The top agenda for a network admin managing WAN networks is to ensure delivery of business critical applications. Say, a business is planning to implement QoS to prioritize traffic to their application servers. The bandwidth to be allotted can be determined only after finding out the current usage by these applications specifically over the same WAN link and that in comparison with other applications over the same link.
To solve this, NetFlow Analyzer with its IP Group feature can help.
Scenario :
Application performance degrades for two reasons:
1. Improper bandwidth allocation or lack of bandwidth for application delivery
2. Insufficient hardware on the hosted server
We will be discussing the first point alone.
The scenario is a company with 2 different sites. Site A is where the users are and Site B is where the company’s application server’s run. Users at site A performs data entry to the central database which is running at site B. The users are experiencing slowness when trying to add or read data from the central database. The network admin is asked to solve the issue after finding that the application hosting servers are fine.
He has to find out how much of the bandwidth available on the WAN link is being used specifically by the Central Database and based on the results, implement QoS policing which will prioritize this application without seriously dropping other minor applications using the same WAN link.
IP Group and Network traffic visibility:
The admin had the router at Site A to export NetFlow packets to the NetFlow Analyzer installation used by his enterprise. An IP group is then created (from Admin – IP Groups) in NetFlow Analyzer associating the IP Address of the server running the central database and also associating the port and protocol used by the database application. The ports for the application is associated to make sure only this particular application traffic is captured by the IP Group. After a couple of days, he generates a traffic report for business hours on the IP Group and can see that very less bandwidth is being utilized by the central database compared to the overall interface utilization.
He then generates a Capacity Planning report for both the IP group and for the WAN interface. The top applications used over time can be seen in both reports with 1 minute granular traffic reports. The top application report showed that the normal web traffic was the top application and the Central DB was using much lesser bandwidth. The administrator then decides to implement QoS policies on WAN interface of Site A to prioritize the traffic heading towards his Central Database. He implements the QoS as follows :
Custom Application Mapping :-
Router(config)#ip nbar custom DB tcp 1433
Traffic Class Creation :-
Router(config)# class-map database
Router(config-cmap)# match protocol DB
Policy Creation :-
Router(config)# policy-map DBtraffic
Router(config-pmap)# class database
Router(config-pmap-c)# bandwidth percent 70
The above configuration allocates 70% of the bandwidth to the database application.
To know more on creating QoS for custom application, check the below link:
Post Implementation:-
The network administrator now runs the IP group report which covers a time period after the QoS implementation and he sees that traffic utilized by Central Database has higher QOS priority. He runs the report on the link and can see that the top application for the link is now the database application and not HTTP. Users also now have normal access to the Central Database.
It is always important to have an idea on the current traffic pattern and usage before any network changes. This is just one of the many ways in which NetFlow Analyzer can help. We will see more over the next few blogs.
Thanks and Regards
Praveen Kumar
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