MPLS over Optical Ethernet: Reliability and Traffic Engineering Performance

1. MPLS over Optical Ethernet: Reliability and Traffic Engineering Performance F. Cugini, L. Valcarenghi, P. Castoldi Scuola Superiore Sant’Anna (SSSUP) Cannes (Fr), September 27, 2006

2. Introduction • Optical Ethernet (OE) architectures represent a simple and low cost solution suitable for Metropolitan Area Networks (MAN). • The limiting factor for the widespread deployment of OE architectures is the lack of some OA&M features, such as resilience and efficient Traffic Engineering (TE). • MPLS can be utilized to improve the OE performance • Here we present: • Overview of OE recovery schemes • Experimental evaluation of MPLS over OE recovery schemes* • A proposal for joint activity focused on Traffic Engineering in MPLS over OE metro networks * e-Photon/One SSSUP – AGH – FUB collaboration

3. Optical Ethernet Resilience(1) Rapid Spanning Tree Protocol (RSTP) • 802.1d Spanning Tree (STP) acts at layer 2, taking about 50 sec to recover from failures. • 802.1w Rapid STP (RSTP) is an evolution of STP (backward compatibility is guaranteed). • RSTP allows pre-computed backup ports on Bridges: when a failure occurs, if the backup port is in Forwarding State, the physical connectivity can be restored in 10msec (best case). • However in some cases [1], failure recovery may require more than hundreds of msec. [1] E.Sfeir et al. “Performance Evaluation of Ethernet Resilience Mechanisms”, HPSR 2005

4. Optical Ethernet Resilience(2) Resilient Packet Ring (RPR) • New MAC protocol (Layer 2 technology) • Restoration within 50 msec • Steering(all stations are notified of the entire topology and of the failure location: the transmitting stations choose the ringlet that does not contain the failure) • Wrapping (station adjacent the failure wraps traffic to other ringlet) Customer Premises CO • Requires specific network topology (ring) • Not supported by most of equipments

5. Customer Premises CO Optical Ethernet Resilience(3) Hub and Spoke design • Every Optical Ethernet (OE) connection is protected with a dedicated point-to-point link. • Besides the fiber availability it requires the presence of many OE interfaces in the Central Office. • Not cost effective

6. LB 5 LB 6 LB 3 10.0.0.3 LB 4 10.0.0.4 LB 1 10.0.0.1 Control Plane LB 2 10.0.0.2 PXC 5 Router C Router D PXC 6 PXC 3 PXC 4 Data PXC 1 PXC 2 Router A Router B Optical Ethernet Resilience(4) Layer1-based recovery schemes* • Exploits low-cost optical switches and GMPLS signaling • Failure detection based on Loss of Light • An outage time of less than 5 ms has been observed * e-Photon/One SSSUP

7. LSR Source LSR Dest Optical Ethernet Resilience (5) MPLS-based recovery schemes* • MPLS-based recovery schemes require support of • MultiProtocol Label Switching (MPLS) • Open Shortest Path First (OSPF) • Reservation Protocol (RSVP) • Current Layer 3 switches fully support the above protocols. * e-Photon/One SSSUP – AGH – FUB collaboration

8. 1 2 6 5 3 4 PATH ERR RESV TEAR RESV PATH PATH TEAR PATH TEAR LSR Source MPLS recovery schemes (1) path restoration • Backup path not established in advance • One single entry in the forwarding table • Measured recovery time: 60-80 ms

9. 1 2 6 5 3 4 PATH ERR RESV TEAR RESV Refresh PATH Refresh PATH TEAR PATH TEAR LSR Source MPLS recovery schemes (2) path protection • Backup path established in advance • Two entries in the forwarding table • Measured recovery time: 10-20 ms

10. PATH + Detour obj. PATH + FR obj. PATH + FR obj. PATH + FR obj. MPLS recovery schemes (3) fast reroute • Detour paths are established in advance • Two more RSVP-TE objects are included in the PATH messages: Fast Reroute and Detour • Measured recovery time: • max 11ms, typical 2ms, min 0.6ms LSR Source

11. Considerations • The availability of low-cost Optical Ethernet (OE) networks has extended the use of Ethernet outside the LAN. • OE architectures allow to remove the expensive ring-based SDH infrastructure in favour of a more flexible and reconfigurable cost-effective mesh network. • MPLS over OE  efficient failure recovery • Moreover, MPLS over OE allows: - optimal Traffic Engineering solutions (in the case of both single and multi routing Area)  efficient allocation of bandwidth guaranteed services. - different metro network topology design, i.e. considering not only ring and hub-and-spoke network topologies.

12. Proposal for Joint Research Activity (1/3) • Title: “High Quality applications in Multi-Vendor Multi-Area MPLS Metro networks” • The objective is to perform theoretical and experimental studies on the possible approaches to efficiently provide Quality of Service (QoS) to high performance applications such as High Definition Television (HDTV) and bandwidth guaranteed network services in OE-based metro networks • The network scenario includes commercial IP/MPLS switches/routers manufactured by different vendors.

13. Proposal for Joint Research Activity (2/3) • The activity plan covers interoperability analysis in single Open Shortest Path First (OSPF) Area with a special focus on the set up of dynamic bandwidth guaranteed connections for high quality applications. • The research activity then foresees experimentation and theoretical studies in the context of multi-Area OSPF networks. • In particular Traffic Engineering (TE) solutions provided by both distributed and centralized network elements will be investigated in order to guarantee the required level of QoS to the applications. • Metro Topology design will be also considered, taking into account the low level of grooming, the asymmetry of traffic matrices and the presence of high quality application services.

14. Proposal for Joint Research Activity (3/3) • Participants: • New partners are welcome.. • We encourage the exchange of students and researchers • SSSUP • Contacts: • Filippo Cugini (filippo.cugini@cnit.it) • Piero Castoldi (castoldi@sssup.it) • FUB • Contacts: • Luca Rea (lrea@fub.it) • Francesco Matera (mat@fub.it)