Ethernet vs-mpls-tp-in-the-access-presentation

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A presentation given by RAD’s CTO, Dr. Yaakov Stein, at the 2012 MPLS and Ethernet World Congress. The presentation compares the two technologies in ten critical categories and grades them on suitability, coverage and maturity

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Ethernet vs-mpls-tp-in-the-access-presentation

  1. 1. Ethernet vs. MPLS-TPin Access NetworksYaakov (J) SteinCTORAD Data Communications Ethernet vs. MPLS-TP in the Access Slide 1
  2. 2. AgendaIs MPLS-TP ready to replace Ethernet as the packet technologythat dominates access networks?• Brief review of access networks• Characteristics of Ethernet and MPLS-TP• Technical comparison: Ethernet vs. MPLS-TP Ethernet vs. MPLS-TP in the Access Slide 2
  3. 3. Access Networks Ethernet vs. MPLS-TP in the Access Slide 3
  4. 4. Access Network Considerations Residential Customers (IP) Access Network: Core: Q-in-Q Ethernet? MPLS or IP Business Customers interface (IP or Ethernet) MPLS-TP ? (and theoretically PBB) Cell Sites (IP and/or Ethernet and/or TDM Other Data Other Internet Centers and Timing) customer customer sites sites Ethernet vs. MPLS-TP in the Access Slide 4
  5. 5. Why Ethernet and MPLS-TP ? First Mile Customer Core Network: Access Network Network: Ethernet MPLS Last Mile • Ethernet started in customer networks (LAN) and over the years has moved into the access network (MEF) • MPLS started in the core network and is now trying to conquer the access network Ethernet vs. MPLS-TP in the Access Slide 5
  6. 6. Access Network Segmentation First/Last Mile Middle Mile NTU/CLE Access Node + Aggregation Backhaul Access NetworkA recent trend is to segment the access network into:• First/Last Mile – Provides connectivity from customer site to first access node – Leverages physical layer technologies such as DSL, active/passive fiber, microwave, HSDPA+, LTE, …• Middle Mile – Collects and aggregates traffic from multiple access nodes – Provides backhaul towards core Ethernet vs. MPLS-TP in the Access Slide 6
  7. 7. Access / Core Differences (1)Differences between core and access networks may translate toprotocol requirements differences: Core Access Impact No. of Few – routers, Many – CPEs, NTUs, • Strong pressure on Network LSRs, switches DSLAMs, access NE price levels Elements aggregators • Access needs to be as “touchless” as possible Data Rates Higher Lower • Core may guarantee QoS by resource over-provisioning • Access needs QoS mechanisms Ethernet vs. MPLS-TP in the Access Slide 7
  8. 8. Access / Core Differences (2) Core Access ImpactTopology Richly connected Simple – typically • Fault in access network trees or rings affects fewer people, but fewer bypass options • Core can get away with fast rerouting • Access network requires OAM and planned APSSecurity “Walled garden”: Easily accessible • Customer networks also • Strong security considered walled gardens to and from • Impractical to protect the the outside entire access network world • Loose security on the inside Ethernet vs. MPLS-TP in the Access Slide 8
  9. 9. Ethernet and MPLS-TPOverview Ethernet vs. MPLS-TP in the Access Slide 9
  10. 10. Ethernet / MPLS-TP Differences (1)While both Ethernet and MPLS are commonly used to carry IP,there are some fundamental protocol differences: Ethernet MPLS-TP OSI Layer L0-L2 Requires a server layer to (but may run over MPLS) transport it (which may be Ethernet) Packet Frames are inherently No PID Identification self-describing Scope Destination address: Only locally-meaningful labels Global, not aggregated Source Unique source address No source identifier Identifier Clients IP and other IP and other Transport Over SDH/SONET, OTN Over SDH/SONET, OTN Ethernet vs. MPLS-TP in the Access Slide 10
  11. 11. Ethernet / MPLS-TP Differences (2) Ethernet MPLS-TPOAM and • Fault Management • Fault ManagementProtection • Performance Monitoring • Performance Monitoring • APS • APSIP Protocols • No routing protocol Leverages the entire IP suite defined of protocols • A number of L2CPsLoop No Can tolerate transient loopsTolerance (has TTL field)Priority • 3-bit (e.g., DiffServ) 3-bit (DiffServ)Marking • “Drop Eligibility”Additional • Bandwidth Profiles None have been definedDedicated • Timing over PacketTools • Security (MACSec)Developed By • IEEE • IETF • Multiple competing SDOs • Multiple competing SDOs Ethernet vs. MPLS-TP in the Access Slide 11
  12. 12. Ethernet and MPLS-TP:Face-Off Ethernet vs. MPLS-TP in the Access Slide 12
  13. 13. Comparison Criteria1. Fault Management Functionality2. Performance Management Functionality3. Automatic Protection Switching Mechanisms4. Quality of Service Mechanisms Each will be scored for:5. Traffic – Handling Diverse Client Types Suitability: 2 points6. Timing – High Accuracy Time and Coverage: 4 points Frequency Distribution Maturity: 4 points7. Integration with Surrounding Networks8. CapEx9. OpEx10. Security Ethernet vs. MPLS-TP in the Access Slide 13
  14. 14. Fault Management Functionality:The ArgumentsThe Need: Access networks require strong FM capabilities to minimize down-time Ethernet • Two OAM mechanisms (Y.1731/CFM and EFM) • Unique source address, particularly amenable to trace-back functionality • Q-in-Q is not true client-server, but this is covered up by MEL • Y.1731 is full-featured – comprehensive set of FM TLVs • EFM is more limited, but adds dying gasp critical for CPEs • Interop issues of both OAMs have finally been resolved; remaining details are resolved via implementation agreements (e.g., MEF-30)MPLS-TP• Had basic heartbeats (BFD) and diagnostics (LSP-ping)• The IETF designed MPLS-TP FM based on the Generic Access Channel and: • BFD for CC • LSP-ping for on-demand diagnostics • New frame formats to fulfill specific requirements Ethernet vs. MPLS-TP in the Access Slide 14
  15. 15. Fault Management Functionality:The Verdict Ethernet MPLS-TP No true address, requires Highly suited (SA) Suitability extra work 2 Points 1 Point Y.1731 is full featured, EFM MPLS-TP FM similar to CFM Coverage fulfills its requirements but missing dying gasp 4 Points 3 Points Y.1731 and EFM are Some MPLS-TP features are interoperable and widely seeing initial trials Maturity deployed 4 Points 1 Point Total 10 Points 5 Points Ethernet vs. MPLS-TP in the Access Slide 15
  16. 16. Performance Management Functionality:The Arguments The Need: Useful tool for maintenance and diagnostics of the access network Ethernet • The ITU Y.1731 supports PM (loss, delay, PDV, …) using a request-response model; IEEE 802.1ag does not • Y.1731 is used as the basis for commissioning procedures (Y.1564) • Widespread vendor interoperability has been demonstrated MPLS-TP • RFCs 6374, 6375 define a set of PM functions based on the GA Channel • These functions were designed to be HW friendly, yet flexible - Support byte or packet counters - 1588 or NTP-style timestamps - Traffic-counters or synthetic loss • Implementations have yet to be announced Ethernet vs. MPLS-TP in the Access Slide 16
  17. 17. Performance Management Functionality:The Verdict Ethernet MPLS-TP Neither protocol has an inherent advantage or disadvantage Suitability 2 Points 2 Points Supports all features (may Supports all features Coverage be more flexible) 4 Points 4 Points MPLS PM is not (widely) Y.1731 is finally interoperable Maturity implemented 4 Points 0 Points Total 10 Points 6 Points Ethernet vs. MPLS-TP in the Access Slide 17
  18. 18. Automatic Protection Switching:The ArgumentsThe Need: APS is a complex subject, requiring careful protocol work and proper configuration. Solutions required for both linear and ring protectionEthernet• Ethernet has a particular problem with rings• There are many open loop ring protection (e.g., G.8032) but these are not compatible with QoS mechanismsMPLS-TP• MPLS in the core exploits Fast ReRoute (RFC 4090) instead of APS • But FRR requires rich interconnection and so is usually not applicable to access networks• The IETF has standardized RFC 6378 for MPLS-TP linear protection • There are also proposals for ring protection Ethernet vs. MPLS-TP in the Access Slide 18
  19. 19. Automatic Protection Switching:The Verdict Ethernet MPLS-TP No particular strengths or Not suitable for ring protection Suitability weaknesses 0 Points 2 Points G.8031/G.8032 fulfill current RFC 6378 (linear protection); Coverage requirements no ring protection RFC yet 3 Points 2 Points G.8031/G.8032 have been MPLS-TP only partially extensively debugged and finalized and not yet Maturity updated deployed 4 Points 1 Point Total 7 Points 6 Points Ethernet vs. MPLS-TP in the Access Slide 19
  20. 20. Quality of Service:The ArgumentsTwo types of QoS need to be considered to manipulate traffic:1. Hard QoS (engineering): Connection Admission Control, Resource Reservation2. Soft QoS (conditioning): Priority marking, discard eligibility, queuing, bucketing Ethernet • PBB-TE (PBT) defines hard QoS, but is not widely implemented • P-bits for prioritization marking; discard eligibility marking in S-VLANs • MEF’s BW profile defines a bucketing algorithm • Ethernet headers are self-describing – support Traffic Awareness MPLS-TP • MPLS-TE supports resource reservation but traffic engineering may not be relevant for access networks • Traffic Class (and L-LSPs) support DiffServ prioritization application awareness – MPLS packets are not self-describing • DPI is required for Traffic Awareness Ethernet vs. MPLS-TP in the Access Slide 20
  21. 21. Quality of Service:The Verdict Ethernet MPLS-TP Does not define for (bucket- Supports all QoS types Suitability based) traffic conditioning 2 Points 1 Point MEF standards have been Without bucketing, Coverage proven MPLS is at a disadvantage 4 Points 3 Points BW profiles are standardized; MPLS-TP – nothing special Maturity certification programs 4 Points 0 Points Total 10 Points 4 Points Ethernet vs. MPLS-TP in the Access Slide 21
  22. 22. Traffic types:The ArgumentsThe Need: No transport protocol is useful if it can’t transport the required client traffic Ethernet • Differentiates traffic via Ethertype marking or LLC • Can directly carry IPv4, IPv6, MPLS, Ethernet, fiber channel, and low- rate TDM (MEF-8) • Does not directly carry other legacy traffic types (e.g., ATM, frame relay) • Can be carried indirectly via PHP’ed MPLS PWs MPLS-TP • Can carry IPv4, IPv6, MPLS, and PWs (and through which Ethernet, Fiber Channel and all legacy types) • Defining a new PW type requires IETF consensus but the new packet-PW provides more freedom Neither is universal but existing mechanisms can be extended to cover new cases Ethernet vs. MPLS-TP in the Access Slide 22
  23. 23. Traffic types:The Verdict Ethernet MPLS-TP Supports arbitrary clients via Supports arbitrary clients via Suitability Ethertypes PWs 2 Points 2 Points Does not support all legacy Supports most traffic types Coverage traffic types (ATM, FR) via PWs 2 Points 3 Points Ethertypes have been widely PWs have been widely Maturity deployed deployed 4 Points 4 Points Total 8 Points 9 Points Ethernet vs. MPLS-TP in the Access Slide 23
  24. 24. Timing:The ArgumentsThe Need: Distribution of highly accurate timing (frequency and Time of Day) is crucial for some access network applications, notably cellular backhaulEthernetTwo protocols have become standard for this purpose:1. Synchronous Ethernet (SyncE) is Ethernet-specific2. IEEE 1588-2008 (defined for Ethernet and UDP/IP) for Timing over Packet; on-path support elements (Boundary Clocks or Transparent Clocks) have only been defined for EthernetMPLS-TP• MPLS does not define a physical layer• The IETF TICTOC WG is presently working on 1588oMPLS Ethernet vs. MPLS-TP in the Access Slide 24
  25. 25. Timing:The Verdict Ethernet MPLS-TP May be able to support Supports ToP and defines a 1588 but there can be no Suitability physical layer to support SyncE SyncMPLS 2 Points 1 Point Meets all requirements with 1588oMPLS to support ToP Coverage SyncE, 1588, BC, TC may be coming 4 Points 1 Point ITU-T has defined profile(s) for MPLS presently has no Maturity 1588 use timing support 4 Points 0 Points Total 10 Points 2 Points Ethernet vs. MPLS-TP in the Access Slide 25
  26. 26. Integration:The ArgumentsThe access network needs to integrate with the core and customer networks.Cost and complexity will be minimized by a smooth hand-off, i.e., accessprotocol compatibility with other network protocols• Customer networks may have Ethernet or TDM interfaces (IP over Ethernet, Ethernet over TDM, Ethernet over SDH)• Core networks are usually MPLS (IP over MPLS, MPLS over Ethernet, MPLS over SDH) Ethernet • Ethernet in the access is a perfect match for customer networks • Can not seamlessly interface with MPLS core MPLS-TP • A reasonable match for customer network protocols since they can be tunneled over MPLS • Reuses existing MPLS standards thus maximizing compatibility Ethernet vs. MPLS-TP in the Access Slide 26
  27. 27. Integration:The Verdict Ethernet MPLS-TP Best match for core Perfect match for customer network, but not for Suitability network, but not for core customer 1 Point 1 Point Does not require GW for Ethernet Q-in-Q and MAC-in- forwarding to core, but MAC perfect customer hand- Coverage control protocols may not off interconnect 3 Points 2 Points Ethernet Q-in-Q presently Seamless MPLS still in its Maturity widely deployed infancy 4 Points 1 Point Total 8 Points 4 Points Ethernet vs. MPLS-TP in the Access Slide 27
  28. 28. CapEx:The ArgumentsThe Need: Access network providers need to keep their costs down; due to thelarge number of Network Elements, access networks are CapEx-sensitive Ethernet • Ethernet switching fabrics are inherently non-scalable (long global addresses can’t be aggregated) • Due to popularity, Ethernet switches are inexpensive (high volumes, large R&D investment in cost reduction) • However, carrier-grade Ethernet switches need extra functionality • Ethernet supports CapEx-saving architectures (e.g., EPON) MPLS-TP • LSRs are complex and expensive – reducing the price of NEs (MPLS switch instead of MPLS router) was the unstated motivation for MPLS-TP • Pure MPLS NEs have simple forwarding engines and thus should be less expensive than Ethernet switches, but still require Ethernet or SDH or OTN interfaces Ethernet vs. MPLS-TP in the Access Slide 28
  29. 29. CapEx:The Verdict Ethernet MPLS-TP Inexpensive, but can not scale Allows for significant cost Suitability forever reduction vs. full LSR 1 Point 2 Points R&D and volumes have driven MPLS-TP-specific devices Coverage down Ethernet CapEx can be low cost 4 Points 4 Points Many trials are using LSRs; MEF certification programs for chip sets are starting to Maturity carrier-grade Ethernet switches come out to address 4 Points 2 Points Total 9 Points 8 Points Ethernet vs. MPLS-TP in the Access Slide 29
  30. 30. OpEx:The Arguments• OpEx considerations that are taken into account: - Direct operations cost - Staffing - Minimizing “unchargeable” overhead• Reduction of direct operations costs for networks with large number of NEs : - Equipment must work reliably and be interoperate - Minimum touch (auto-discovery, zero-touch configuration., etc.) - Use of FM, Control Plane or Management Plane protocols• Maintaining competent staff requires: - Availability - Training - Employee retention• Overhead minimization applies to: - Per packet overhead - OAM, CP/MP packets Ethernet vs. MPLS-TP in the Access Slide 30
  31. 31. OpEx:The Arguments (Cont’) Ethernet • Basic Ethernet is zero-touch by design but carrier-grade may add many configuration parameters • A large number of useful L2CPs (STP, ELMI, GVRP) but no universal CP protocol • In addition to equipment certification, MEF has initiated certification for carrier Ethernet engineers • Main Ethernet overhead is large, but tags add only a small delta MPLS-TP • Basic MPLS relies on IP routing protocols but TP is designed to be able to function w/o CP • GMPLS CP has been defined as an option • Can operate without IP forwarding (eliminating IP logistics); CP and MP can be carried in GACh (although not yet developed) • Specific vendors have expert certifications but none specific to MPLS-TP • Same look and feel as other transport networks to minimize retraining • May leverage extensions to existing OSS Ethernet vs. MPLS-TP in the Access Slide 31
  32. 32. OpEx:The Verdict Ethernet MPLS-TP Metro Ethernets have been Designed to be Suitability shown to be low OpEx inexpensively maintainable 2 Points 2 Points Inelegant CP, available staff, Learned from previous Coverage medium overhead efforts 4 Points 4 Points Extensive operational Extensive experience and experience only partially Maturity certification programs applicable 4 Points 2 Points Total 10 Points 8 Points Ethernet vs. MPLS-TP in the Access Slide 32
  33. 33. Security:The ArgumentsThe Need: Security is perhaps the most important telecomm issue today• OAM, APS, QoS mechanisms are powerless to cope with Denial of Service attacks• Access network NEs are frequently physically unprotected, so: 1. Ports must be protected 2. Packets must be authenticated and integrity checked 3. Confidentiality mechanisms may be needed 4. MPs and CPs must be hard-state Ethernet vs. MPLS-TP in the Access Slide 33
  34. 34. Security:The Arguments (Cont’)Ethernet• Ethernet packets carry unique authenticatable source addresses• MACsec and its 802.1X extensions define mechanisms that can be used to protect carrier networks (although hop-by-hop security model may not always be ideal)MPLS-TP• MPLS was designed for core networks (walled gardens) with the assumption that there are no inside attacks• Forwarding plane attacks based on lack of authentication/integrity• Control plane attacks based on soft state of protocols Ethernet vs. MPLS-TP in the Access Slide 34
  35. 35. Security:The Verdict Ethernet MPLS-TP Has an authenticatable unique Has no source identifier and Suitability SA uses soft-state CPs 2 Points 0 Points MACsec and 802.1X, but may Little positive support (but it Coverage need more does support attacks …) 3 Points 1 Point MPLS community is not MACsec is starting to appear in addressing the TP security Maturity standard chipsets problem 2 Points 0 Points Total 7 Points 1 Points Ethernet vs. MPLS-TP in the Access Slide 35
  36. 36. Summary: Final Score Suitability Coverage Maturity Total Ethernet 16/20 35/40 38/40 89 MPLS-TP 14/20 27/40 11/40 52 Note: MPLS-TP lost • 29 points due to lack of maturity • 9 points due to lack of securityCaveats:• Deployments have particular (non)requirements, but all 10 considerations were given equal weight• Some coverage and all maturity scores will change over time Ethernet vs. MPLS-TP in the Access Slide 36
  37. 37. For information about RAD’sEthernet Access solutions,visit www.ethernetaccess.com www.rad.com Ethernet vs. MPLS-TP in the Access Slide 37

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