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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
