1. A simulation study of GELS (GMPLS-controlled Ethernet Label Switching) for Ethernet over WAN Muhammad Saqib Ilyas (msaqib@ieee.org)msaqib@ieee.org School of Science and Engineering LUMS, Lahore, Pakistan IEEE Globecom 2007 Washington, D.C. Wednesday, Nov 28, 2007 Work sponsored by: Siemens Corporate Technology Division Munich, Germany Co-authors: Atif Nazir, Fawaz Saleem Bokhari, Zartash Afzal Uzmi (LUMS) Fahad Dogar (CMU, Pittsburgh) Adrian Farrel (Old Dog Consulting)

2. Agenda GMPLS – Background Ethernet – Background GELS Architecture ◦ GMPLS as the control plane for Ethernet Simulation Modeling and Setup Simulation Results Summary and Conclusions

3. IP Routing Dest: 150.10.10.1 Dest IPNext hop I’face …………..…..… 150.0.0.0…..… 150.10.0.0.….… 150.10.10.0…..… …………..…..… …………..…..… Longest prefix match

4. Forwarding in MPLS Label lookup Label in Label out I’face ……..… 88… 915… 1013… ……..… … … Label: 10 Label: 13

5. MPLS challenges Newer 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

6. Ethernet Dominant LAN transport technology Speed and reach grew substantially in the last 25 years Very flexible and cost-effective transport Ethernet is seeing increasing deployment in service provider networks

7. Ethernet in the core - challenges Existing control plane (STP) ◦ Network link utilization – Low ◦ Resilience mechanism – Slow ◦ Rudimentary support for QoS and TE Spanning tree computed Link failure Spanning tree recomputed

8. 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! GELS Ethernet Bridge

9. Our work Simulation based evaluation of GELS Rapid STP (RSTP) versus GMPLS ◦ How does old control plane compare with new control plane? Considered: 1.Normal network operation 2.Single element failures

10. GELS Recovery Schemes Evaluation Criteria Evaluation criteria Normal network condition Average link utilization Number of LSPs placed Total bandwidth placed Failed network condition Single link failure Single node failure RSTP convergence time GELS recoveryRestorationProtection How efficiently can we use the network? How quickly can we recover from failure?

11. GMPLS with Compromised CSPF Evaluation challenges How to compare contention-based Ethernet with reservation based GMPLS? ◦ Allow partial placement of LSPs in GMPLS instead of YES/NO placement Request: 25 Placed: 0 GMPLS with CSPF Placed: 15 LSP placed Bandwidth placed: 60% LSP not placed Bandwidth placed: 0% Capacity: 100 Available: 15 Available: 0

12. Switch traffic onto new LSP t sw : Switching delay GELS: Convergence time Link failure Failure notification sent to ingress t sig : Signaling delay Compute new LSP t proc : Processing delay Potential new path Reserve new LSP t res : Reservation delay Ingress Egress LSP Restoration: t rest = t sig + t proc + t res + t sw Protection: t prot = t sig + t sw Nearest upstream node to the failure

13. Timing parameter values t sig (Signaling delay): ◦ Based on 1ms/200 km link propagation delay t proc (Processing delay): ◦ 5ms t res (Reservation delay): ◦ Based on 1ms/200 km link propagation delay t sw (Switching delay): ◦ 1ms

14. GELS restoration recovery time LSP 1 LSP 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.Reserve 3.Switch Sequentially Or In parallel Sequentially Convergence time is t min Convergence time is t max

15. Simulation setup - networks Milan (11) Copenhagen (1) London (2)Amsterdam (3)Berlin (4) Brussels (5)Luxembourg (6)Prague (7) Paris (8)Zurich (9)Vienna (10) COST 239: 11 nodesCOST 266: 50 nodes

16. Traffic matrices LSP requests arrive one-by-one Randomly chosen ingress and egress nodes Bandwidth request 1, 2 or 3 Gb/s chosen with equal probability

17. Simulation environment Based on: ◦ Bridgesim 1 for native Ethernet ◦ TOTEM 2 for GMPLS-controlled Ethernet Enhancements to simulators: ◦ Implementation of C-CSPF ◦ Computation of recovery time 1: http://www.cs.cmu.edu/~acm/bridgesim/index.html 2: http://totem.info.ucl.ac.be/

18. Results: LSP placement percentage GELS with restoration places more LSPs than RSTP GELS with protection places fewer LSPs than RSTP

19. Results: Bandwidth placement GELS with protection places less (primary) bandwidth than RSTP GELS with restoration places more bandwidth than RSTP

20. Results: Average link utilization RSTP has lowest average link utilization GELS with protection quickly approaches almost full link utilization GELS approaches 92% average link utilization

21. Results: RSTP convergence time vs cost to root RSTP convergence time is highest if the root bridge fails Convergence time decreases as cost to root increases

22. Single link failure average convergence time TopologyRSTP (ms) Restoration (ms)Protection (ms) t min t max 11 nodes0.732.6741.613.89 50 nodes102.438.1339.616.18 Results: Single link failure convergence time More links closer to root bridge in COST 266 More LSPs were restored in COST 239

23. Single link failure average convergence time TopologyRSTP (ms) Restoration (ms)Protection (ms) t min t max 11 nodes485030.0739.342.56 50 nodes336542.2544.246.1 Results: Node failure convergence time t 1 - t 10 are in milliseconds t 1 – t 49 are in milliseconds 50+ 11 Small value 50+ 50 Small value

24. Summary About 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

25. Conclusion Ethernet 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

26. Questions? Contact: msaqib@gmail.com Simulator: http://suraj.lums.edu.pk/gels/