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Drivers for Transport Network Evolution

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Presentation on theme: "Drivers for Transport Network Evolution"— Presentation transcript:

1 Carrier Ethernet Technologies and Test Applications Reza Vaez-Ghaemi, Ph.D. November 2008

2 Drivers for Transport Network Evolution
Triple Play services Business services Mobile backhauling Carrier-class performance (SLA guarantees) Flexible, cost-effective BB Access, Ethernet and Photonics technologies

3 Carrier Ethernet Requirements
Native Ethernet lacks key capabilities needed for a robust metro core network technology Ethernet is continuously being enhanced with key features for carrier grade performance such as: QoS: service differentiation and prioritization Scalability: granularity and number of services OAM: Monitoring, loopback Protection: 50ms path protection TDM support OAM QoS Protection Carrier Ethernet TDM Support Scalability

4 Basic structure of Ethernet Network
Customer Provider Transmission technique Customer Edge Equipment Provider Edge Equipment LAN CE PE PB Packet oriented Ethernet Switching technique Access Backbone, Core WAN, Metro Network Access

5 Connect networks– Direct, multiple and virtual
LAN CE PE Eth Backbone VPN VPN realized with native Ethernet VLAN (802.1p/q); Q-in-Q (802.1ad); MAC-in-MAC (802.1ah) Switching in the BB by Ethernet transparent switching VLAN tag serves as filter, not as switching information. VPN separation only in the access switch VPN realized with an IP Network VPLS (Virtual Private LAN Service); MPLS (Multiprotocol Label Switching) Switching in the BB by MPLS label VPN separation in the whole BB by LSP (Label Switched Path)

6 VLAN tagging - why VLAN Q in Q
VLAN is a filter function – logical separation of MAC frames MAC frames are only valid for dedicated egresses Necessary to block frame distribution to everybody in case of Broadcast function Used for layer 2 switch based networks Q in Q Necessary if customer also uses VLAN tags Inner tag = Customer tag, Outer tag = Service tag MAC in MAC Provider Backbone Bridges PBB Reduces the adress table of provider backbone switches Only MAC adresses of all provider edge equipment are to be learned

7 Virtual Local Area Network (VLAN) – idea
The idea of VLAN is to segment networks into logical groups rather than physical conditions. provider device VLAN #1 VLAN #2 VLAN #3 different offices management Logical segmentation development controlling Physical segmentation

8 VLAN configuration and operation – Q-in-Q
802.1ad: Q-in-Q (VLAN-Stacking): Is necessary, when also the customer is using VLAN in his network. Customer C-LAN CE PE Provider S-LAN PE CE Customer C-LAN Customer: With VLANs VID MAC IP SVLAN MAC CVLAN IP VID MAC IP Switching in the provider net: SVLAN tag has no switching function. The SVLAN only hides the CVLAN. The MAC addresses of the customer devices remains visible and are needed for switching. Still transparent switching and flooding based on the customer Ethernet addresses. This is a big disadvantage in large networks! Solution: A totally separate (addressing, switching, management) backbone transport network. PBBN – Provider Backbone Bridge Network (IEEE 802.1ah)


10 G.8112/Y.1371: “Interfaces for the Transport MPLS (T-MPLS) hierarchy”
What is MPLS ? G.8112/Y.1371: “Interfaces for the Transport MPLS (T-MPLS) hierarchy” Conceived to be flexibly client of all the relevant transport technologies: PDH SDH (POS) OTN G.709 (GFP) Ethernet and RPR Provides service to all types of client traffic: IP Ethernet ATM and Frame Relay PDH and SDH (circuit emulation)

11 Equipment and Terminology
MPLS-VPN Equipment and Terminology P P C LSR LSR C PE PE CE CE LSR LSR C P P C LSR LSR C - Customer Router CE - Customer Edge Router PE – Provider Edge Router P - Provider Router LSR – Label Switch Router Customer routers are refered to a C or CE routers and the provider routers facing the customer are called Provider Edge or PE routers and other provider routers are called Provider or P routers. When these routers become MPLS routers they are called Label Switch Routers or LSR. This collection of MPLS LSR’s is called a MPLS Domain.

12 Architecture: The MPLS label...
L3 header Label L2 header Label Exp S TTL 32 bits 20 3 1 8 L3 header Label 1 Label 2 Label 3 Label n L2 header Label stack MPLS label to ATM VPI/VCI to Frame Relay DLCI The MPLS label is inserted between the Layer 2 and Layer 3 header. Multiple labels can be inserted. There are usually at least two labels. The MPLS label can also be used to obtain the VPI/VCI for ATM or the DLCI for Frame Relay. The EXP field is a priority field. This value is either entered manually as part of the configuration for an interface or obtained from the priority field of the Vlan or IP priority fields. The MPLS label is inserted directly before the OSI layer 3 protocol header. Since the router only evaluates the label, the TTL counter must also be maintained in the label. Several labels can be set as a label stack, and for the next LSR only the top label (last label pushed; in the example, label n) applies: A label is pushed at the start and popped at the end of an LSP. TTL field with label stacking: If a new label is pushed onto an existing label stack, it gets the current TTL value of the label at the top stack position. If the bottom label in a label stack is popped, the last TTL value of the popped label is copied to all other labels in the stack. Another major benefit of MPLS is that an edge LSR can set up an LSP even via a VCI in an ATM network or via a DLCI in a Frame Relay network. The LSP is mapped to a VCI or DLCI. In both cases, the switching process is actually shifted to layer 2. Label: Label value TTL: Time to live Exp: Experimental use S: Stack indicator IP L L2 IP VPI/VCI IP DLCI

13 Architecture: Ingress LSR
The domain needs a way in ... Located at the edge of an MPLS domain Represents the ingress to an MPLS domain Assigns packets to an FEC Inserts the first label LSR Edge LSR LSR IP IP LSR LSR IP An IP packet enters the Edge LSR without a Label, the PE router or the Provider Edge assign a FEC and inserts the first label. The PE router used to access the MPLS domain is referred to as the Ingress router. Ingress LSR

14 Architecture: Egress LSR
… and a way out. Located at the edge of an MPLS domain Represents the egress to an MPLS domain Removes the last label and re-creates the original packet LSR Edge LSR Edge LSR IP LSR IP LSR IP The label switched packets traverse the network with Label inserted into them and the outgoing Edge LSR or Egress router removes the Label to transmit an IP packet without a label. The packet enters the MPLS network without a label and exits without a label therefore the CE routers do not need to be MPLS aware. LSR Egress

15 The need for VPLS Switched Ethernet network architectures have proven to be successful in delivering high-performance, low-cost L2 VPN multipoint services. However, as the size of these switched Ethernet networks has continued to grow, the limitations on the scalability of this architecture has become increasingly apparent. These limitations include: Limited VLAN address space per switched Ethernet domain Scalability of spanning tree protocols (IEEE 802.1d) for network redundancy and traffic engineering Ethernet MAC address learning rate, which is important to minimize broadcast traffic resulting from unknown MAC addresses. To address the limitations of both MPLS L3 VPNs and Ethernet switching, innovations in network technology for delivering multipoint connectivity services have led to the development of a new technology, which is known as Virtual Private LAN Service or VPLS.

16 What is VPLS ? Virtual private LAN service (VPLS) is an MPLS application and is used to provide multipoint to multipoint L2 VPN services. It allows geographically dispersed sites to share an Ethernet broadcast domain by connecting each site to an MPLS-based network. In contrast to Layer-2 MPLS VPNs, which allow only point-to-point layer 2 MPLS tunnels, VPLS allows a full mesh of sites, allowing any-to-any (multipoint) connectivity. Assuming our VPLS is MPLS-based, we can use Label distribution protocol (LDP) to create LSPs (mentioned in the previous chapter). VPLS can also support VLANs on the customer side of a PE, in that case, we must encapsulate a VLAN ID in each packet that is sent

17 VPLS Reference Model The customer sites are connected through a service provider network, which appears as a Layer 2 switch. Customer sites are connected to the service provider network at the Provider Edge (PE). All PEs in the network are connected together with each tunnel carrying multiple pseudo-wires. Pseudo-wires are point-to-point connections setup for each offered service between a pair of PEs.

18 MPLS and VPLS – The small difference
VPLS - Virtual Private LAN Service The customer sees his “own” Layer 2 Ethernet network. The complete Ethernet packets of the customer are transferred. PE device emulates to the CE a virtual L2 Ethernet LAN CE can be a router or an Ethernet switch. PE CE L2 Eth L3/IP +MPLS MPLS - Multiprotocol Label Switching The customer sees his “own” Layer 3 IP network. Only the IP part of the packet is transmitted. Ethernet is terminated at the PE. PE device emulates to the CE a virtual router. CE must be a router. PE CE L3 IP L3/IP +MPLS

19 T-MPLS - why T-MPLS Makes MPLS a „Carrier Class Network“: Combines the advantages of a reliable packet-based technology (MPLS) with circuit based transport networking. Based on IP/MPLS technology but simpler implementation: - removes features not relevant for connection oriented applications + addresses critical transport functionality gaps Connection oriented only Standardized by ITU-T Key enhancements: + point-to-point bi-directional LSP + end to end LSP protection (50ms) + advanced OAM support (optimal control of network resources)  lower OPEX

20 Differences MPLS and T-MPLS
MPLS uses uni-directional LSPs T-MPLS uses bi-directional LSPs (it pairs forward and backward LSPs) MPLS uses PHP (Penultimate Hop Popping): removes the MPLS label one node before the egress - to minimize router processing) T-MPLS doesn‘t use PHP MPLS uses LSP Merge: all traffic forwarded along the same path to same destination may use the same MPLS label – make OAM and perf.monitoring difficult – it‘s not connection oriented T-MPLS doesn‘t use LSP Merge MPLS uses ECMP (Equal Cost Multiple Path): it allows traffcic within one LSP to be routed along multiple NW paths – requires additional IP header and MPLS label processing and makes OAM complex T-MPLS doesn‘t use ECMP

21 T-MPLS - Positioning T-MPLS shifts itself under the packet based networks, in order to organize the “classical” transport networks. Packet based transport networks: IP Netze MPLS (= „IP-MPLS“ according IETF) Data (L2 & L3 VPN) Voice (VoIP) Internet (WEB, ) Video (IPTV, VoD) Optical transport networks: OTN, WDM, fiber TDM based transport networks: (PDH), SDH Packet based transportnetworks: Ethernet, RPR T-MPLS (= GMPLS without MPLS according ITU-T)

22 Gain of T-MPLS? Network operator Connection oriented
„Carrier Class“ packet switched system for „Carrier Grade“ MPLS Connection oriented Management, control and quality is based on proven technologies (e.g. SDH APS) Convergence of layer 2 (Ethernet) and layer 3 (IP) client signals over one packet based transport technique With GMPLS one control plane for all network layers (packet, TDM, lambda, fiber) OPEX and CAPEX lower as with IP MPLS The question remains: OPEX and CAPEX still lower as with PBB-TE? Possible responds: Depends on which infrastructure (SDH) is already available and how the further network development is planned.

23 Why MPLS-TP? Statically configure LSP/PWE via management plane Deliver OAM for LSP/PWE Consistent OAM for multi-layer networks which enables interworking of services such as LSP, PWE, and L2 Offer MPLS LSP and PWE as a transport service Manage LSP/PWE at nested levels (path, segment) Additional protection switching Congruent OAM and Traffic including LAG/ECMP

24 What is MPLS-TP? Definition of an MPLS Transport Profile (TP) within IETF MPLS standards Based on PWE3 and LSP forwarding architecture IETF MPLS architecture concepts Major concept is LSP. PW is a client.

25 LSP and OAM A segment is between MEPs
• OAM is end to end or per segment • In SDH/OTN and Ethernet segment OAM is implemented using Tandem Connection Monitoring (TCM) • The OAM in each segment is independent of any other segment • Recovery actions (Protection or restoration) are always between MEPs i.e. per segment or end to end

26 Associated Channel Level (ACH)
Generalised mechanism for carrying management / OAM information OAM capabilities : Connectivity Checks (CC) and “Connectivity Verification” (CV) Management information: Embedded Control Channel (ECC) Data Communications Network (DCN) Signalling Communication Network (SCN) APS information

27 How does it work? Processed by the pseudo-wire function on the end-points End point or Pseudo-wire stitch point Verifies the operational status of the pseudo-wire Working with the native attachment circuit technology An inter-working function with the native attachment circuit OAM. Transport and act upon native attachment circuit OAM technology


29 Why PBB? Eliminates address space scalability issue
Solves MAC table size issue Works in conjunction with 802.1ad (Q in Q)

30 What is PBB? A PBBN is its own virtual bridged local area network, which is completely under the administrative control of the backbone provider. Switching: Transparent switching and flooding based on the PE MAC addresses. By introduction of a further MAC layer (MiM) a clear separation between customers and provider results to addresses, switching and management. For data separation, PBB adds an I-tag and a B-tag. Customer data (MAC addresses, VLAN tags) are transparently transported. Multiple spanning tree enables to distribute the backbone load to several even parallel paths. Normally a MST per VLAN. MAC Addresses of PE switches Address cache Port 1: W Port 2: X Port 3: Y,Z MAC(A,B,C) MAC(S,T,U) (W) (Y) MAC(H,I) 1 3 MAC(J,K,L) 2 PB (X) (Z) PE BB-Access Backbone Access B U B W Y U I B U

31 PBB – 802.1ah detailed frame format
FCS B-SA B-DA TPID B-VID B-DEI B-PCP I-SID I-DEI I-PCP RES1 RES2 Payload 48 16 3 1 12 2 24(120) 32 B-TAG B-TCI I-TAG I-TCI B-DA, B-SA: Backbone Destination und Source Address TPID: Tag Protocol Identifier (Indication, which TCI follows. C-, S-, B, or I-TCI) B-PCP: Backbone VLAN Priority Code Point (Shows the CoS for prioritized transport.) B-DEI: Backbone VLAN Drop Eligible Indicator (Shows whether the frame can be preferred B-VID: Backbone VLAN ID dropped in overload situations.) B-TCI: Backbone TAC Control Information I-PCP: Service Instance Priority Code Point I-DEI: Service Instance Drop Eligible Indicator I-SID: Service Instance Identifier RES1/RES2: Reserved for future applications

32 PBB/PBB-TE Test Terminating PBB trunks, testers T1 and T2 perform an end-to-end layer 2 test configured with B-Tag fields in Mac in Mac format. Testers only filter on B-MAC/B-VID/(I-SID) and handle everything else in the frame as part of the payload. T1 T2 BCB-BEB Interface BCB-BEB Interface Customer 2 Site B BCB BCB Customer 1 Site A PB CB CB PB BEB BEB CB CB BCB BCB PB PB Customer 1 Site B Customer 2 Site A

33 Ethernet OAM

34 Services Connectivity Transport/Link Ethernet OAM Layers
ITU Y.1731 and MEF Services IEEE 802.1ag, ITU and MEF Connectivity EFM (IEEE802.3ah) EoSDH (ITU) EoTDM (ITU) Transport/Link

35 Ethernet OAM Standards Activities
UNI UNI 100FX Carrier NW 100FX Media Convrtr Media Convrtr Carrier Edge Carrier Edge Media Convrtr Media Convrtr 802.1aj demarcation device 802.1aj demarcation device MEF & ITU Y.1731 Service Layer OAM (UNI to UNI) IEEE 802.1ag, MEF & ITU Y.1731 Connectivity Layer OAM Access Link OAM Access Link OAM IEEE 802.3ah

36 Ethernet OAM Standards
Services and Performance (ITU Y.1731/MEF) Basic Connectivity (IEEE 802.1ag,ITU) Transport/Link (802.3ah EFM) Discovery Continuity check (keep alive) Continuity check Remote failure indication: Dying gasp, link fault & critical event Loopback (non-intrusive and intrusive) Loopback Remote, local loopback AIS/RDI/Test AIS Fault isolation Link Trace Performance monitoring with threshold alarms Performance management Status monitoring MRV 1m I think it’s worth pointing out some of the specific OAM functions that 802.3ah does and does not support. The table on the screen breaks these down into several key categories with specific examples listed within each. The thing to note, here, is that even where 802.3ah may not support a particular OAM function, an Ethernet Access equipment vendor may implement its own extension to the standard and include support for that function without compromising interoperability. It is this flexibility of the 802.3ah standard that makes it so powerful. Now we won’t take the time to discuss each item listed in the chart. Must of these I’m sure you are already familiar with. However, if there is one or two that you would like to go over in more detail, just send Andy a message via the chat window and we’ll try to cover it during the Q&A session at the end of this presentation.

37 Management Layer Comparison
Ethernet Link/Domains Link Loopback RDI Event Monitoring Signal/line quality (frames/symbols) Domains CFM Loopback (“ping”) CFM Linktrace (“traceroute”) CFM Connectivity Check SONET Line/Section/Path Line Loopback RDI Signal/line quality (BER) Section Path

38 Ethernet First Mile OAM
Why not just use IP-based management (SNMP, Telnet, etc.)? IP infrastructure must be operational and properly configured Some networks don’t use IP Security vulnerability IEEE 802.3ah OAM Provides low level Ethernet OAM functionality at FM Isolated to First Mile segment Complements SNMP and other IP-based NMS NMS can be secure and away from the user Media independent: Fiber (Active P2P or PON), Copper Uses standard Ethernet frames – slow – 10 frames/sec Backward compatible with non-802.3ah Ethernet Requires minimal configuration (almost “plug and play”)

39 Ethernet First Mile OAM
(Access Link) First Mile (Access Link) Carrier Network 802.3ah 802.3ah NMS Defines: EDD – Ethernet Demarcation Device (NID) Functions: Monitor Link performance Fault detection and notification (signaling) Loopback testing

40 Ethernet 802.3ah Protocol First Mile (Access Link) First Mile (Access Link) Carrier Network 802.3ah 802.3ah NMS Discovery – Exchange of capabilities and i.d. info Periodic state update / monitoring Link event notifications (performance threshold alarms) Remote failure notification – Link faults (Network side port) including Unidirectional Dying Gasp – catastrophic / non-recoverable failures Critical events – vendor specified events Remote Loopback Read MIB info / stats Vendor extensions

41 Management of Network Edge
UNI MAC Device Service Provider PE 802.3ah OAM MEF ELMI 802.1aj TPMR Multiple standards provide building blocks for managing the access 802.3ah OAM addresses how to manage physical from the PE to the MAC layer of the remote device MEF ELMI addresses how to manage the UNI of the remote device 802.1aj Two-Port MAC Relay addresses how to manage a potential customer demarcation device Each protocol adds some unique functionality, and (unfortunately) adds some overlap functionality with the other standards

42 IEEE 802.1aj TPMR IEEE 802.1aj Two-Port MAC Relay
Defines protocols for interactions carrier bridge and remote 2-port relay device that might be used for demarcation Uses SNMP natively over Ethernet (no IP!)*** Configuration of remote parameters*** VLAN behavior CoS and QoS characteristics of interfaces Forwarding behavior (data and L2 protocols) Status information between carrier and customer*** Utilizing IEEE 802.1ag Covers configuration and status of all aspects of remote device IF the device is a simple two-port relay forwarder Does not apply to bridges, routers, etc. which may also implement UNI or forwarding functionality Mostly intended for CARRIER owned demarcation device ***Tentatively

43 Ethernet Service OAM Being standardized by Metro Ethernet Forum and ITU (Y.1731) Builds upon IEEE 802.1ag functions by utilizing timestamps and other fields to monitor SLA metrics for Ethernet services Measures latency, jitter, loss, etc. end-to-end across any domain Used to validate SLA performance of Ethernet service across any kind of underlying network

44 Ethernet OAM Implementation
802.3ah (Access Link) Operator A Operator B 802.1ag/ Y.1731 (UNI-N to UNI-N ME) Focus on end-to-end OAM (IEEE802.1ag, ITU Y.1731) incorporating last segment OAM (IEEE802.3 ah) End-to-end service OAM: Continuity Check Loopback Performance Monitoring Frame Delay, Frame Delay Variation, Frame Loss, Availability

45 Customer End-to-End Metrics Provider End-to-End Metrics
IEEE 802.1ag CFM CFM = Connectivity Fault Management (in progress) Partitions network into hierarchical administrative domains Basic connectivity checking and troubleshooting across any domain, and across multiple domains at the same time Partitions big problem into pieces & controls visibility Service Provider Operator Operator Customer End-to-End Metrics Provider End-to-End Metrics Operator Metrics Operator Metrics

46 IEEE 802.1ag CFM Providing “ping” and “traceroute” equivalents for bridged (rather than routed) networks Loopback (= Ping): Given MAC address and VLAN tag, verify connectivity LinkTrace (= Traceroute): Given MAC address and VLAN tag, find the path between the local source and that destination Also provides continual connectivity checking (a.k.a. heartbeat) to proactively monitor end-to-end availability and packet loss

47 Continuity Check (CC) OAM
Operator A Operator B CC Sink CC OAM Frames CC Source CC OAM Defined per EVC, one-way connectivity monitoring Loss of Continuity (LOC) is declared (only at the sink side) upon 3.5 seconds without receiving CC OAM frame Loss of Continuity (LOC) is cleared upon sink receiving 2 CC OAM frames within a window of several seconds Upon CC failure Send trap Update active alarm log Update statistics Optional uplink switch-over

48 Loopback (LB) OAM Operator A Operator B LB OAM Request MEP MEP LB OAM Reply Per Link/Port: Remote loopback minimizes a false repair calls Non-intrusive loopback: Defined per EVC/service monitoring one VLAN is looped back while others continue to provide their services LB Failure is declared upon 2 sec without receiving OAM frame Upon LB failure Send trap; Update active alarm log; Update statistics Optional uplink switch-over

49 Performance Monitoring (PM) OAM
Defined per service (EVC+CoS), allows for in-service, end-to-end SLA monitoring Measured parameters Frame Delay, Frame Delay Variation, Frame Loss, Availability Performance Measurements traps Traps sent upon: {# Frames} crossing {Objective} within {Sampling Time} The above applies for both ‘Rising’ and ‘Falling’ thresholds definition Statistics are collected per 15 minutes intervals; Cyclic 96 intervals kept (24 hours)

50 Test Application Field
Analyze/Generate OAM errors/alarms Performance Measurements Loopback tests UNI Media Convrtr Carrier Edge IEEE 802.3ah MEF & ITU Y.1731 Access Link OAM IEEE 802.1ag, MEF & ITU Y.1731 Connectivity Layer OAM Service Layer OAM (UNI to UNI) 100FX . Carrier NW 802.1aj demarcation device

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