What is Qos

1
What is Qos?

• Jason Washburn
• Abe Eberhardstedtler
• Kevin Jenkins

2
What is Quality Of Service(Qos)?

• Qos is a way to allocate resources in switches
  and routers so data gets to its destination,
  quickly, consistently, and reliably.

1
3
Why Do We Need It?

• Applications are increasingly demanding
• 1. Higher bandwidth
• 2. Lower network delay

2
4
How Is Qos Accomplished?

• 1. By Over engineering
• 2. By using policy-Based network techniques.

3
5
Over Engineering

• 1. Simplest approach
• 2. Newer faster ASIC chips
• 3. Hardware prices continually dropping

4
6
Types Of Data Prioritization

• 1. Implicit
• 2. Explicit

5
7
Implicit Data Prioritization

• A router or switch automatically allocates
  service levels based on Administrator-specific
  criteria such as
• 1. Type of application
• 2. Protocol
• 3. Source address
• Every incoming packet is examined to see if it
  meets the specific criteria.

6
8
Explicit Data Prioritization

• Explicit Qos lets the user or application request
  a particular level of service switches and
  routers attempt to meet the request. IP
  precedence also called IP Type of Service(TOS),
  is likely to become the most widely used explicit
  Qos technique.

7
9
Why Implicit Qos Is Most Popular Technique

• 1. Doesnt require as much router processing.
• 2. Less management
• 3. Stops users from configuring applications to
  request highest level of service.

8
10
What Is A Queue?

• Queues are simply areas of memory within a router
  or switch that is setup to contain different
  priority packets.

9
11
Queuing

• Once data is prioritized using implicit or
  explicit techniques, queues and queuing
  algorithms are used to provide the appropriate or
  desired Qos.

10
12
What Is An Algorithm?

• A algorithm is a mathematical equation that
  determines the order in which packets stored in
  queues are transmitted.
• Basic queuing algorithms transmit from the same
  queue in a FIFO order.
• More sophisticated queuing attempt to be fairer.
  For example Ciscos weighted fair queuing(WFQ)
  differentiates between bandwidth hogging
  applications and distributes the available
  bandwidth equally.

11
13
Current queuing limitations

• Todays routers and switches have very small
  number of queues available for Qos services.
• If more queues were available Qos would make more
  of an impact on current bandwidth management.

12
14
Congestion Control And Avoidance

• Congestion control allows workstations to
  throttle their transmission rates and slow
  traffic if the network drops packets.
• Random early detection(RED) randomly drops
  packets as queues fill up, causing stations to
  decrease their transmission rates so queues wont
  overflow.
• Separately these two options arent worth much
  but when used together they are very powerful for
  Qos.

13
15
Traffic Shaping

• Traffic shaping refers to a variety of techniques
  for manipulating and modifying data to help
  ensure Qos, such as packet segmentation. Packet
  segmentation is one of the reasons that ATM
  networks provide such high Qos.

14
16
Traffic metering

• Traffic metering is another form of traffic
  shaping. It spaces out the trains prior to
  transmission by temporarily storing packets in
  buffers to make sure the network isnt over
  loaded.

15
17
Putting It All Together

• In the near future policy-based management
  systems will tie all Qos services together.
  Policy servers in conjunction with existing
  network monitoring and management software will
  monitor the network to determine optimum Qos
  setting and dynamically configure routers and
  switches.

16
18
In Conclusion

• It remains to be seen how easy to use and cost
  effective these Qos systems will be. Proper
  network design is still the most crucial step in
  determining the success of your network design.
  Qos is too costly and complex to implement
  everywhere, and even the best Qos cant over come
  poor network design.

17
19
The End
Created by We Bad Production Crew