Optical + Ethernet: Converging the Transport Network An Overview

© 2007 ADVA Optical Networking. All rights reserved. 2 Trends  R&E Optical Networks  Locally-managed fiber termination points  Locally-organized peering relationships  Locally-controlled layer-0/1/2 services  Ubiquitous Ethernet  Most-requested client service interface  Both point-to-point and virtual-LAN topologies  Apps consuming bandwidth in Ethernet-sized increments  Unit of provisioning 100/1000/10000Mbps  Options: L2 WAN, Pseudowires, Converged

© 2007 ADVA Optical Networking. All rights reserved. 3 L2 WAN  Classical Bridged Network  Transparent handoff to optical transponders  Switches establish topology at L2  Deployment issues are many  Wide-area spanning tree, ugh  Limited VLAN tag space, or go 802.1ad/ah  No Traffic Engineering, at mercy of STP = L2 switch, 802.1q/ad/ah = OADM, transponding only = Ethernet service Optical Core

© 2007 ADVA Optical Networking. All rights reserved. 4 Pseudowires  L2 Pseudowires over IP/MPLS Core  Ethernet encapsulated in IP at PE routers  Transport via IP/MPLS core, over optical WAN  VPLS-enabled Control Plane  Full mesh of MPLS LSPs, PE-to-PE  BGP/LDP assigns 802.1q flows to LSPs  Optical layer setup manually or via GMPLS = Multi-tenant unit (MTU) = OADM, transponding only = Ethernet service IP/MPLS/Optical = PE routers, MPLS Q

© 2007 ADVA Optical Networking. All rights reserved. 5 Pseudowires (cont’d)  Benefits  If IP/MPLS already built out, service type is additive  Update IP/MPLS PEs and MTUs with VPLS functionality; software for signaling, possible fw/hw for L2-in-IP encapsulation  Issues  Several distinct control mechanisms  Manual or GMPLS control plane in optical transport  IP/MPLS between PEs to establish full mesh of tunnels  LDP/BGP between PE client ports, to map pseudowires to tunnels  Management complexity  How to coordinate indications/actions/repairs across mechanisms?  Multiple encapsulations  Ethernet, into IP, into perhaps something else, into optical, and out again  Many moving parts  Control planes are complex enough, without having three of them

© 2007 ADVA Optical Networking. All rights reserved. 6 Converged  Converged Optical + Ethernet  OADMs are adding L2 functionality  Ethernet client interface, Optical transport  Unified Control Method  Optical service established via GMPLS  L2 tunnel within Optical service, also established via GMPLS (PBB-TE/GELS) = OADM q/1ad/1ah = Ethernet service Optical Core = Multi-tenant unit (MTU)

© 2007 ADVA Optical Networking. All rights reserved. 7 PBB-TE / GELS  GMPLS Control Plane for Ethernet  Ethernet as just another transport technology  VLAN or VLAN+MAC becomes the GMPLS “label”  Labels identify end-to-end path, distributed via signaling  Ethernet services become regular GMPLS tunnels  Integrates Ethernet into GMPLS management framework  Same tools (routing, signaling, pce) used by optical GMPLS  Eliminates need for other control mechanisms (RSTP, etc)  Benefits  Traffic Engineering for Ethernet – explicit control over path  Unified Control – eases coordination among layers  Automation – 802.1ad/ah forwarding tables populated via signaling rather than manually  Two methods: “short-label” and “long-label”

© 2007 ADVA Optical Networking. All rights reserved. 8 “Short Label”  Hardware  Optical DWDM transport  L2-aware client interfaces  Able to switch L2 frames between ports  Able to swap VLAN tags when transiting ports  Control Plane  Optical tunnels setup via GMPLS; label is Lambda  L2 tunnels also setup via GMPLS; label is VLAN tag  VLAN tag changes along service path – unique per-link only OADM+L2 = Optical LSP, lambda A = Optical LSP, lambda B VLAN tag X = L2 LSP, VLAN X = L2 LSP, VLAN Y + Z VLAN tag Y VLAN tag Z = swap Y for Z = add/remove VLAN

© 2007 ADVA Optical Networking. All rights reserved. 9 “Long Label”  Hardware  Optical DWDM transport  “L2-aware” client interfaces  Able to switch L2 frames between ports  Able to encapsulate MAC-in-MAC (802.1ah)  Control Plane  Optical tunnel setup via GMPLS; label is Lambda  L2 tunnel also setup via GMPLS; label is VLAN + MAC  Local L2 forwarding tables provisioned with VLAN + MAC OADM+L2 = Optical LSP, lambda A = Optical LSP, lambda B VLAN tag X = L2 LSP, VLAN X + MAC A = L2 LSP, VLAN Y + MAC B VLAN tag Y = forward per VLAN + MAC MAC B = add/remove VLAN + MAC MAC A

© 2007 ADVA Optical Networking. All rights reserved. 10 Converged Approach  Benefits  Fewer moving parts  Single element with optical transport and L2 capability  Native transport for most-requested traffic  Single, unified control mechanism across all layers  Unified control via GMPLS  Coexistence with existing 802.nnn infrastructure  No dataplane changes for long-label; ships-in-the-night with regular PBB  Traffic Engineering for Ethernet services  Explicit control over path taken; usual benefits  New deployments achieve greatest benefit; existing IP/MPLS less so  Issues  Short label requires VLAN tag swapping  Older switches may not be capable of doing this  Long label requires carrying 8-byte label in GMPLS signaling  Most implementations carry a 4-byte label; software only

© 2007 ADVA Optical Networking. All rights reserved. 11 Protocol Details  Signaling L2 Labels  Define short-label, long-label formats  Update label-related protocols objects in RSVP-TE:  Generalized Label, Label Request, Upstream Label, Suggested Label, Acceptable Label Set, Explicit Route, Record Route  TE Routing L2 Labels  Advertise L2 Label availability into OSPF-TE  Range of available VLAN tags (short-label)  VLAN+MAC pairs (long-label); under discussion  Hierarchical LSP setup  Lambda LSP setup establishes optical service  Lambda LSP forms L2SC FA-LSP, populates L2 TE database  L2 LSP paths computed on L2 TE database, established thru FA-LSP

© 2007 ADVA Optical Networking. All rights reserved. 12 References  IEEE  802.1d – STP/RSTP (2004)  802.1q – VLAN  802.1s – Multi-STP  802.1ad – PB (Q-in-Q)  802.1ah – PBB (MAC-in-MAC)  PBB-TE – under discussion  IETF  draft-fedyk-gmpls-ethernet-pbt-01 (GELS)

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