document

QoS Routing

ISDLmhwon@isdl.snu.ac.kr

Quality of Service Routing Algorithms for Bandwidth-Delay Constrained

Applications

Yi Yang, Jogesh Muppala et al

Problem Classification Link-optimization routing Link-constrained routing Path-optimization routing Path-constrained routing

Link-* is concerned with bandwidth. Path-* is concerned with delay.

Previous Related Work Min-Hop WAPF( Widest Path Avaiable Path First ) SWP( Shortest Widest Path ) MIRA( Minumum Interference Routing Algorithm )

SWP & MIRA introduce the concept of ‘ingress-egress pair’ to the problem.

Attention to MIRA MIRA makes path selection similar to

the methods this paper suggests The concept of ‘Critical Link’ In routing requests it avoids critical

link for future request not to be rejected.

It does not guarantee the delay bound.

Define Problem

Server Based RoutingOr Source Routing

: Router

: Link ( with B and D )

Objective Maximize utilization of networks Maximize call blocking ratio Minimize the number of requests

rejected

requestsofnumbertotal

rejectedrequestsofnumberratioblockingcall

___

_____

DWC( Delay Weighted Capacity ) For some ingress-egress pair Prefer the powerful machine( link )

(B=5,D=3)

(5,2)

(5,2)

(5,2)

(5,3)

(5,4)

(5,2)

(5,2)

(5,3)

(5,1)

(5,1)

DWC( cont’d ) Is metric used to measure the potential of the network t

o process some future request

stst

i LPLPist

ist

st D

BDWC

This paper suggest the routing method that does not decrease DWC metric (much).

Critical Link In DWC link is sorted in order by link-

delay. The request is made up of delay-

requirement and bandwidth-requirement. The critical link is the bottleneck of the

path that limit its bandwidth.

Critical Link( cont’d )

The set of bottleneck link of In routing some request , do so that critical links are not used.

},......,,{ 21 stkstststst CCCC

istLP

Routing Algorithm MDWCRA ( Maximum Delay-Weighted

Capacity Routing Algorithm )

Objective of MDWCRA Maximize the weighted sum of DWC of

each ingress-egress pair after satisfying the current request

Achieve this by 1) determining appropriate weights for the links in the network and 2) route the request along the least weight path.

Algorithm Analysis

In G(V,E) Graph 1) Dijkstra Algorithm running time O(|E|log|V|) 2) Bellman-Ford Algorithm running time O(|E||V|)

Algorithm Analysis ( cont’d )

1) Calculate LPst ( for each in-egress pair O(n log n) )

2) In doing so, determine the set of critical links ( O(n) )

3) For a total of p in-egress pair , running-time is O( pn log n )

Algorithm Step1) Compute DWC value2) Compute the set of critical links

3) Compute the link weights4) Eliminate the unavailable link that is less than requested

BW5) Compute the delay-constrained least-weight path6) Route the request from a to b along this delay-

constrained least-weight path and update the residual capacities of the network

Three Definition ‘Wl’

ist

ist

ist

Clts ist

ist

l

Clts ist

l

Cltsl

DBw

Dw

w

:),(

:),(

:),(

1

1

1

Performance Comparison

Comparison ( cont’d )

Comparison ( cont’d )

Routing Bandwidth Guaranteed Paths with Restoration in Label Switched

Networks

Samphel Norden et al

Main Concept Backup Path sharing Maximize backup path sharing using BLD( Backu

p Load Distrubution ) Matrix We are focused on LSP( Label Switched Path ). This paper emphasize the point that the protocol

it suggests can be introduced in current network using OSPF extension.

Backup Mechanism

1) Backup Path with protection2) Backup Path with restorationThis paper is constrained to 2).

Backup Path sharing

u v

L1

L2

L3

1. LSP#1 is allocated link L1 as primary path and link L3 as backup path2. LSP #2 is allocated link L2 as primary path and link L3 as backup path3. LSP #2 can use L3 as Backup path for free.

State Variables CL :Link Capacity FL :the bandwidth used to primary

path GL :the bandwidth used to backup

path RL = CL – ( FL + GL )This information is maintained in

router( or in some central server )

Lack of information Assume only the three state variable ( CL ,

FL , RL ) is maintained

u v

i jLA

LB

r1(b1) = 5r2(b2) = 10r3(b3) = 12

rnew(bnew) = 33

GLB = 28RLB = 12

P1P2

P3

Lack of information( cont’d ) Route new request over LA as primary

path Select to route new request over LB as

backup path In LB how much amount can be shared?

Use of BLDM

L1

L2L3

L4 L7L5

L6

L8

P1

P2

P3 P4

Use of BLDM( cont’d )

L1

L2L3

L4 L7L5

L6

L8

B3

B2

B4

B1

BLDM BLDM[i,j] => How much amount

Link j is backed up in Link i

Benefit of BLDM

L1

L2L3

L4 L7L5

L6

L8

P1

P2

P3 P4

P5

Benefit of BLDM( cont’d )

L1

L2L3

L4 L7L5

L6

L8

P1

P2

P3 P4

P5

B5P5

Benefit of BLDM( cont’d ) P5 does not share link in primary path wit

h P2,P5 With BLDM the bandwidth of B2,B5 can b

e shared by B5 Without it, it cann’t be shared.

Example of BLDM

L1 L2 L3 L4 L5 L6 L7 L8

F 10 10 8 26 18 6 8 12

1 2 3 4 5 6 7 8

1 0 8 26 18 6 8 12

2 0 8 26

3 0 6

4 10 10 0

5 10 10 0

6 0

7 0

8 10 10 0

Mechanism of BLDM Use OSPF extension Consistency problem arises Repository node is introduced.

Free Sharable BW

L1

L2L3

L4 L7L5

L6

L8

P1

P2

P3 P4

Rnew

],[max][][ iLBLDMLGLFREE Pi

Modeling the link Cost This paper suggests the routing algorithm Until now, explain the core of the

algorithm From now, Suggests how to implement

this algorithm

Modeling the link cost(cont’d) Prefer to use free bandwidth(FR). Unless FR can support the requested BW,

should use Residual BW(R) Link Cost is modeled following our

preference.

otherwiseClFRbClFR

lFRbifClFR

lRlFRbif

lw

RF

F

,*])[(][

][)(,][

][])[(,

][

Routing Algorithm

1) Two-step algorithm2) Iterative or Enumeration based

algorithm

An Efficient QoS Routing Algorithm for Quorumcast Communication

Bin WangJeniffer C. Hou

Meaning of quorumcast Com.

A generalization of multicast communication.

In quorumcast com. We term multicast group as quorumcast pool(M).

We select quorumcast groups(Q) from quorumcast pool.

Objective Construct quorumcast routing tree that spans all

the quorumcast members and guarantee the maximum delay from source node s to any node is less than the specified value.

It is NP-Complete Problem. So Some heuristic is used

Description

(D=5,C=4)

(5,4)

(5,4)

(5,4)

(5,4)(5,4)

(5,4) (5,4)

Select n quorumcast groupfrom M quorumcast pool thatsatisfy some specification.

Network Model

REfD : REfC :

For any link, link delay and cost is defined

As previous paper, This paper describe the networkas the G(V,E)

Problem Definition

QTEl

CMQ lf )(min

subject to QvDlf dPl

D

vdsT

,)(),(

Find

Data Structures RTD

RTC

DestNode MinDelay NextHop

DestNode MinCost NextHop MinDelay-FromNextHop

Routing Algorithm(1) First, source node s initiates the route

construction process Select a node that satisfy the delay-

constraint and have minimum cost. Continues until n nodes is selected or all

nodes are marked to be included in tree.

SELECTION Data Structure Member Variable1) Cost : cost from OnTreeNode to u2) OnTreeNode : when included in the routing tre

e, the node that node u is grafted to3) Tag : whether or not node u is on the routing tr

ee.

SELECTION(cont’d) Initially ‘Cost’ is calculated from s ‘Tag’ is set to ‘NO’ ‘OnTreeNode’ is set to s

Routing Algorithm(2) After first node is chosen, first node should sele

ct the next node to be included in tree Next node is selected that has the minimum cos

t and the delay less than the specified value Iteratively, update OnTreeNode of SELECTION D

S Until all n nodes is selected, this process is rep

eated

Example

s

A

B

d3

d2

d1

(1,1)

(1,1)

(2,1)

(3,3)(1,1)

(1,1)

(0.5,0.5)

(2,1) (1,2)

Loop Detection and Removal The decision centered to Min. Cost

and or to Min. Delay can induce loop in routing tree.

Dynamic Member Join and Leave