will aggregate flow data and allow users to target common applications for NetFlow. User defined records will allow selection of specific key or non-key fields in the Flow Record. The user defined field is the key to Flexible NetFlow allowing a wide range of information to be characterized and exported by NetFlow. It is expected that different network management applications will support specific user defined and pre-defined Flow Records based on what they are monitoring (ie: security detection, traffic analysis, capacity planning).
Flow Exporter:
The Flexible NetFlow Exporter allows the user to define where the export can be sent, the type of transport for the export and properties for the export. Multiple exporters can be configured per Flow Monitor or the same exporter can be used by multiple monitors.
The following figure shows the flow monitor and it components.
In our next blog we are going to use a pre-defined (defined in IOS itself) flow record to export netflow records using Flexible Netflow. In the meanwhile if you have any queries. please write to netflowanalyzer-eesupport@manageengine.com
Thanks
Raj
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We have posted a number of blogs to share information on how to use
NetFlow technology and NetFlow Analyzer to manage your network better.
Those blogs will definitely continue to give you more ideas to put the
product to better usage but we will also discuss about some of the
common issues that you may have come across in the product and how they
can be resolved.
NetFlow Analyzer
generates traffic reports based on the NetFlow packets exported from
the router. Based on the information in the NetFlow packets, the
product displays the traffic passing through the interfaces of the
exporting device.
One issue that is frequently reported is that the traffic utilization shown in NetFlow Analyzer is more than the actual traffic on the interface. Reports
showing more than actual utilization or more than 100 % utilization can
be resolved quickly by checking a few points on the exporting device
and the product.
Incorrect active timeout:
The
traffic reports in NetFlow Analyzer is shown with a 1 minute
granularity, ie. NetFlow Analyzer shows details of the traffic for each
minute. By default, the active timeout on the NetFlow exporting devices
is 30 minutes, which means that the information about the traffic that
passed through the interface in the previous 30 minutes is exported at
the 30th minute.
Since NetFlow Analyzer reports traffic
every minute, the export of 30 minutes information all at once leads to
the product's reports showing a spike every 30 minutes. The incorrect
traffic details for that minute leads to showing incorrect speed which
thus leads to worng utilization calculation. To avoid this, simply
check if the active timeout on the router is set to 1 minute using the
command "ip flow-cache timeout active 1""
Multiple NetFlow commands:
NetFlow can be enabled on the router using any one of the three commands:
ip
route-cache flow : - This command can be applied on all main
interfaces and will automatically enable NetFlow on the sub interfaces
too. This command accounts for the IN traffic across an interface.
ip
flow ingress :- Some of the newer IOS supports this command
which also accounts for the IN traffic across an interface. The
difference is that this command needs to be applied on a sub-interface
level
ip flow egress :- The same as 'ip flow ingress' but this command accounts for the OUT traffic across an interface.
NetFlow
can be enabled on the interfaces of the router by applying any one of
the above mentioned command, but most of the netwrok admin enable
either "ip flow ingress" or "ip route-cache flow" on the interfaces for
traffic accounting. When all these commands are applied on the
interfaces, it causes the same traffic to be counted multiple times
again causing the product to show incorrect traffic stats and thus
incorrect utilization reports.
Incorrect link speed in NetFlow Analyzer:
NetFlow Analyzer calculates the utilization based on the link speed. For
example, if the link has capability to handle 1 Mbps and the actual
traffic passing through an interface is about 512 Kbps, the utilization graph in NetFlow Analyzer displays the traffic percentage as 50 %. Here
is the formula which explains the utilization calculation on NetFlow
Analyzer.
Utilization = Actual Speed/Link Speed * 100
So,
if the link speed is not updated properly in NetFlow Analyzer, the
utilization shown in NetFlow Analyzer will be different than the
actual. NetFlow Analyzer can determine the interface speed if you set
the appropriate SNMP Port and Community for the router on NetFlow Analyzer. This can be done from the 'Set SNMP Parameters' icon on the
'Interface View' right next to the router name or you can set the
interface speed manually for each interface on NetFlow Analyzer (from
the Edit Settings icon on the 'Interface View' next to the interface
name). You can refer to this blog for more details.
Non dedicated burstable bandwidth:
Certain ISPs allows
you to use over the allocated bandwidth depending on the other
customers sharing that link. So, even though the max bandwidth is
2Mbps, the ISP may allow you to use even more based on availability.
This also affects the accurate reporting on NetFlow Analyzer causing
incorrect bandwidth utilization values and even more than 100%.
ESP and GRE traffic:
This is another reason for traffic
to get double counted in NetFlow Analyzer. With NetFlow data, the
tunnel traffic will be accounted as the normal traffic before
encryption and again as the encrypted traffic. NetFlow Analyzer have an
option to filter this kind of encrypted tunnel traffic from the
reports. This option is availble under Product Settings - Advance
Settings - ESP or GRE Filter.
To know more about the about ESP and GRE traffic double count, check this link.
If none of the above resolves the issue, please find the technical explanation on what could still be causing this:
Any
analyzer tools calculates the OUT traffic of an interface based on the
IN traffic of the interface that sends traffic to it. When traffic is
passing from higher speed interface to lower speed interface, the
calculation of OUT traffic from a higher speed IN traffic causes
incorrect traffic utilization to be shown on the OUT traffic.
The
above reason for more than 100 % utilization on OUT traffic can be
resolved by enabling only "ip flow egress" on all the interfaces.
If you have any further queries on this, kindly send us a email at netflowanalyzer-support@manageengine.com.
Thanks
Praveen
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Being a niche player in the SAAS market, Zoho brings an amazing level of engineering expertise to ManageEngine in building highly secure and scalable distributed applications. And hopefully you know, Adventnet has recently changed its name to Zoho Corp and formed three divisions namely ManageEngine, Zoho, and WebNMS.
Growing network needs complicate the job of network administrators and bring in new challenges. Network Administrators need robust,cutting-edge network management tools to quickly troubleshoot network incidents and increase the network performance. However considering the economic situation, it is very important to choose the right application which can leverage on network performance management data from multiple technologies and of course at an affordable cost.
ManageEngine NetFlow Analyzer team constantly interacts with its customers, technology companies and VARS to prioritize the road map. Whenever a new technology is introduced in the product, all existing customers see an immediate value by means of simple free upgrade instead of paying a hefty price. Here the ROI includes cutting bandwidth upgrade costs due to increased visibility using ManageEngine NetFlow Analyzer, avoid unauthorized bandwidth usage and increase the efficiency of business critical applications with almost zero implementation cost.
Multiple technologies - Single Solution:
Cisco NetFlow:
Cisco's NetFlow technology exports flow records from any IOS capable routers and switches. The exported flow records contain information about protocols, ports, source, destination IP addresses and much more.
NetFlow Analyzer provides several instant reports to monitor bandwidth including top talkers, top protocols, top conversations, and more. Apart from these pre-defined bandwidth reports, NetFlow Analyzer also includes options to search for specific bandwidth usage details based on IP address, host name, protocol, and more.
Bandwidth Monitoring without Probes
NetFlow Analyzer does network bandwidth monitoring using NetFlow. NetFlow exports are collected, correlated, and analyzed to get granular details to monitor bandwidth usage across each WAN link. There is no need for hardware probes to monitor bandwidth usage. NetFlow Analyzer is an all software solution which is suitable for both Windows and Linux.
Real-time Bandwidth Monitoring
Bandwidth monitoring reports for each interface shows the current, average, and peak bandwidth usage patterns across each NetFlow-enabled interface. With these bandwidth usage statistics you can get instant visibility into how much bandwidth was used up by hosts, applications, and conversations across a specific interfaces.
Application-wise Bandwidth Distribution
To monitor bandwidth utilized by different applications, NetFlow Analyzer gives you instant visibility into which applications are using up maximum bandwidth. You can also drill down to see the top sources, destinations and conversations using the bandwidth. With such granular detail, network troubleshooting and problem resolution take far less time than with traditional tools.
Cisco NBAR:
Cisco NBAR (Network Based Application Recognition) engine runs on the IOS and does deep packet inspection to identify applications riding on regular ports. For example TCP 80 can be identified as kazza2, BitTorrent, Napster etc. The respective utilization, volume and speed can be polled through SNMP protocol over time.
NBAR reports are very useful to set the Quality of Service (CB-QoS) policies. NBAR and QoS policies can work together to prevent bandwidth stealing applications and increase the efficiency of business critical applications.
Cisco CB-QoS (Class Based - Quality of Service):
We have discussed a lot about deploying CB-QoS policies for improved network performance. You can find CB-QoS blog series in this link. Cisco CB-QoS is the simplest way to prioritize network traffic.
Having insights over pre and post policy metrics, network administrators can modify their CB-QoS policy configuration for improved performance and to avoid any impact to business critical applications due to misconfiguration.
This is why we call ManageEngine NetFlow Analyzer is a powerful traffic analysis and forensic solution for a network of any size. Try our 30 days all feature version and write your queries to netflowanalyzer-support@manageengine.com
Thanks
Raj
The drive for QoS has become very strong in recent years because of evolving needs for enterprises to carry different types of services including voice, video, streaming music, web pages and email on a single link. One of the most complex tasks of a network architect is to design a robust network and also ensure the quality of end to end applications delivered across branch locations and data centers.
Quality of Service refers to the ability to provide better treatment for some applications over other services in the network. The primary goal of implementing QoS in business critical networks includes priority routing for critical applications through dedicated bandwidth, controlling jitter and latency. Now a day’s most of the enterprises rely on the service provider network for their day to day branch office transactions.
Typically, networks operate on the basis of best-effort delivery, in which all traffic has an equal priority and an equal chance of being delivered. When congestion results, all traffic have an equal chance of being dropped. QoS selects network traffic, prioritizes it according to its relative importance and uses congestion avoidance to provide priority-indexed treatment. Configuring QoS can also limit the bandwidth used by non critical network traffic and so makes network performance more predictable and bandwidth utilization much more effective.
Configuring and validating quality of service involve four steps.
A. Application discovery and grouping
B. Implementing Quality of Service (QoS)
C. Verification of QoS treatment for interested traffic
D. Validating QoS configuration for application performance
This blog focuses on application discovery and grouping of similar type of applications.
Application discovery and grouping:
To apply QoS policies, it is very important to identify applications that are competing for bandwidth. NetFlow and NBAR is an excellent data source to identify most of the applications. NetFlow exports consist of port and protocol information which can be mapped to a well known application conversation. Cisco embeds NBAR (Network Based Application Recognition) engine that can identify traffic up to the application layer. It is extremely useful in identifying peer-to-peer applications.
ManageEngine NetFlow Analyzer is a unique blend of NetFlow and NBAR technologies. In addition to static NetFlow based port and protocol application detection, it also supports NBAR to identify most of the peer-to-peer applications.
Application identified through NetFlow data export
NetFlow port and protocol based application detection:
NetFlow Analyzer maintains the port and protocol mapping for more than 1500 applications for application classification. Additionally it is also possible to map new applications that are running on particular IP address/range or a range of ports. These applications can be grouped into single application. For example, the user can classify all the database applications like Oracle, MySql, MS-Sql in to one group called the database group.
Application distribution graph over time
NBAR (Network Based Application Recognition)
Intelligent application classification by examining the data payload helps ensure the network bandwidth is used efficiently by working with QoS feature. Unlike NetFlow, which relies on port & protocol for application categorization, NBAR approach is useful in dealing with malicious software using known ports to fake being “priority traffic”, as well as non-standard applications using non-determinant ports. The biggest advantage in using NetFlow Analyzer is that the user can enable NBAR on the fly from the web GUI for instant visibility and can it turn off at peak times to save CPU cycles for routing.NBAR is supported in most Cisco switches and routers and values are retrieved through SNMP. It is possible to identify applications like Kazaa, Edonkey and Skype, which use dynamic ports to transfer data. NBAR does deep packet inspection of traffic to identify these applications which normally cannot be identified with NetFlow and reports on the bandwidth they occupied.
Based on the results, we can group applications under various categories. The grouping can be done as delay sensitive applications like voice or real time video in one category, applications that use high bandwidth in another and those that are tolerant to packet loss or delay can be considered as another group. In the next blog, we will discuss about implementing QoS policies for these groups of applications based on their business criticality and priority.
Raj
ManageEngine NetFlow Analyzer
Corp