Zte ZXR10 5900 Product Description page 36

ZXR10 5900 5200 Product Description
 Queue Management and Scheduling
3.19.1.3 Service Model
One way to implement QoS is to allocate resource to each data flow based on the
requirements of the service level. This method of using "resource reservation" to allocate
the bandwidth will not be suitable for "Best-effort" applications. Since bandwidth is
limited, the designer of QoS introduces the concept of priority, which makes "Best-effort"
data flows can also be given certain level of guarantee. Therefore, IP QoS can be
classified into two fundamental models:
 Resource reservation-based: network resource is allocated and resource
management strategy is established based on QoS requirements of one certain
service. The IntServ (Integrated Services) proposed by IETF (Internet Engineering
Task Force) is based on this strategy. And RSVP protocol (Resource Reservation
Protocol) is the core of this model
Priority-based: edge network nodes to classify, shape and mark the service flows.

Core nodes allocate the resource based on resource management strategy, and
give priority to those services which has more demanding requirement in QoS.
DiffServ (Differentiated Services) proposed by IETF is based on this strategy.
These QoS methods can be applied to single data flow or aggregate flow. IP QoS can be
classified as follows based on different data flow applied to:
 Applied to single data flow: single data flow is a single, one-direction data flow
between two applications (sender and receiver). It can be categorized based on five
parameters of transmission protocol, source address, source port number, target
address and target port number.
Applied to aggregate flow: aggregate flow is comprised by two or more single data

flow, which have something in common in respects of one or more parameters, for
example marking, priority and/or some authentication parameters.
To settle the problem of QoS, IETF has proposed several service models and systems:
 Integrated service (IntServ) and Resource Reservation (RSVP): to put forward flow
specification (Flowspec) to the network in RSVP signaling, create and dismantle
service flow state on the transmission path. Host and network create and maintain
the service flow state information. Though RSVP is often applied in single data flow,
it also applied in resource reservation of aggregate flows.
Differentiated Services: in the differentiated services network, the border router

divides the user stream into different levels based on their stream profile and then
aggregates them into stream aggregate, and saves the aggregate information into
the DS code point domain of IP packet header, which is called DSCP (Differentiated
Services Code Point). The internal nodes provide scheduling and forwarding
services of different quality based on DSCP.
30 © 2010 ZTE Corporation. All rights reserved. ZTE Confidential Proprietary