Optical + Ethernet: Converging the Transport Network. An Overview

Transcription

1 Optical + Ethernet: Converging the Transport Network An Overview

2 Trends Regional Optical Networks for Research 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 Dynamic Provisioning User requirements constantly changing, growing Reconfigurability, to facilitate Research mission 2

3 User View Network == One Big Optical+Ethernet Switch Site A Site C Site B Site D 3

4 Why Optical+Ethernet Economics Ethernet an extremely cost-effective platform Rich LAN technology ecosystem, leveragable in WAN Simplicity Layer elimination; less encapsulation, simpler control One transport (optical), one client interface (Ethernet) Single control plane for both technologies Flexibility Strong standards base ensures interoperability Technology easily adapted to broad application base Dynamic control plane automates provisioning/monitoring 4

5 Transport Technologies Ethernet Lambda Fiber Lambda Ethernet 5

6 Technologies Ethernet WAN Classic stretched to the WAN Ethernet frames switched according to Spanning Tree VPLS Virtual Private Line/LAN Service Ethernet frames encapsulated in IP/MPLS pseudowires T-MPLS ITU-T profile of MPLS data plane Ethernet frames switched according to MPLS label PBT / PBB-TE 802.1ad/ah with Traffic Engineering Ethernet frames switched according to native VLAN/MAC 6

7 Ethernet WAN Optical Core Classical Bridged Network PB/PBB switches handle both data and control Transparent handoff to optical transponders Mixed Control Methods Optical setup manually or via GMPLS L2 bridging at switches, STP/RSTP over WAN = PB/PBB, 802.1q/1ad/1ah = OADM, transponding only = Ethernet service 7

8 Ethernet WAN (cont d) Upsides Simple Devices Only switches and transport elements required One L2 control mechanism Downsides 802.1Q tagging, 802.1ad/ah for PB/PBB Spanning Tree in the WAN Long convergence/restoration times, even with RSTP No control over tree root, suboptimal paths, etc; usual complaints No Traffic Engineering STP does not consider link availability/loading, other factors No explicit path control, no diversity control, no fate sharing control Limited VLAN tag space Max 4094 VLANs, or complex, manual 802.1ad/1ah configurations Bottom Line Classic LAN control does not scale well to the WAN 8

9 Pseudowires IP/MPLS/Optical L2 Pseudowires over IP/MPLS Core Ethernet encapsulated in IP at PE routers Tansport 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 = PE routers, VPLS Q = Multi-tenant unit (MTU) = OADM, transponding only = Ethernet service 9

10 Pseudowires (cont d) Benefits If IP/MPLS already built out, service type is additive Issues Update IP/MPLS PEs and MTUs with VPLS functionality; software for signaling, possible fw/hw for L2-in-IP encapsulation 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 Bottom Line Many moving parts, many encapsulations, hardware-intensive Control planes are complex enough, without having three of them 10

11 T-MPLS T-MPLS Ethernet transport over (T-)MPLS Core MPLS labels applied to Ethernet frames Label-Switch-capable elements, plus transport Switched as usual MPLS payload Optional Control Plane T-MPLS does not specify any control plane, though anticipates use of GMPLS = LS element with T-MPLS = Ethernet Switch = OADM, transponding only = Ethernet service 11

12 T-MPLS (cont d) Benefits Aligns classic MPLS with existing ITU-T Recommendations Improved OA&M for strict connection-oriented networks Allows for unified control plane solution via GMPLS Issues Removes various MPLS functionality; interworking? Removes penultimate hop-popping Removes Equal Cost Multiple Path (ECMP) Removes LSP merge Focuses on strict OA&M; strong requirement outside carriers? Clients pursuing Ethernet economics, OA&M not my problem Equipment must do label application/processing Ethernet already has strong switching; VLANs, MAC/MAC, etc Gear now must also switch using MPLS labels; complexity Bottom Line Adoption/interest unclear outside carriers Control plane can be unified, though optional 12

13 PBT / PBB-TE Optical Core Converged Optical+Ethernet OADMs add L2 functionality Ethernet client interface, Optical transport Unified Control Plane Optical service established via GMPLS L2 service within Optical service, also established via GMPLS (GELS) = OADM q/1ad/1ah = Multi-tenant unit (MTU) = Ethernet service 13

14 GELS GMPLS-controlled Ethernet Label Switching 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 14

15 PBT / PBB-TE (cont d) 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 infrastructure No dataplane changes for long labels, ships-in-the-night with regular PBB Traffic Engineering for Ethernet services Explicit control over path taken; usual benefits New deployments achieve greatest benefit Issues Short label requires VLAN tag swapping Older switches may not be capable of doing this Bottom Line Unified Optical+Ethernet is a reality 15

16 Short Label OADM+L2 OADM+L2 OADM+L2 VLAN tag Y VLAN tag Z OADM+L2 VLAN tag X OADM+L2 OADM+L2 Hardware Optical DWDM transport L2-aware client interfaces Able to switch L2 frames between ports Able to swap VLAN tags when transiting ports = Optical LSP, lambda A = Optical LSP, lambda B = L2 LSP, VLAN X = L2 LSP, VLAN Y + Z = swap Y for Z = push/pop VLAN 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 16

17 Long Label OADM+L2 OADM+L2 OADM+L2 VLAN tag Y OADM+L2 MAC B VLAN tag X OADM+L2 OADM+L2 Hardware MAC A Optical DWDM transport L2-aware client interfaces Able to switch L2 frames between ports Able to encapsulate MAC-in-MAC (802.1ah) = Optical LSP, lambda A = Optical LSP, lambda B = L2 LSP, VLAN X + MAC A = L2 LSP, VLAN Y + MAC B = forward per VLAN + MAC = wrap/unwrap VLAN + MAC 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 17

18 Unified Control Plane Client Clients see LAN-style interfaces Ethernet Ethernet VLANs established via GMPLS signaling, inner tunnels DWDM Optical channels established via GMPLS signaling, outer tunnels 18

19 Comparisons Encapsulation Standardization = Ethernet WAN = T-MPLS = Pseudowires = PBB-TE / GELS 19

20 Comparisons (cont d) Control Capability Control Complexity = Ethernet WAN = T-MPLS = Pseudowires = PBB-TE / GELS 20

21 LAN Emulation Ethernet Ethernet A DWDM C B D Point-to-Multipoint GELS Use GMPLS to establish Optical tunnel Usual stuff Use GELS to establish LAN emulation Point-to-Multipoint LSPs from each endpoint Again, VLANs provisioned automatically User sees single LAN containing 4 endpoints Still some standardization required Point-to-multipoint Traffic Engineering = DWDM Ring = Provision Lambda = Provision VLAN+DMAC 21

22 Ring Interconnect Ethernet Ethernet DWDM DWDM DWDM = DWDM Ring = Native L2 Links = Provision Lambda = Provision VLAN+DMAC 22

23 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) 23

24 Thank You