enhanced general switch management protocol

Salim Hariri HPDC Laboratory http://www.ece.arizona.edu/~hpdc

Enhanced General Switch Management Enhanced General Switch Management ProtocolProtocol

Salim HaririDepartment of Electrical and Computer Engineering

HPDC Laboratory

The University of Arizona

ECE Building, Room 421Tucson, Arizona, AZ 85750

Tel: (520) 621-4378, Fax: (520) 621-8076

[email protected], www.ece.arizona.edu/~hpdc


Why Programmable Networks?

Rapid creation, deployment and management of new services in response to user demands.

Change in the nature of traffic due to the wide variety of applications and services.

Application specific demands for resources. Need for the separation of communication hardware

from control software. Better control over the network resources for its

effective use.


Classification of Programmable Networks

Programmable Networks

IPATM

Active Networks(Dynamic Approach)

q-GSMPGSMP e-GSMPP 1520 Model

Discrete Approach

(Out of Band)

Integrated Approach(In band)

Open Interface Networks(Static Approach)


Provides abstractions in the layers of a node to define programmable interfaces.

Allows applications and middle-ware to manipulate low-level network resources.

Uses APIs to control the various layers.

Open Interface Networks


Open Interface Networks (Contd.)

Advantages:– Separation of service business.– Separation of vendor business.– Faster standardization.– Extensibility– Richer Semantics


Quality of Service (QoS) refers to the capability of the network to provide better service to selected network traffic irrespective of the underlying technologies.

The goal of QoS is to provide priority including dedicated bandwidth, controlled jitter and latency and improved loss characteristics.

Meaning of QoS


QoS in OSI Model


Providing QoS over ATM is easier– Fixed length of cells– Well defined types of services.

Techniques for providing QoS in ATM– General Switch Management Protocol (GSMP)– q-GSMP

QoS over ATM


General Switch Management Protocol(RFC 1987)

Open Interface, switch control protocol. Connection oriented network technologies. Point-point and Multi-point connections. Adjacency protocol -synchronize state across link. Master-Slave relationship between controller and the

switches


GSMPClassifier Regulator SchedulerVPC/VCCs

Policer

Output Port

Confirming

Confirming

Excess

Excess

QoS Class

QoS Class


GSMP Message Sequence

Switch controller Network

Switch Mapping

Connection Management

Port ManagementConfiguration Information

StatisticsEvents

qGSMP ATM Switch


q-GSMP

Provides QoS extensions to the GSMP. Supports new messages enabling selection of:

– QoS constraints– Buffer management – Scheduling algorithms– Memory allocation schemes.

Specific to ATM switches.


q-GSMP

Switch Controller

SchedulerScheduler

Network

Switch Mapping

Buffer Manager

SR Estimator

qGSMP ATM Switch

Connection Management

Port Management

Configuration Information

StatisticsEvents

QoS Management

QoS Configuration Management

QoS Statistics

QoS Events


QoS over IP

Issues: IP was not meant to provide better than the best effort

QoS. Complex scheduling and buffer management due to

variable length packets. Changes in the traffic pattern at the output of a router

due to traffic aggregation.


Traditional IP networks support only best effort delivery.

Convergence of voice and data requires IP network to provide deterministic guarantees for real time traffic.

Multimedia traffic require both bandwidth and delay guarantees.

Need for IP QoS


P-1520 Model

Defines a set of Programmable interfaces for the development of the protocol and management of the infrastructure.

Defines four interfaces: – Value Added Service Level– Network Generic Services Level– Virtual Network Device Level– Physical Elements Level


P-1520 Model

Algorithms for value added communications

Algorithms for routing and connection management

Virtual Network Device

Physical Elements (Hardware)

V Interface

U Interface

L Interface

CCM Interface

Value Added Services Level

Network Generic Services Level

Virtual Network Devices Level

PE Level


IP reference Model


Features of our IP Model

Extension of Integrated Services Model of Clark,Shenker and Zhang[ ].

Conforms to P1520 model[ ] of programmability.

Complies with ForCES architecture[ ] of network entity.

Incorporates ETRI’s Router Architecture.


ETRI’s Router Architecture


Scheduler and Queues

Outbound Packets

Scheduler

Packets inVarious Queues


Algorithm for Schedulability

We consider the Diffserv QoS, classes of service.

Let us assume that DS(i) = ith class of service.

Vector Q(i) = [ q1(i) q2(i),…….qm(I)] be the QoS Parameters for the ith class.

We define a matrix Qm consisting of all the QoS classes and their respective parameters.

Q(1) q1(1) q2(1) ………qm(1)

Qm = Q(2) = q1(2) q2(2) ………qm(2)

Q(n) q1(n) q2(n) ………qm(n)


Packet

Classification

Switch/Backplane

Media

I/F

01

02

n-1

n

Input of a Router

Bandwidth/Delay Shaped Queues

Per-destQueues

Scheduler

InboundPackets


A table K is maintained by the router to indicate the number of packets in each QoS class.

K = [k1,k2…………kn]

Bo = port bandwidth

B = total bandwidth.

Bo = Σ ki * q1(i)

if (q1(i) <= (B-Bo)) then

BandSchedulable =TRUE;

else

BandSchedulable = FALSE;


Packet

Processor

Switch/Backplane

Output from a Router

Bandwidth/DelayShaped Queues

Scheduler

Media

I/F

OutboundPackets


Admission Control Algorithm

The Admission control is made at the line cards.

Token Bucket algorithm is used to characterize the flows.

A new flow is admitted if the following condition is satisfied

PBRnew + NΣ i=1 PBRi <= ρC

where

PBR = peak bit rate

ρ = admissible load of capacity

C = total capacity


e-GSMP

Envisages to provide QoS services over a primarily IP network.

Is an Open Interface approach. Defines a Master-Slave relationship between the

Controller and the IP Routers. Allows an interactive approach to provide

programmability.


e-GSMP

Switch FabricInput Ports Output Ports

Multiplexer

Multiplexer

Multiplexer

1

m

Switch Mapping Schedulable Region Estimators


To support the Intserv and Diffserv frameworks. To define schedulable regions to implement

admission control. To allow for different scheduling and buffer

management techniques.

e-GSMP


Concluding Remarks

enhanced general switch management protocol

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