A simulation study of GELS (GMPLS-A simulation study of GELS (GMPLS-controlled Ethernet Label Switching) for controlled Ethernet Label Switching) for
Ethernet over WANEthernet over WAN
Muhammad Saqib Ilyas ([email protected])
School of Science and Engineering
LUMS, Lahore, Pakistan
IEEE Globecom 2007Washington, D.C.Wednesday, Nov 28, 2007
Work sponsored by:Siemens Corporate Technology DivisionMunich, Germany
Co-authors:Atif Nazir, Fawaz Saleem Bokhari, Zartash Afzal Uzmi (LUMS)Fahad Dogar (CMU, Pittsburgh)Adrian Farrel (Old Dog Consulting)
AgendaAgendaGMPLS – BackgroundEthernet – BackgroundGELS Architecture
◦GMPLS as the control plane for Ethernet
Simulation Modeling and SetupSimulation ResultsSummary and Conclusions
IP RoutingIP Routing
Dest: 150.10.10.1
Dest IP Next hop
I’face
………….. ….. …
150.0.0.0 ….. …
150.10.0.0
.…. …
150.10.10.0
….. …
………….. ….. …
………….. ….. …
Longest prefixmatch
Forwarding in MPLSForwarding in MPLS
Label lookup
Labeli
n
Labelou
t
I’face
… ….. …
8 8 …
9 15 …
10 13 …
… ….. …
… ….. …
Label: 10
Label: 13
MPLS challengesMPLS challengesNewer devices are capable of switching on
the basis of:◦ Interface (FSC)◦ Wavelength (LSC)◦ TDM timeslot
MPLS works with packet switch devices only◦ Looks at the label and forwards an incoming packet
Solution:◦ Generalize MPLS to GMPLS (RFC 3945)
Incompatibility of MPLS with newer devices
GMPLS offers a control plane for devices with ANY data
plane
EthernetEthernetDominant LAN transport technologySpeed and reach grew substantially
in the last 25 yearsVery flexible and cost-effective
transport
Ethernet is seeing increasing deployment in service provider networks
Ethernet in the core - Ethernet in the core - challengeschallengesExisting control plane (STP)
◦Network link utilization – Low◦Resilience mechanism – Slow◦Rudimentary support for QoS and TE
Spanning tree computed
Link failure
Spanning tree recomputed
GELS is in draft stages in IETF
No quantitative performance comparison available so far
Proposes to use GMPLS control plane for the Ethernet data plane!
GELSGELS
Ethernet Bridge
Our workOur workSimulation based evaluation of
GELSRapid STP (RSTP) versus GMPLS
◦How does old control plane compare with new control plane?
Considered:1.Normal network operation2.Single element failures
GELS Recovery Schemes
Evaluation CriteriaEvaluation CriteriaHow efficiently can we use the
network?
How quickly can we recover from
failure?
GMPLS with Compromised CSPF
Evaluation challengesEvaluation challengesHow to compare contention-based
Ethernet with reservation based GMPLS?◦Allow partial placement of LSPs in GMPLS
instead of YES/NO placement
Request: 25Placed: 0
GMPLS with CSPF
Placed: 15
LSP placedBandwidth placed: 60%LSP not placedBandwidth placed: 0%
Capacity: 100
Available: 15
Available: 0
Switch traffic onto new LSP
tsw: Switching delay
GELS: Convergence timeGELS: Convergence time
Link failure
Failure notification
sent to ingresstsig: Signaling
delay
Compute new LSP
tproc: Processing delay
Potential new path
Reserve new LSPtres: Reservation
delay
Ingress Egres
s
LSP
Restoration: trest = tsig + tproc + tres + tsw
Protection: tprot = tsig + tsw
Nearest upstream
node to the failure
Timing parameter valuesTiming parameter values
tsig(Signaling delay):
◦ Based on 1ms/200 km link propagation delay
tproc(Processing delay):
◦ 5ms
tres(Reservation delay):
◦ Based on 1ms/200 km link propagation delay
tsw(Switching delay):
◦ 1ms
GELS restoration recovery GELS restoration recovery timetime
LSP 1LSP 2
Ingress has lost multiple LSPs
Nearest upstream
node for LSP 2
Nearest upstream
node for LSP 1
Failure signaled to
ingress
Link failure
1. Compute
2. Reserve3. Switch
SequentiallyOr
In parallel
Sequentially
Sequentially
Convergence time is
tmin
Convergence time is
tmax
Simulation setup - Simulation setup - networksnetworks
Milan (11)
Copenhagen (1)
London (2) Amsterdam (3) Berlin (4)
Brussels (5) Luxembourg (6) Prague (7)
Paris (8) Zurich (9) Vienna (10)
Oslo (2)Helsinki (1)
Stockholm (3)
Glasgow (4)
Copenhagen (6)
Dublin (7)
Birmingham (9)
London (10)
Amsterdam (11)Hamburg (12)Berlin (13) Warsaw (14)
Brussels (15)Dusseldorf (16)
Frankfurt (17)
Paris (19)Strasbourg (20)Munich (21)
Prague (22)
Krakow (23)
Zurich (26) Vienna (24)
Budapest (28)
Bordeaux (30) Lyon (31)Milan (32) Zagreb (33)
Belgrade (37)
Marseille (42)
Barcelona (41)Sofia (46)
Lisbon (43)Madrid (44)
Rome (45)
Seville (47)Palermo (49)
Athens (50)
Turin (35)Porto (39)Bukarest (38)
Neapel (48)
Belfast (5)
Graz (29)
Basel (25)
Toulouse (34)
Salzburg (27)
Liverpool (8)
Zaragoza (40)Bologna (36)
Leipzig (18)
COST 239: 11 nodes
COST 266: 50 nodes
Traffic matricesTraffic matricesLSP requests arrive one-by-oneRandomly chosen ingress and
egress nodesBandwidth request 1, 2 or 3 Gb/s
chosen with equal probability
Simulation environmentSimulation environmentBased on:
◦Bridgesim1 for native Ethernet◦TOTEM2 for GMPLS-controlled
EthernetEnhancements to simulators:
◦Implementation of C-CSPF◦Computation of recovery time
1: http://www.cs.cmu.edu/~acm/bridgesim/index.html2: http://totem.info.ucl.ac.be/
Results: LSP placement Results: LSP placement percentagepercentageGELS with restoration places more LSPs than RSTP
GELS with protection places fewer LSPs than RSTP
Results: Bandwidth Results: Bandwidth placementplacement
GELS with protection places less (primary) bandwidth than RSTP
GELS with restoration places more bandwidth than RSTP
Results: Average link Results: Average link utilizationutilization
RSTP has lowest average link utilization
GELS with protection quickly approaches almost full link utilization GELS approaches 92% average
link utilization
Results: RSTP convergence time vs cost Results: RSTP convergence time vs cost to rootto root
RSTP convergence time is highest if the root bridge fails
Convergence time decreases as cost to root increases
Single link failure average convergence time
Topology
RSTP (ms)
Restoration (ms) Protection (ms)tmin tmax
11 nodes
0.7 32.67 41.61 3.89
50 nodes
102.4 38.13 39.61 6.18
Results: Single link failure Results: Single link failure convergence timeconvergence time
More links closer to root bridge in COST 266More LSPs were restored in COST
239
Single link failure average convergence time
Topology
RSTP (ms)
Restoration (ms) Protection (ms)tmin tmax
11 nodes
4850 30.07 39.34 2.56
50 nodes
3365 42.25 44.24 6.1
Results: Node failure Results: Node failure convergence timeconvergence time
t1 - t10 are in milliseconds
10
1iit
t1 – t49 are in milliseconds
50+
11
Small value
10
1iit50+
50
Small value
SummarySummaryAbout 45% improvement with
GELS over native Ethernet in: ◦LSP acceptance◦Bandwidth placement
Failure recovery time orders of magnitude less for GELS than for native Ethernet
ConclusionConclusionEthernet is a flexible, cost effective
and efficient transport mechanism for metro/core networks
GMPLS promises to be a useful control plane for Ethernet in metro/core
Tremendous administrative benefits of using a single control plane
Vendors actively working on standardization of GELS
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