Metro ethernet metanoiainc-next-gen-workshop_2007-07-17

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Today’s emerging metro Ethernet networks represent a significant shift in the way in which data services are offered to enterprise and residential customers. With Ethernet emerging as the access interface of choice, services such as packet-leased line and virtual private LAN service are being delivered over a wide mix of transport technologies – SONET/SDH, next-gen SONET/SDH, Ethernet/WDM, and...

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  • Based on the MEF and IEEE classification, one can divide types of Ethernet service into the following 4 types. E-line- p2p connectivity – E.g. Used for Ethernet private line, Internet access, and p2p Ethernet VPNs. E-LAN- p2mp connectivity. E.g. Used for mp2mp Ethernet VPNs, Ethernet Transparent LAN service. Within E-line there is Ethernet Private Line – provided by a dedicated p2p circuit, with fixed, unshared bandwidth. Ethernet Virtual Private Line – provided by a multiplexed p2p circuit, with shared bandwidth. Ethernet Private LAN – provided by p2p circuits realizing mp2mp connectivity, with dedicated, unshared bandwidth. Makes a Metro-Ethernet Network appear like a LAN. Ethernet Virtual Private LAN – providing mp2mp connectivity over a shared infrastructure. Can be realized via shared, p2p circuits between endpoints.
  • Restriction on# of customers: carriers limited to 4096 customers. Even with Q-in-Q, the carrier is still restricted to 4096 global VLAN IDs within its network. While this number may be ok for experimentation, it is not appropriate for a large scale service! Service monitoring: There is not embedded service monitoring in Ethernet today. Thus, additional control plane intelligence is required to enable this. For instance, the Ethernet Virtual Connection service and associated parameters defined by MEF, require new protocols to meaningfully extract relevant performance parameters, and present it in a useful way. Today L2 backbones are limited by STP scalability. One problem with the STP is that it is designed fundamentally to prevent loops. Thus, it makes traffic flow depended on loop prevention rather than resource/bandwidth optimization. Carrying a VLAN through the network is not a simple task! A new VLAN today requires the careful configuration/coordination of VLAN IDs on all switches participating in the VLAN. There is no signaling protocol support to do so, thus task is manual, error-prone and tedious! Interworking with FR and ATM. How to connect new sites with Ethernet access with older sites/HQ enabled with FR/ATM. What if one end is bridged and the other is routed? RFC 2427 describes how to carry multi-protocol over FR, needs several inter-working functions, complicating things. By using a hybrid architecture, one may constrain the L2 Ethernet network to the access, where the inefficiencies of STP and VLAN limits are more controlled and limited. The core can be an IP/MPLS network. (In a L2 service, the carrier offers its customers the ability to transparently overlay their own networks on top of the carrier’s network.)
  • At its core an L2 VPN realized over an IP network can either provide a p2p service, as a replacement of traditional L2 VPN provided by FR and ATM, or a mp2mp service, as a replacement for a switched Ethernet service provided in traditional Ethernet networks. The provider core devices (VPLS devices) provide a logical interconnect such that the CE devices in a specific VPN appear to be on a single bridged Ethernet. As seen here, CE devices connect to PE routers via attachment circuits of various types. The PE routers in turn are connected by PWs running over tunnels, and form a virtual backbone that functions like a LAN. But what do the details of the PE1-PE2 connection look like? We see that next …
  • Here I’ve illustrated the key components of L2 VPNs, whether VPWS or VPLS. 1. The first are the AC’s that connect the CE switches/routers to the PE’s. These can be FR DLCI, ATM VCs, Ethernet port, Ethernet VLAN, PPP connection, PPP session in L2TP, MPLS LSP, and carries a frame from CE to PE. 2. The AC’s attach to a bridge module in the PE, which attaches via an emulated LAN interface to a forwarder. The forwarder modules are connected via PWs that travel over a PSN tunnel over a routed backbone. The bridge module functions as a std. Bridge, learning MAC addresses on the AC’s and possibly running SPT. 3. The Forwarder on receipt of a frame from an incoming AC over the emulated LAN interface, determines the outgoing PW, based on the incoming AC, the L2 header, and provisioned parameters. 4. The PWs are a pair of unidirectional VCs that originate/terminate at peer PE’s. They provide encapsulation of service-specific PDUs Help in managing the signaling, timing, and order of PDUs Coordinating/conveying service-specific status and alarms. 5. The PSN tunnel carries PW PDUs across the backbone, and can carry multiple PWs. Any tunneling technology with a demultiplexing field to identify the PW can be used. 6. Finally, there is PW signaling, which is essentially responsible for the exchange of the PW demultiplexer between PE’s, thus “setting up” the PW.
  • VPLS is an L2VPN that emulates a LAN, and provides full learning and switching capabilities. This is done by allowing PE routers to forward Ethernet frames based on the MAC addresses of the end stations that belong the the VPLS. There is full mesh of tunnels and PWs connecting the PE routers involved in a given VPLS, as shown here. Each VSI or forwarder maintains a table mapping MAC addresses to PWs. Performs MAC source address learning for frames received on the PWs. (The bridge module discussed earlier performs MAC address learning for frames received from AC’s.) It also does address aging, and split horizon for loop prevention. The bridge module attached to each VSI (not shown here), does MAC learning on ingress AC’s and may run SPT over the emulated LAN. The PE device is any edge router capable of running a signaling/routing protocol to setup PWs, and to setup transport tunnels to other PE’s to deliver PW traffic.
  • There are two sets of protocols to consider. Those in the control plane and those in the data plane. The control plane involves 2 control subflows: -- Exchange of PW labels across the backbone -- Establishment/assignment of tunnels for PW transport Explain the protocol combinations in the control plane that can be used – Targeted LDP and BGP. And LDP or RSVP-TE for tunnel setup. Talk a bit about the protocols and encapsulations in the data plane.
  • Learning and forwarding based on MAC address, and switching of packets between tunnels based on MAC addresses, plus interworking with IEEE 802.1 p/q tags and VLANS – achieved by the VSI forwarded and bridge modules per VPLS Support flooding of packets with unknown, broadcast,and multicast addresses, and replicate frames only to those VPLS devices that are part of the same VPN – via frame replication on PWs PE’s must be informed to auto-configure, and must learn of membership, tunneling etc. – via signaling protocols, targeted LDP or BGP. Membership discovery – via BGP or configuration Inter-provider connectivity should be possible: achieved by having a globally unique VPLS ID.
  • LDP signaling of VC labels for LSPs comprising the PW. Broadcast packet from a station arrives at PE1, the bridge module of PE1 associates Src= SA1 with the incoming/outgoing I/F 1 or port 1 or VLAN that the frame came on. PE1 recognizes (by configuration) that the frame belongs to VPLS A, and replicates it, transmitting along VC LSPs to PE2 and PE3. PE2 on receiving the frame on inbound VC LSP, associates that MAC with the remote end of the corresponding outbound VC LSP of the VC LSP pair that constitutes the PW between PE1 and PE2. Each PE signals different labels to its peers, so it can always distinguish between inbound frames from different PE’s.
  • The VLAN tag can be stripped, because it is assigned by the provider and known within the VPLS. As a result, it can be reapplied at the egress PE corresponding to a given VPLS.
  • This example shows how a full-mesh of PWs and tunnels, together with split-horizon forwarding provides loop freedom.
  • Simplifies signaling because amount of signaling goes down by as much as an order of magnitude! The full mesh between MTU routers, reduces to a mesh only between core PE’s and spoke VLLs. Reduces packet replication, since no replication is needed at MTU, except for local switching. The MTU cost comes down due to reduced computing requirements on it. Inter-domain connections can be realized via a single spoke, as opposed to a slew of VC LSPs. Addition of a new site only impacts the associated PE, and none of the other sites.
  • So, the number of LDP/BGP sessions to be supported comes down by two orders of magnitude. The number of MACs to be supported on a PE does increase by one order of magnitude, but that is still manageable. Later, we’ll see other architectural solutions to simplify this design, and divide the work between the core PE’s and the MTU PE’s appropriately.
  • Good afternoon! And welcome to the course on next-generation high-performance switch architectures. Thank you for coming. Over these two days my goal is to explore some details of this subject that will lead to a deeper understanding of the operation of canonical high-speed switch architectures. Before we begin, I’d like to give you a quick overview of the course, and of the sequence in which we’ll cover the material. The material is organized into 6 parts, half of which we’ll cover today. Today, we’ll begin with an overview of some basic switching notions and look at the essential architectural components of switches and cross-connects. We’ll also look at the generic data path processing that occurs within each. We will then look at a taxonomy of switch architectures and switching fabrics. Here we’ll cover the evolution of switch/routers over several generations, and examine the properties and features of different types of switching fabrics. We’ll also review the properties of input and output queueing. Having developed an overall understanding of the architectures of switches and routers, we’ll delve next into tracing the data path through an IP router, a TDM cross-connect, and a hybrid TDM/IP switch, and look at two examples in detail – the Cisco Catalyst switch and the Juniper M Series routers. Starting tomorrow, we will start dissecting each of the three main processing steps in a switch/router--- input processing, scheduling across the switch fabric, and output queuing. We’ll look at methods, algorithms, and techniques for each with a focus on hardware complexity and implementation issues. I have factored in time for discussions, so I hope you’ll ask questions freely at any time during these lectures. This will enable me to adjust my presentations to best help you. It will also make these lectures more interesting for me. If you have additional questions, please feel free to contact me after May 6 th . My contact information is on the title slide.
  • Path computation  To compute path while honoring constraints (E.g. CSPF) Need info. at source or central location Enhanced Routing  To distribute info. about network topology and link attributes Enhanced Signaling  Establish forwarding state Reserve resources along path Modify link attributes resulting from reservations Mechanism to support forwarding along path  Support for explicit routing, or MPLS as a forwarding mechanism
  • Since each remote CE must be able to pick a DLCI and a VPN label to communicate with the advertising CE. The VPN label needs to be separate for each remote CE because its traffic must uniquely map to a DLCI on the local PE-CE link.
  • Diffserv performs complex QoS functions such as classification, marking, metering, and shaping/policing at the edge, as far as possible, and performing queuing and scheduling in the network core. Traffic is classified and marked with the DSCP into a small number of traffic classes. In the core, scheduling/queuing is applied to the traffic classes based on the DSCP field; and any conditioning and dropping is also handled based on the DSCP. A traffic profile: specifies some properties of traffic that is to receive a certain level of service. The packet classifier helps to select flows that will receive a given service. It may be a simple one based on the DS byte or a complex multi-field classifier. The latter can distinguish between traffic from different flows arriving in the same interface but covered by separate SLAs. The meter monitors each substream identified by the classifier, typically via a logical token bucket/leaky bucket mechanism, configured with the parameters of the flow, and identifies packets as in-profile or out-of profile. The marker causes a packet to be treated per the SLA/TCA, by setting the value in the DS byte of the IP header, based on the classifier and metering function. This value determines the PHB to be received by packets within the domain. The shaper/dropper ensures that flows conform to the parameters of the particular traffic profile, and may cause some packets to be delayed/discarded to enable conformance with the profile. In the core, the packet is queued appropriately, and serviced by an appropriate scheduler. The PQ always serves the EF queue first, and seeks a packet from the WFQ scheduler when the EF queue is empty. The WFQ selects packets from the remaining queues, based on the weights allocated to them, and can follow a number of algorithms – CBQ, DRR, WRR, etc.
  • -- Packets belonging to different PHBs but belonging to the same PHB scheduling class should not be misordered -- Packets of a common PHB scheduling class must travel on the same LSP -- How to determine different PHBs of a PHB scheduling classs? -- Take the help of EXP bit One observation if the network supports fewer than 8 PHB then we can use EXP bits An LSP set up under these conditions is called E-LSP What if we need more than 8 PHB? We need to provide information inside labels This requires enhancing Label Distribution Protocol also Label can now be bound to both <FEC, PHB>
  • One observation if the network supports fewer than 8 PHB then we can use EXP bits An LSP set up under these conditions is called E-LSP What if we need more than 8 PHB? We need to provide information inside labels This requires enhancing Label Distribution Protocol also Label can now be bound to both <FEC, PHB> -- Packets belonging to different PHBs but belonging to the same PHB scheduling class should not be misordered -- Packets of a common PHB scheduling class must travel on the same LSP -- How to determine different PHBs of a PHB scheduling class? -- Take the help of EXP bit
  • Good afternoon! And welcome to the course on next-generation high-performance switch architectures. Thank you for coming. Over these two days my goal is to explore some details of this subject that will lead to a deeper understanding of the operation of canonical high-speed switch architectures. Before we begin, I’d like to give you a quick overview of the course, and of the sequence in which we’ll cover the material. The material is organized into 6 parts, half of which we’ll cover today. Today, we’ll begin with an overview of some basic switching notions and look at the essential architectural components of switches and cross-connects. We’ll also look at the generic data path processing that occurs within each. We will then look at a taxonomy of switch architectures and switching fabrics. Here we’ll cover the evolution of switch/routers over several generations, and examine the properties and features of different types of switching fabrics. We’ll also review the properties of input and output queueing. Having developed an overall understanding of the architectures of switches and routers, we’ll delve next into tracing the data path through an IP router, a TDM cross-connect, and a hybrid TDM/IP switch, and look at two examples in detail – the Cisco Catalyst switch and the Juniper M Series routers. Starting tomorrow, we will start dissecting each of the three main processing steps in a switch/router--- input processing, scheduling across the switch fabric, and output queueing. We’ll look at methods, algorithms, and techniques for each with a focus on hardware complexity and implementation issues. I have factored in time for discussions, so I hope you’ll ask questions freely at any time during these lectures. This will enable me to adjust my presentations to best help you. It will also make these lectures more interesting for me. If you have additional questions, please feel free to contact me after May 6 th . My contact information is on the title slide.
  • LDP Due to a direct label exchange between peers, PE can send a separate label to each peer (which is what is desired). It is possible to physically segment the network into PE’s that have separate VPLS coverage, so those PE’s that have no VPLS in common do not form any adjacencies. This reduces signaling and # FIBs/PE. BGP The segmentation of PE’s into the VPLS’s they serve is the result of filtering based on the RT attribute, but all of the information does go to every PE.
  • BGP NLRI either represents a VPLS or represents a CE that is an L2 VPN endpoint.
  • Since each remote CE must be able to pick a DLCI and a VPN label to communicate with the advertising CE. The VPN label needs to be separate for each remote CE because its traffic must uniquely map to a DLCI on the local PE-CE link.
  • Now each remote PE must be able to pick a VC LSP label to communicate with the advertising PE. Separate label is needed because you want to know the PE behind which a MAC address lies.
  • Metro ethernet metanoiainc-next-gen-workshop_2007-07-17

    1. 1. Metanoia, Inc.Critical Systems Thinking™ Metro Ethernet:Understanding Key Underlying Technologies Metanoia, Inc. consultants@metanoia-inc.com +1-888-641-0082 http://www.metanoia-inc.com © Copyright 2007 All Rights Reserved
    2. 2. Metanoia, Inc. Critical Systems Thinking™Who is Metanoia, Inc.? Specialty technology consultancy founded in mid-2001, with HQ in Mountain View, California Undertakes deep-dive technical consulting in telecom network, systems, software and chip architecture and design for clients across the world Services have spanned 4 continents, with clients in: North America, Europe, Asia, and Australia. Principals provided services in technology strategies, architecture and design trade-offs, product development, hardware/software architecture, and knowledge enhancement to organizations that include large equipment manufacturers, international, national and regional ISPs, premier metro/access systems startups, network planning tool vendors, established software and technology houses and leading component and semiconductor vendors Principals are technologists at the forefront of new developments, as leaders, creators, implementers, researchers, academics, strategists, and advisors in the US and abroad Expertise spans Layer 1 through Layer 4, and wireline (optical, Ethernet, IP/ATM, SONET/SDH) through wireless (Wi-Fi, cross-layer design, Wi-Max, cellular data, 2.5-3G) 125+ man years of technology design and development, and technology management experience, having worked at leading global corporations, such as Apple, AOL Time Warner, BBN, Cisco, 3Com, Fujitsu, LSI Logic, Motorola, Tellabs, Siemens, Nokia, Tibco, and Qualcomm, and having worked at/consulted to corporates in the US and abroad for almost the last decade 70+ patents collectively issued/pending Advanced graduate degrees from some of the most distinguished universities in the world – the University of California, Stanford University, Iowa State University, the University of Texas, the University of Waterloo, and the Indian Institute of Technology Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 2
    3. 3. Metanoia, Inc. Critical Systems Thinking™Workshop Outline Legacy networks & Ethernet over legacy networks  Value propositions and business drivers  Ethernet over SDH/SONET Metro Ethernet Forum (MEF)  MEF architecture  E-Line and E-LAN services Native Ethernet as Carrier-class transport  Provider Bridges  Provider Backbone Bridges (PBB), Provider Backbone Transport (PBT) MPLS – an enabler for Ethernet services Layer 2 VPNs: VPWS, VPLS, H-VPLS Advanced concepts: traffic engineering, QoS, OAM, resilience Conclusions Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 3
    4. 4. Metanoia, Inc.Critical Systems Thinking™ Ethernet over Legacy Networks
    5. 5. Metanoia, Inc. Critical Systems Thinking™Issues with Legacy Networks Low bandwidth No flexibility to scale High cost of installation Slow provisioning Bandwidth growth inflexible/non-linear  Limited by multiplexing hierarchy TDM-based access: inefficient for converged data Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 5
    6. 6. Metanoia, Inc. Critical Systems Thinking™Next-Generation SDH Customer Network Central NG-SDH Office NG ADM Switch t Ck M TD Ethernet Core NG-SDHNetwork Customer NG ADM Network STM/4/16 Cross TD M Ring Connect Ck t NG NG-SDH ADM Customer Ethernet Network Customer Network Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 6
    7. 7. Metanoia, Inc. Critical Systems Thinking™Ethernet-over-SDH Framing protocol  Encapsulates Ethernet frames in SDH payloads Mapping of SDH payload to SDH channels  Virtual concat.: for allocation of non-contiguous VCs Flow control mechanism  Avoids packet drops due to speed mismatch between SDH and Ethernet Mechanism to increase/decrease allocated SDH bandwidth  Add or remove VCs Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 7
    8. 8. Metanoia, Inc. Critical Systems Thinking™Ethernet-over-SDH (contd) Very popular in carriers with installed base of SDH rings  E.g. BSNL in India Good deployment choice when traffic primarily circuit switched Inefficient if major traffic is bursty packet-switched data  Solution: Carrier-class Ethernet! Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 8
    9. 9. Metanoia, Inc. Critical Systems Thinking™Metro Ethernet Value Propositions Lower per-user provisioning costs  Technically simple relative to TDM ckts.  Due to large installed base Efficient and flexible transport  Wide range of speeds: 128 Kbps--10 Gbps  QoS capabilities Ease of inter-working  Plug-and-play feature Ubiquitous adoption  The technology of choice in enterprise networks Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 9
    10. 10. Metanoia, Inc. Critical Systems Thinking™Ethernet Business Drivers Business connectivity  Storage networks  Data centers  Video conferencing Residential services  Triple-play services (IPTV)  On-line gaming  High-speed Internet access Wireless backhaul  Reduced cost, complexity for mobile operators Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 10
    11. 11. Metanoia, Inc.Critical Systems Thinking™ Metro Ethernet Services
    12. 12. Metanoia, Inc. Critical Systems Thinking™Metro Ethernet Forum (MEF) Industry forum at forefront of Carrier Ethernet standardization  Carrier Ethernet architecture  Ethernet services  Founded in 2001. Currently approx. 120 members Technical Sub-committees  Architecture  Services  Protocols and Transport  Management Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 12
    13. 13. Metanoia, Inc. Critical Systems Thinking™MEN Architectural Components T T S S End Customer Customer End Network MEN Network User User End user Interface End user Interface UNI Reference Point UNI Reference Point Ethernet Virtual Connection End-to-End Ethernet Flow Ethernet Flow  Unidirectional stream of Ethernet frames UNI  Interface used to interconnect MEN subscriber to provider EVC  Defines association between UNI for delivering Ethernet flow across MEN Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 13
    14. 14. Metanoia, Inc. Critical Systems Thinking™MEN Layer Model Application Service Layer (IP, MPLS, PDH, E1/E3, SDH) Ethernet Service Layer Transport Service Layer (802.1, SONET/SDH, MPLS) MEN Layer Model Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 14
    15. 15. Metanoia, Inc. Critical Systems Thinking™MEF Services Definition Framework Service Type  Construct used to create broad range of services Service Attributes  Defines characteristics of a service type Attribute Parameters  Set of parameters with various options Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 15
    16. 16. Metanoia, Inc. Critical Systems Thinking™Service Types E-Line EVC1  Point-to-point Ethernet Virtual Circuit (EVC) EVC2 E-LAN  Multipoint-to-multipoint Ethernet Virtual Circuit Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 16
    17. 17. Metanoia, Inc. Critical Systems Thinking™Service Attributes Physical Interface  Medium, speed, mode, MAC layer Traffic Parameters  CIR, CBS, PIR, MBS QoS Parameters  Availability, delay, jitter, loss Service Multiplexing  Multiple instances of EVCs on a given physical I/F Bundling  Multiple VLAN IDs (VID) mapped to single EVC at UNI Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 17
    18. 18. Metanoia, Inc. Critical Systems Thinking™Ethernet Services Ethernet Private Line (EPL)  Uses E-Line  Does not allow service multiplexing  High degree of transparency  Low delay, delay variation, and packet loss ratio Ethernet Virtual Private Line (EVPL)  Uses E-Line  Allows for service multiplexing  Need not provide full transparency Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 18
    19. 19. Metanoia, Inc. Critical Systems Thinking™Service Types and Ethernet Services Service Types E-Line E-LAN (p2p connectivity) (mp2mp connectivity) Ethernet Private Ethernet Virtual Ethernet Private Ethernet Virtual Private Line (E-line) Private Line (E-VPL) LAN (E-LAN) LAN (E-VPLAN) Ethernet Services Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 19
    20. 20. Metanoia, Inc.Critical Systems Thinking™ Native Ethernet as Carrier-class Transport
    21. 21. Metanoia, Inc. Critical Systems Thinking™Requirements for Carrier-class Ethernet Scalability  Network should support millions of subscribers Protection and restoration  50ms resilience Quality-of-Service (QoS)  Ability to offer differentiated levels of service Service Monitoring and Fault Management Support for TDM traffic  Seamless integration with legacy networks Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 21
    22. 22. Metanoia, Inc. Critical Systems Thinking™Ethernet Ring Ethernet Switch Ethernet Ethernet Switch Switch Core 1/10 Gigabit Ethernet Customer Network Ethernet Ring Network Ethernet Switch Ethernet Customer Network Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 22
    23. 23. Metanoia, Inc. Critical Systems Thinking™Native Ethernet in Metro Access How does one create the notion of a virtual circuit?  VLAN tagging with point-to-point VLAN VLAN stacking  Outer tag ↔ service instance; Inner tag ↔ individual customer  802.1Q in 802.1Q (Q-in-Q) - IEEE 802.1ad 6bytes 6bytes 4bytes 4bytes 4bytes C-DA C-SA S-TAG C-TAG Client data FCS C-DA: Customer Destination MAC C-SA: Customer Source MAC C-TAG: IEEE 802.1q VLAN Tag C-FCS: Customer FCS S-TAG: IEEE 802.1ad S-VLAN Tag Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 23
    24. 24. Metanoia, Inc.Provider Bridge (IEEE 802.1ad) Critical Systems Thinking™Architecture CE-B CES Customer CE-A UNI-B NetworkCustomer Network CES UNI-A CES Spanning tree UNI-C CE-CCE: Customer EquipmentUNI: User-to-Network Interface CustomerCES: Core Ethernet Switch/Bridge NetworkP-VLAN: Provider VLAN Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 24
    25. 25. Metanoia, Inc. Critical Systems Thinking™Limitations of Provider Bridge Scalability Limited to 4096 service instances Core switches must all MAC addresses Broadcast storms ensue due to learning MAC address tables explode! Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 25
    26. 26. Metanoia, Inc. Critical Systems Thinking™Provider Backbone Bridging (802.1ah) Encapsulate customer MAC with provider MAC at edge  Edge switch adds 24-bit service tag (I-SID), not VLAN tag Core switches need only learn edge switch MAC adds. 6bytes 6bytes 4bytes 5bytes 6bytes 6bytes 4bytes 4bytes B-DA B-SA B-TAG I-TAG C-DA C-SA C-TAG Client data B-FCS S-TAG: IEEE 802.1ad S-VLAN Tag B-DA: IEEE 802.1ah Backbone Destination B-SA: IEEE 802.1ah Backbone Source MAC I-TAG: IEEE 802.1ah Service Tag Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 26
    27. 27. Metanoia, Inc. Provider Backbone Bridging (PBB) Critical Systems Thinking™ Architecture CPE B CPE A CPE B CPE A CPE C CPE D Provider backbone Provider backbone network (802.1ad) 802.1ad network (802.1ad) Provider backbone network (802.1ah) Provider backbone network (802.1ad) Provider backbone network (802.1ad) 802.1qCPE C CPE B CPE B CPE A CPE D CPE C Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 27
    28. 28. Metanoia, Inc. Critical Systems Thinking™Benefits of PBB Scalability  Addresses limitations of 4096 service instances Robustness  Isolates provider network from broadcast storms Security  Provider need switch frames only on provider addresses Simplicity  Provider & customers can plan networks independently Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 28
    29. 29. Metanoia, Inc. Critical Systems Thinking™Traffic Engineering in PBB Via Multiple Spanning Tree Protocol (MSTP) Maps a VLAN to ST or multiple VLANs to ST Enables use of links that would otherwise be idle in ST  Eliminates wasted bandwidth … but … Too slow for protection switching Not suitable for complex mesh topologies Difficult to predict QoS Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 29
    30. 30. Metanoia, Inc.Challenges with an All-Ethernet Critical Systems Thinking™Metro Service Restriction on # of customers – 4096 VLANs! Service monitoring Scaling of Layer 2 backbone Service provisioning  Carrying a VLAN is not a simple task! Inter-working with legacy deployments ⇒ Need hybrid architectures … Multiple L2 domains connected via IP/MPLS backbone Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 30
    31. 31. Metanoia, Inc. Critical Systems Thinking™What Solutions do we Have? Ethernet-based Architecture  Provider Bridge (802.1ad) in edge  Provider Backbone Transport (PBT) in Core Hybrid Architecture  802.1ad in the edge  Multiprotocol Label Switching (MPLS) in core Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 31
    32. 32. Metanoia, Inc. Critical Systems Thinking™Provider Backbone Transport (PBT) Connection-oriented, traffic-engineered Ethernet tunnels Replaces spanning tree control plane with either a:  Management plane  External control plane No learning !  Forwarding info. provided by management plane Forwarding done on MAC + VID (60-bit) address  VID is not network global; however, MAC + VID is  B-MAC identifies destination  B-VID identifies per-destination alternate paths Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 32
    33. 33. Metanoia, Inc. Critical Systems Thinking™PBT Architecture Central TE Module PE2 PE1 CustomerCustomer Network Network SA : PE1 SA : PE1 DA : PE2 DA : PE2 VLAN 22 VLAN 33 Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 33
    34. 34. Metanoia, Inc. Critical Systems Thinking™Benefits of PBT No learning  Eliminates undesirable broadcast storms  Resolves MAC flooding problem  Addresses scaling by forwarding on MAC + VID-highly scalable Protection  Sets-up backup paths  50ms restoration possible QoS support available Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 34
    35. 35. Metanoia, Inc.Critical Systems Thinking™ MPLS – An Enabler for Ethernet Services: Fundamentals & Operations
    36. 36. Metanoia, Inc. Critical Systems Thinking™ Basic Concept of MPLSDA Next hop N/w DA Next hop N/w router Int. router Int.129.89.10.x 198.168.7.6 1 129.89.10.x 129.89.10.1 1 Routing Table179.69.x.x 198.168.7.6 1 179.69.x.x 179.69.42.3 2 128.89.10.xIn Out Address Prefix N/w In Out Address Prefix N/w label label 128.89.10.1label Int. label Int. X 3 1 3 5 1 Label Table 2 128.89.10.x 128.89.10.x X 4 179.69.x.x 1 4 7 179.69.x.x 2 R3 Advertises binding 1 <5, 128.89.10.x> R1 1 R2 2 198.168.7.6 Advertises bindings Advertises binding <3, 128.89.10.x> <7, 179.69.x.x> <4, 179.69.x.x> 179.69.x.x  Routing fills routing table R4  Signaling fills label forwarding table 179.69.42.3 Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 36
    37. 37. Metanoia, Inc. Critical Systems Thinking™ Basic Concept of MPLS Pop label 5 In Out Address Prefix N/w In Out Address Prefix N/w Forward label label Int. label label Int. packet X 3 1 3 5 5 128.89.10.x 1 5 128.89.10.x 3 128.89.10.x X 4 179.69.x.x 1 4 7 179.69.x.x 2 128.89.10.1 2 R3 Swap Label 5 3 1 R1 1 R2 2 3 198.168.7.6 Push LabelPacket arrivesDA=128.89.10.25 179.69.x.x R3 R4 179.69.42.3 Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 37
    38. 38. Metanoia, Inc. So what about MPLS Control and Critical Systems Thinking™ Forwarding?  Superset of conventional router controlControl  Distribute info. via n/w layer routing protocols (OSPF, BGP, etc.)Component  Algos. to convert routing info. into forwarding table: Create binding from FEC  label Assign & distribute labels to peer LSRs via signaling  Label switching forwarding table (or label information base LIB) Incoming Label First Subentry Second Subentry Map (for multicast or load balancing) Outgoing label Outgoing label Incoming Outgoing inf. Outgoing inf. Label Next hop address Next hop addressForwardingComponent Next hop label forwarding entry (NHFLE)  Forwarding algo = label swapping, independent of control component (implementable in optimized H/W or S/W) Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 38
    39. 39. Metanoia, Inc.What does a Label Represent? The Critical Systems Thinking™Issue of Label Granularity Packets form Forwarding Equivalence Class (FEC)  Treated identically by participating routers  Assigned the same label Membership in FEC must be determinable from IP header + other info. that ingress router has about the packet Entities that may be grouped into an FEC are flexible. E.g. FEC could be:  Connection between two IP ports on two hosts or between IP hosts  Traffic headed for a particular network with same TOS bits  All destination networks with a certain prefix  Manually configured connection  Traffic belonging to a customer or department VLAN  Traffic of a given application – voice, video, plain data, management traffic … and many others Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 39
    40. 40. Metanoia, Inc. Critical Systems Thinking™Let’s Recap: Elements of MPLS  Label Forwarding  Use data link addressing. E.g. ATM VPI/VCI, FR DLCI  “Shim” header between data link and IP header Data Plane Variable 4 bytes 20 bytes MPLS “shim” Higher Layers L2 header header L3 IP header 1 bit EXP/ Label S TTL CoS 20 bits 3 bits 8 bits  Label Creation and BindingControl Plane  Label Assignment and Distribution  Ride piggyback on routing protocols, where possible (BGP)  Separate label distribution protocol – RSVP, LDP Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 40
    41. 41. Metanoia, Inc.Primary Label Assignment and Critical Systems Thinking™Distribution Modes 1 Requests Edge LSR 2 6 5 3 4 Downstream-on-demand with Ordered Control Assignments Edge LSR 1 Requests Edge LSR 2 Assignments 2’ 3’ 3 4 Downstream-on-demand with Independent Control Edge LSR Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 41
    42. 42. Metanoia, Inc. Critical Systems Thinking™ Advantages of MPLS Original justification  Availability of fast, amortized, ATM hardware; emergence of H/W forwarding engines has practically eliminated this Current justifications  Separates forwarding from control, allowing  Routing functionality to evolve independently of forwarding algorithm  MPLS to control non-packet technologies: SONET/SDH ckts., lightpaths  Provides explicit, manageable IP routes  Enables policy routing and traffic engineering  Offers TE for Ethernet tunnels in metro-Ethernet environments  Facilitates scalable hierarchical routing Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 42
    43. 43. Metanoia, Inc. Critical Systems Thinking™The Utility of Hierarchical Label Switching Edge LSRs SwapSwap Core LSRsand Push Pop Concept is similar to VLAN stacking in PBT we saw earlier Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 43
    44. 44. Metanoia, Inc. Critical Systems Thinking™ Hierarchical Label Stacking/Switching  Inside a transit AS, each core router must keep track of all networks that might be reached through it  With hierarchical labels, only edge routers need know what networks might eventually be reached through them  All transit traffic can be made to tunnel through core routers using LSPs with stacked labels Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 44
    45. 45. Metanoia, Inc.Explicit Manageable Routes -- Policy Critical Systems Thinking™routing, Traffic engineering  Carriers want certain traffic to go over certain routes. Such network engineering:  Keeps network loads balanced  Enhances network stability and reliability  Enables better QoS and performance assurances  Allows carriers to meet customer SLAs  Constraint-based routing together with MPLS allows carriers to  Bind Ethernet tunnels to an LSP,  Place (or route) LSP over the desired sequence of LSRs in the n/w  TE tunnels are helpful for VPLS-based carrier Ethernet n/ws Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 45
    46. 46. Metanoia, Inc.Critical Systems Thinking™ IP/MPLS-based Layer 2 VPNs
    47. 47. Metanoia, Inc. Critical Systems Thinking™L2 VPN Components VC LSP A A Emulated PE1 LAN A PE2 B Routed B backbone AC Emulated LAN B PE3 What does the P1-PE2 connection really look like? Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 47
    48. 48. Metanoia, Inc. Critical Systems Thinking™ L2 VPN Component Details 6 PW Signaling PE1 PE2 From CE devices 5 PSN Tunnel 3 PWs Routed backbone1 ACs 2 From CE with P routers Bridge devices Module Emulated LAN 4 Forwarder Instance Emulated LAN Interface Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 48
    49. 49. Metanoia, Inc. Critical Systems Thinking™VPLS Network Overview PW A LAN Service (full mesh) VSI VSI VSI CE L3/MPLS VSI Backbone B B CE AC A VSI Tunnel LAN Service (full mesh) Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 49
    50. 50. Metanoia, Inc. Critical Systems Thinking™ VPLS Protocols InvolvedControl Ethernet MP-iBGP (PW) + RSVP-TE /LDP (tunnel) Ethernet Plane STP Targeted LDP (PW) + LDP (tunnel) STP A BGP/Targeted LDP PE PE CE LSP or PSN Tunnel B B CE Ethernet Ethernet/MPLS Ethernet Data Ethernet or Ethernet or Ethernet/IPSec Plane Ethernet in IP/ Ethernet/GRE Ethernet in IP/ ATM/FR/SDH/ ATM/FR/SDH/ SONET SONET Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 50
    51. 51. Metanoia, Inc. Critical Systems Thinking™Operational Characteristics of VPLS Operational Requirement Realized Via MAC address learning and - VSI Forwarder switching, work with 802.1p/q - Bridge Module tags and VLANs Flooding pkts. with unknowns Frame replication on PWs broadcast, or multicast address Provider edge signaling – inform - Targeted LDP PEs to autoconfigure, and of - BGP membership, tunnelling - BGP VPLS membership discovery - Configuration Inter-provider connectivity Globally unique VPLS ID Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 51
    52. 52. Metanoia, Inc.Data Plane: Flooding, Address Critical Systems Thinking™Learning and Forwarding Src. MAC = 09:10:01:45:00:AB 1 Dest. MAC = 08:00:69:02:01:FC 3 A VSI 2 VSI CE ? VSI PWs PE2 PE1 B 2 PE3 PE4 B A VSI VSI CE 3  All address unknown frames (unicast, multicast, broadcast) flooded over corresponding PWs to all relevant PEs only Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 52
    53. 53. Metanoia, Inc. Critical Systems Thinking™Address Learning Layer 2 reachability directly learned in data plane Use standard learning bridge functions for local MACs PW-based association for remote MACs  Allow PE to determine from which physical port or LSP a given MAC address came VSI FIB keeps mapping between Ethernet MAC ↔ PW to use Qualified Learning Unqualified Learning- Each customer VLAN is its own - All customer VLANs are part of VPLS instance the same VPLS- Has its own PW mesh and brdcast - One PW mesh and single brdcast domain domain Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 53
    54. 54. Metanoia, Inc. Critical Systems Thinking™Address Learning Example Src. MAC = 08:AA:FC:01:10:DE (S1) 2 Dest. MAC = FF:FF:FF:FF:FF:FF (D1) (broadcast) 4 1 VSI A Inbound CE VC LSP Label = 1002 i/f1 i/f2 i/f1 VSI PE1 PE2 3 Outbound Local Learning VC LSP Label = 2001 Dest. VC Tunnel Out I/F MAC Label S1 1002 - i/f1 PE3 Remote Learning Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 54
    55. 55. Metanoia, Inc. Critical Systems Thinking™Forwarding and EncapsulationForwarding requires ability to Dynamically learn MAC addresses on  Physical ports  Pseudowire VCs (VC LSPs) Forward/replicate pkts. across physical ports and VC LSPsEncapsulation PW header applied to Ethernet packet w/o preamble + FCS VLAN tag denoting customer’s VPLS instance can be stripped at ingress, reapplied at egress Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 55
    56. 56. Metanoia, Inc.Tunnel and PW Topology and Critical Systems Thinking™Loop Freedom Dest. MAC = 08:00:69:02:01:FC PW A ? (full mesh) VSI VSI PE1 PE2 VSI CE VSI B AC CE A Tunnel (full mesh) VSI PE3 PE4 Full mesh of PW and tunnels deployed Tunnels  Help transport the PW payload  Aggregate traffic from multiple PWs Pseudowires – demultiplex the L2 traffic traversing tunnels Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 56
    57. 57. Metanoia, Inc. Critical Systems Thinking™Scaling VPLS: Hierarchical VPLS Base VPLS requires full mesh of VC LSPs between PE routers Adequate for PE routers in CO – multiple customers aggregated Inadequate for PE routers in MTU basements! MTU MTU PE PE MTU MTU PE PE LSP explosion Operational nightmare! PE MTU Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 57
    58. 58. Metanoia, Inc. Critical Systems Thinking™Hierarchical VPLS Advantages MTU MTU PE PE Hub PE MTU Core VC MTU LSP mesh PE Spoke PE VCs (VLL or Q-in-Q) Benefits  Simplifies signaling  Reduces pkt. replication PE MTU  Simplifies MTU  Scalable inter-domain VPLS  Simplifies new site addition Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 58
    59. 59. Metanoia, Inc. Hierarchical VPLS: Case Study for Critical Systems Thinking™ a Metro Region 100 MTUs; 10 customers/MTU; 2 VPLS/cust.; 100 stations/VPLS VPLSs/MTU = 10x2 = 20 MTU100 MTU91 MACs/MTU = 20x100 = 2000 CE CE MTU1 MTU 100 PE PE MTU1 Hub PE MTU90 CE CEMTU2 MTU99 MTU10 PE PE MTU81 PE PE CE CE PE PE PE CE CE MTU3 MTU40 MTU31 MTU40 No hierarchy ⇒ PE supports Hierarchy (10 MTU/PE) ⇒ PE 2000 MACs supports LDP/BGP sessions = (100x99)/2 x 2000 x 10 = 20,000 MACs 20 = 245,000 LDP/BGP sessions = (10x9)/2 x 200 = 9000 Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved # of spoke VLLs = 10 x 20 = 200 2007, Bangalore, India 59
    60. 60. Metanoia, Inc. Critical Systems Thinking™Benefits of IP/MPLS-based L2 VPNs Separation of administrative responsibilities Migration from traditional L2 VPNs: seamless transport of Ethernet services Privacy of routing Layer 3 independence Less operational overhead Ease of configuration (?) Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 60
    61. 61. Metanoia, Inc.Critical Systems Thinking™ Advanced Features: Traffic Engineering, Resilience, OAM, QoS
    62. 62. Metanoia, Inc.Critical Systems Thinking™ Traffic Engineering Concepts © Copyright 2006 All Rights Reserved
    63. 63. Metanoia, Inc. Critical Systems Thinking™Constraint Based Routing  A class of routing systems that computes routes through a network subject to a set of constraints and requirements QoS-based Routing Policy-based Routing  Path of flows determined by  Path/routing decision based  Knowledge of resource on administrative policy availability in network  QoS requirements of flows  Can be on-line or off-line Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 63
    64. 64. Metanoia, Inc. Critical Systems Thinking™CB Routing System  Inputs Resources  Flow/path attributes: required b/w, hop count, ...  Resource attributes: Attributes Topology properties of nodes/links  Network topology & state Constraint-Based Routing Process  Outputs  Computed feasible path Feasible Path ERO {1,3,4,5}  Explicit route of the path 3 5 1 4 2 Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 64
    65. 65. Metanoia, Inc.Critical Systems Thinking™ MPLS-based Resilience for the Metro © Copyright 2006 All Rights Reserved
    66. 66. Metanoia, Inc. Critical Systems Thinking™Fundamental Characteristics of RSVP  Allows apps. to signal QoS requests to n/w, and n/w to respond with success or failure  Designed to transport  Classification info. (Sender_Template)  Allows flows with specific QoS reqs. to be recognized  Traffic specs of source/sender (Tspec)  QoS needs of receivers (Rspec)  Soft-state protocol  Path/Resv transmitted periodically to refresh reservation  Refresh Reduction [RFC2961] has practically eliminated original scalability concerns with use of soft state Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 66
    67. 67. Metanoia, Inc. Critical Systems Thinking™ Basic Operation of RSVP-TE Path (Label_Req) Path (Label_Req) A B C D E Resv Resv Resv Resv Label=21 Label=49 Label=7 Label=5Path Message Resv Message RSVP Header RSVP Header Application for which RSVP SESSION Same as that in Path Msg. reservation is to be made SESSION Identifies pkts. of the sender Specifies senders that maySENDER_TEMPLATE STYLE use the reserved resources SENDER_TSPEC Defines traffic output by sender LABEL Label assigned to this hop LABEL_REQUEST Request for label on this hop RRO Record route taken by Path Specific path to which flow is ERO/RRO RSpec QoS desired by receiver to be boundSESSION_ATTRIBUTE Flow for which QoS is LSP attributes for this sender SENDER_TEMPLATE desired PHOP IP address of I/F that NHOP IP address of I/F originating transmitted Path Msg. the Resv msg. Flow Descriptor Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 67
    68. 68. Metanoia, Inc. Fast Re-Route (FRR) using Critical Systems Thinking™ RSVP-TE Rerouting is done when  A better path is available Originates LSPs with IDs 1 and 2  Upon failure along LSP Src Here they are treated as different LSPs within the same Session Use SESSION Obj. & SE style Rcvr Tunnel ID in LSP ID = L1 Session Obj Tunnel uniquely identified by  Destination IP address  Tunnel ID  Ingress IP address Tunnel ingress made to appear LSP ID = L2 On these links the as 2 different senders to the LSPs share resources RSVP session (via LSP ID) LSPs 1 and 2 have a common SESSION Obj, but a new LSP ID in the SENDER_TEMPLATE and a different ERO (with possibly common hops) Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 68
    69. 69. Metanoia, Inc. TE with Constraint-based Routing Critical Systems Thinking™ in a Nutshell Operator Input Route Computation Resource Enhanced IGP (Flow or LSP Process TED Attributes Process Attributes) (on-line (CSPF) or offline) (OSPF-TE) Network Output Topology + State Routing Table Computed (RIB)Demand or Traffic driven feasible path (ERO) Control driven route computation LSP path selection and LSP path selection Link State Signaling Process Database Standard IGP (RSVP-TE) (LSDB) Process (OSPF) CONTROL PLANE DATA PLANE LSP Establishment Link Attribute Modification MPLS LSPs (Label Info. Base) Forwarding Info. Base (FIB) Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007 All Rights Reserved 2007, Bangalore, India 69
    70. 70. Metanoia, Inc. Critical Systems Thinking™How it All Fits Together Last-mile Ethernet PBB clouds CE3 LSP Tunnels CE1 PE1 PE3 CE4 Pseudo-wires PE2 IP/MPLS Core CE2 Attachment circuits -- Physical (PDH/SDN) -- Logical (FR, ATM, VLANs, tunnels) Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 70
    71. 71. Metanoia, Inc.Critical Systems Thinking™ OAM: The Traditional Achilles Heel of Ethernet © Copyright 2006 All Rights Reserved
    72. 72. Metanoia, Inc. Critical Systems Thinking™Why Ethernet OAM? Current management protocols lack per-customer granularity to handle Ethernet services Most management protocols operate are point-to-point  Ethernet OAM can exploit multipoint capability Link management required for last-mile connection  Similar to link mgt. in FR and ATM Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 72
    73. 73. Metanoia, Inc. Critical Systems Thinking™Ethernet OAM Types Service OAM  e2e connectivity and fault mgt. per service instance  Part of IEEE 802.1ag, CFM project Link OAM  Monitoring & fault mgt of individual Ethernet link (physical/emulated)  Part of IEEE 802.3, Clause 57 (formerly 802.3ah (not to be confused with 802.1ah)) Ethernet Local Mgt. Interface (E-LMI)  Configuration & operational provisioning of customer edge device  Part of MEF Standard MEF-16 Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 73
    74. 74. Metanoia, Inc. Critical Systems Thinking™Service OAM Works on per-EVC basis  Independent of underlying transport technology CFM messages  Continuity Check Message  Detects loss of service connectivity  Link Trace Message  Traces the path hop-by-hop (like IP traceroute)  Loopback Message  Detects whether target point is reachable (like ICMP Ping)  AIS (Alarm Indication Signal) Message  Asynchronous notification to indicate fault Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 74
    75. 75. Metanoia, Inc. Critical Systems Thinking™Link OAM Discovery  Identifies devices at both ends of the link Link Monitoring  Detects link faults  Statistics of packet errors Remote Failure Indication  Conveys loss-of-signal indication to peers, due to poor SNR, power failure, or other critical events Remote Loopback  Determines quality of link during installation and troubleshooting Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 75
    76. 76. Metanoia, Inc. Critical Systems Thinking™E-LMI Provides local configuration & operational parameters to customer edge  VLAN-EVC mapping  QoS profiles of EVC Reduces configuration errors, improves performance  Dynamic EVC management Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 76
    77. 77. Metanoia, Inc.Critical Systems Thinking™Quality-of-Service: Ah! that elusive QoS © Copyright 2006 All Rights Reserved
    78. 78. Metanoia, Inc.MPLS and Quality-of-Service for Critical Systems Thinking™Ethernet Services MPLS supports (not extends) a packet-based QoS model MPLS does not run in hosts (only in metro/core routers)  QoS, however, is an end-to-end mechanism MPLS helps carriers offer QoS-enabled services efficiently  Can support MEF QoS model via DiffServ QoS framework Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 78
    79. 79. Metanoia, Inc. Critical Systems Thinking™Differentiated Services Framework Traffic flows aggregated into small # of classes Drop Precedence Class Priority DSCP EF 101110 Per-flow state is not required 001xx0 AF1x AF2x 01xx10 AF3x 11xx10 More scalable than IntServ AF4x 1xxx10 3 2 1 BE  Class encoded in IP header via  Best Effort (BE) DiffServ Code Point (DSCP)  Expedited Forwarding (EF)  Minimal delay & loss  Edge router …  Assured Forwarding (AF)  Classifies packets to DifServ classes  4 classes  3 drop precedence’s each  DSCP identifies Per Hop Behavior (PHB) Workshop, 17 Next-Generation Systems & Networks th  12 possibilities total July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 79
    80. 80. Metanoia, Inc. Critical Systems Thinking™Differentiated Services Architecture Diffserv Domain Core Functions Edge Functions EF Traffic Conditioning Colored packet Strict Meter (marked DSCP) Priority Aggregate AF PHBs Classifier Marker Shaper Scheduling BE WFQ Queueing Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 80
    81. 81. Metanoia, Inc.MPLS Support of DiffServ: Critical Systems Thinking™Mapping DSCPs to LSPs (or labels) Map DSCP  EXP bits in MPLS “shim” header  6 DS bits (64 PHBs) and only 3 EXP bits (8 classes)!  Complete mapping is infeasible  For many practical cases, 8 PHBs may suffice IP Header MPLS “shim” header 6 bits DSCP DSCP Label EXP S TTL DS byte 3 bits Results in an LSP called an E-LSP Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 81
    82. 82. Metanoia, Inc.MPLS Support of DiffServ: Critical Systems Thinking™Mapping DSCPs to LSPs (or labels) Map {PHB, FEC}  MPLS Label  That is, provide the info. in the label itself!  Requires enhancing the label distribution protocols  Use EXP bits for drop precedence  That is to determine different PHBs of a PHB scheduling class DS class drop precedence 6 bits DS class: EF, AFx DSCP DSCP Label EXP S TTL DS byte 3 bits IP Header MPLS “shim” header Results in an LSP called an L-LSP Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 82
    83. 83. Metanoia, Inc.Critical Systems Thinking™ Conclusions and Discussion
    84. 84. Metanoia, Inc. Critical Systems Thinking™Conclusions Ethernet poised to be dominant choice in metro networks  Reduces capex and opex for providers  Enables new revenue generating services 802.1ad provider bridge with OAM of 802.1ag …  … a choice at the edge Two architectures emerging for Ethernet in the metro core  Provider Backbone Transport (PBT)  IP/MPLS-based L2 VPNs Next-Generation Systems & Networks Workshop, 17th July. ©Copyright 2007All Rights Reserved 2007, Bangalore, India 84
    85. 85. Metanoia, Inc.Critical Systems Thinking™ Thank You! Questions?

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