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Cisco CCDE v3 Training

71:39:25 Hours
226 Lectures


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117:12:56 Hours
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96:02:27 Hours
242 Lectures


Integrated Services QoS - Hard QoS

Integrated Services QoS - Hard QoS is first QoS approach, but currently we are not using. At the end of this post, you will know what is Integrated QoS, what was the idea with it and why it is not used today.  

Quality of service (QoS) is the overall performance of a telephony or computer network, particularly the performance seen by the users of the network. Two QoS approaches have been defined by standard organizations. These are:
  • Intserv (Integrated Services) and
  • Diffserv (Differentiated Services).
Intserv QoS demands that every flow requests a bandwidth from the network and that the network would reserve the required bandwidth for the user during a conversation. Think of this as on-demand circuit switching, each flow of each user would be remembered by the network. This clearly would create a resource problem (CPU, memory , bandwidth) on the network, and thus it was never widely adopted.

Not only allocation bandwidth for each and every flow on each network device in the path, but also keep tracking these flows and tearing down when the flow is terminated is very resource intensive and people thought this will not be scalable and we haven't seen deployment for it.

Protocol for Integrated Services was RSVP - Resource Reservation Protocol. Although we don't see usage of RSVP for Integrated Services, it is used in MPLS , by allocation Label for the destinations.

Integrated Services is known as Hard QoS because flows are assigned bandwidth, with the SoftQoS or commonly known as Diffserv - Differentiated Quality of Service, flows are not assigned a bandwidth, instead we have application classes which gets bandwidth allocation. Thus, considered as much more scalable.

Diffserv doesn’t require reservation; instead flows are aggregated and placed into classes. Each and every node can be controlled by the network operator to treat differently for the aggregated flows. Diffserv is a more scalable approach compared to Intserv and today if you are using QoS, you are dealing with Diffserv - Differentiated Services QoS or another name, SoftQoS!
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Orhan Ergun

Orhan Ergun, CCIE/CCDE Trainer, Author of Many Networking Books, Network Design Advisor, and Cisco Champion 2019/2020/2021

He created OrhanErgun.Net 10 years ago and has been serving the IT industry with his renowned and awarded training.

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