Overview

Bandwidth  management, in general, is a simple concept. The idea is to be able to differentiate  or classify user traffic  according to a wide array  of criteria and then assign various priorites to each  classified packet or session. For example, bandwidth  management allows an administrator  to give HTTP traffic a  higher priority over SMTP traffic, which in turn may have a higher priority over FTP traffic. At the same time, a bandwidth management solution can  track the actual bandwidth  used by each application  and set limits as to how  much each classified traffic  pattern can utlise.

There  are a variety of methods  used in order to enforce  the bandwidth management  policies configured by  an administrator. The simplest  method would be to discard  packets when certain thresholds are reached or when certain  pre-allocated session buffers  are overflowing. More complex mechanisms include TCP rate shaping and priority  based queuing.

TCP  rate shaping uses the inherent  flow control mechanisms of the TCP protocol. By  adjusting parameters in the packets` TCP headers,  a bandwidth management  solution can signal the end nodes to throttle the  rate at which to transmit packets. Needless to say,  the mechanism only works  with TCP sessions. TCP  rate shaping also has some  uncertainties assaociated  with it, as the amount  of bandwidth associated with sessions can rarely be exactly enforced. Rate shaping also does not work well with protocols that use short lived sessions (such as HTTP), since such sessions usually end before  the bendwidth manager has decided how to shape the rate of the session.

Priority besed queuing is a means by which all classified  packets are placed in packet  queues, each with its own preset priority. A number  of queues are available and when it comes to traffic forwarding, packets are  forwarded from the higher priority queues first. This is an oversimplified  version of what really  happens, but it presents  the general concept. Various algorithms and saftety measures should be deployed  to ensure methodical packet forwarding as well as protection  against "starvation", where lower priority packets wait in queues for intolerably long amounts of time.

This type of solution can be  useful when trying to managed and monitor traffic across internal or external WAN links. It can also be usefull  when trying to priorties  ERP Traffic over email  traffic. E.g SAP ERP packets  over Lotus Notes email  traffic. These types of  product can also be useful  if you want to know what  your utilisation is on  certain WAN links, i.e  they will show you when  your links are under heavy  load and by what type of  traffic in detailed reports.  This type of information  can be useful for planning  the amount of bandwidth you will need in the future  in relation to how many users that you have. There are many instances where bandwidth management products  can be implemented.

Please call 0870 421 4023 to find out how your company  can benefit from developing a bandwidth management solution, or e-mail bandman.team@Whitehelm.com requesting more information.