RST _06_2002_X 2002, Cisco Systems, Inc. All rights reserved. 1

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3 Deploying L2 Transport and Tunneling Technologies

4 Andy Li Technical Marketing Engineer High-End Routing BU

5 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Implementer s Notes Summary Q & A

6 The Facts First: Current Major Access Methods Billions $US Y E A R Worldwide L2 Access Market Forecasts* Vertical Systems Group 2001 URL:// ATM 37% CAGR Frame Relay 19% CAGR Leased Line 2% CAGR *NB. New and Emerging Access Methods e.g. Metro Ethernet, Broadband Wireless etc. not projected here but supported by Unified VPN

7 VPN Market Drivers Worldwide L2 Access Market Forecasts* $ $ ILECs PTTs VPN IXCs ISPs Enterprises

8 VPN Market Drivers ILECs PTTs VPN Strategy Reduce CAPEX, OPEX via migration to converged MPLS & IP Backbones or current invested backbones while maintaining existing L2 revenue streams Capitalize on de-regulation via expansion and global reach of MPLS & IP Lucrative incremental MPLS service offerings, e.g., Firewalls, Content Management

9 VPN Market Drivers Leverage investment made in MPLS & IP backbone Obtain L2 services market share Provide solution for emerging large markets (example: Metro Ethernet) VPN ISPs IXCs

10 VPN Market Drivers Internally Managed: Simplify creation of secure (IPsec) Intranets and Extranets Outsourced VPNs: Flexible demarcations & cost effectiveness Full integration of Remote access VPNS VPN Enterprises

11 VPN Deployments Today: Technology & VPN Diversity Access Different Access Technologies Different Core Solutions Only Partial Integration Access IP / IPsec MPLS or IP IP / IPsec FR / ATM Broadband ATM FR / ATM Broadband Ethernet SONET Ethernet

12 Deployments Utilizing L2 Tunneling Technologies Access Different Access Technologies Unified Core Solutions Complete Integration Access IP / IPsec MPLS or IP IP / IPsec FR / ATM Broadband FR / ATM Broadband Ethernet Ethernet

13 Requirements to Address VPN Markets Flexibility to transport any L2 VPN service across a backbone of choice; ATM, MPLS or IP End-to-end Transport - not just Termination Flexible demarc - Customer/subscriber managed, Managed CPE, Provider Edge Standards-based solutions Ease of Deployment, Provisioning and Billing Scalable, dynamic deployment (control plane)

14 Agenda Requirements for L2 Transport Characteristics of L2 Transport Asynchronous Transfer Mode (ATM) Frame Relay (FR) chdlc & PPP Ethernet & 802.1Q Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Implementer s Notes Summary Q & A

15 Cisco L2 Transport Characteristics 2 Open standards based technologies L2TPv3 Standards track (likely, Q1CY03 IETF ratification) AToM Based on draft-martini (informational track, most widely adopted point-to-point technology for L2 MPLS Transport) Core Independent - Native support for both IP and MPLS transports L2 Access - Support for Frame Relay, Ethernet, ATM, 802.1Q (VLAN), POS, PPP and HDLC. Key Platforms C7200, C7500, C7600, C10720 and C12000

16 ATM Characteristics Header Payload GFC VPI VCI PT CLP HEC Technology: WAN-oriented, Point-to-Point, VC-based Multiplex multiple VCs onto a given physical link GFC - Generic Flow Control VPI - Virtual Path Identifier VCI - Virtual Channel Identifie PT - Payload Type CLP - Cell Loss Priority HEC - Header Error Check Predictable Delay Characteristics through fixed header / payload size Up to 622Mbps Simple Congestion Notification Applications: Native ATM Services, Frame-Relay Interworking (FRF.8) Telephony / Voice / Video

17 Frame Relay Characteristics 1 2 Variable ( 0 ~ 4096) 2 1 Flag Header L3 Datagram (Data) FCS Flag DLCI C/R EA echnology: DLCI FECN BECN WAN-oriented, Point-to-Point, Point-to-Multipoint Multiplexing up to 1024 virtual circuits per port DE EA DLCI Data Link Conn. Identifier C/R Command Response EA Extended Address Indicator FECN Forward Explicit Congestion Notification BECN Backward Explicit Congestion Notification DE Discard Eligibility Some Delay Control with Link Fragmentation & Interleaving & CIR Up to 45Mbps / Simple Congestion Notification pplications: Common Enterprise WAN Infrastructure Voice / Video / Data (FRF.12, FRF.16)

18 chdlc & PPP Characteristics Variable 2 1 Flag Address Control NLPID L3 Datagram FCS Flag Cisco Frame echnology: WAN-oriented, Point-to-Point, Leased Line No Multiplexing capabilities per port Up to 45Mbps Congestion Concept doesn t exist Flag Start Frame Delimiter (0x7E) Address Broadcast or Unicast Control Left as 0x00 NLPID 2bytes, indicates Network Layer Protocol ID (ex. 0x0800 IP) Some Delay Control with Multilink PPP & Link Fragmentation & Interleaving pplications: Common Enterprise WAN Infrastructure Data friendly / Voice (VoIP) & Video possible, with knobs

19 Ethernet & 802.1Q Characteristics Bytes reamble SFD DA SA TPID TCI Ethertype Data FCS Technology: Broadcast oriented, LAN technology Up to 10Gbps Random Delay = Data-specific, best effort traffic, variable payload size Multiplex user traffic with DOT1Q encapsulation (VLANs) TCI Contains information for Priority, CFI, and 12bit VLAN ID Applications: Data Transport & Metro Area Networking (MAN) VLANs for Workgroup / Administrative isolation IEEE Q Encapsulation DA Destination MAC Address SA Source MAC Address TPID Tag Protocol Identifier (0x8100) TCI Tag Control Information

20 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Network Management & Provisioning Summary Q & A

21 IETF Standardization Activity IETF working group PWE3 Pseudo Wire Emulation Edge to Edge ; Requirements detailed in draft-ietf-pwe3-requirements Develop standards for the encapsulation & service emulation of pseudo wires Across a packet switched backbone Focused on Point-to-Point circuit emulation PSN tunnel -> GRE, MPLS, L2TP Service -> Ethernet, ATM, PPP, FR, HDLC and so on..

22 Pseudo Wire Emulation Basics Present the appearance of 2 Customer Edge (CEs) devices connected natively without awareness of an intermediary network. Enable the transport of a Layer 2 PDUs across the Packet Switched Network (PSN) transparently. Provide mechanisms for failure notification to devices using the pseudo-wire (eg. LMI interworking) Provide configurable basics of a native service (eg. MTU, speed, etc.) Allow for the establishment of routing protocol adjacencies across a pseudo-wire. Will exert no controls on the underlying PSN with the exception of applying DiffServ Codepoints at the tunnel endpoints. draft-ietf-pwe3-requirements

23 Pseudo Wire Reference Model Customer Site PSN Tunnel Customer Site PWES PE Pseudo Wires PE PWES Customer Site PWES PWES Customer Site Emulated Service A pseudo-wire (PW) is a connection between two provider edge (PE) devices which connects two pseudo-wire end-services (PWESs) of the same type Service Types: Ethernet 802.1Q (VLAN) ATM VC or VP PWES HDLC PPP Frame Relay VC

24 Pseudo Wire Basic Building Blocks Control Channel Scale through: Session Management, Error Notification, L2 Access management interworking, etc. Required Components Transport Component This is the delivery header of the encapsulated packet. This can be a Label (MPLS) or an IP Header. (Typically the IP address of the Loopback interface on Provider Edge (PE) routers. Tunneling Component A Unique identifier used to identify a particular circuit / port on a given PE. (VC Label or VC ID) L2 PDU The Layer 2 PDU that is the subject of transport (I.e. traffic received from the Customer Edge router, typically Ethernet, Frame Relay, HDLC frames,..etc.) Connectivity between participating PEs assumed; verified through ICMP ping.

25 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Network Management & Provisioning Summary Q & A

26 Introducing AToM AToM Any Transport over MPLS (AToM) allows a pair of routers connected via an MPLS network to provide high-speed transparent Layer 2 connectivity between a pair of interfaces. This functionality can be used to build Layer 2 Virtual Private Networks (VPNs) or to support legacy network migration.

27 Layer-2 Transport across MPLS Data Plane Two relevant drafts by Luca Martini draft-martini-l2circuit-trans-mpls describes label distribution mechanisms for VC labels draft-martini-l2circuit-encap-mpls describes emulated VC encapsulation mechanisms Layer 2 Transport Options: Frame Relay ATM AAL5 & ATM Cell Relay Ethernet, 802.1q (VLAN) POS TDM, Cisco HDLC & PPP Control Plane

28 Layer-2 Transport across MPLS Control Channel Transport Component Tunneling Component L2 PDU (Emulated) Directed LDP Used for VC-Label Negotiation, Withdrawal, Error Notification Emulated Circuits have 3 layers of encapsulation Tunnel Header (Tunnel Label) to get PDU from ingress to egress PE; could be an MPLS label, GRE tunnel, L2TP tunnel Demultiplexer field (VC Label) to identify individual circuits within a tunnel; could be an MPLS label, L2TPv3 header, GRE Key, etc. Emulated VC encapsulation (Control Word) information on enclosed Layer-2 PDU; implemented as a 32-bit control word

29 Negotiating Circuit Identification VC Information Exchange VC labels are exchanged across a directed LDP session between PE routers Carried in Generic Label TLV within LDP Label Mapping Message (RFC3036 -LDP) New LDP FEC element defined to carry VC information FEC element type 128 Virtual Circuit FEC Element ; Carried within LDP Label Mapping Message VC information exchanged using Downstream Unsolicited label distribution procedures Described in draft-martini-l2circuit-trans-mpls

30 Virtual Circuit FEC Element VC TLV (0x80) C VC-type VC info length Group ID VC ID Interface Parameters C: Control Word (1 bit) Control word present if bit set VC-type (15 bits) - Type of VC e.g FR, ATM, VLAN, Ethernet, PPP, HDLC VC info length (8 bits) Length of VCID field and interface parameters Group ID (32 bits) Represents a groups of VCs. Can be used for mass label withdrawal VC ID (32 bits) Connection identifier used in conjunction with the VC-type to identify a particular VC Interface Parameters (Variable) Edge facing interface parameters, such as MTU

31 VC Label Mapping Composition Label Message (0x0400) 0 FEC TLV (0x0100) Length C TLV (0x80) 0 Message ID VC Type Group ID VC ID Message Length VC Info Length LDP Label Mapping Message (Specified in RFC 3036) FEC TLV Header (Specified in RFC 3036) Virtual Circuit FEC Element (Specified in draft-martini martini-l2circuit-trans-mpls) I/F Parameters 0 Generic Label (0x0200) Length Label TLV Header (Specified in RFC 3036) Label Optional Parameters

32 Layer-2 Transport Control Word Tunnel Label Tunnel Label (LDP or RSVP) EXP 0 TTL VC Label VC Label (VC) EXP 1 TTL (set to 2) Control Word Rsvd Flags 0 0 Length Sequence number Layer-2 2 PDU When transporting layer-2 protocols over an IP or MPLS backbone: The sequence of the packets may need to be preserved; Small packets may need to be padded if the minimum MTU of the medium is larger than actual packet size; Control bits carried in header of Layer-2 frame may Control Word Encap. Required ATM No AAL5 Yes Eth Yes FR Yes HDLC No PPP No

33 AToM Label Distribution & Usage Customer Site TUNNEL LSP Customer Site PE DIRECTED LDP PE Customer Site TUNNEL LSP Customer Site Tunnel LSPs between PE routers to transport PW PDU from PE to PE using tunnel labels Directed LDP session between PE routers to exchange VC information, such as VC labels and control information

34 AToM Label Mapping Exchange CE1 3. PE1 allocates VC label for new interface & binds to configured VCID 1. L2 transport route entered on ingress PE PE1 4. PE1 sends label mapping message containing VC FEC TLV & VC label TLV 2. PE1 starts LDP session with PE2 if one does not already exist PE2 PE2 repeats steps 1-5 so that bi-directional label/vcid mappings are established CE 5. PE2 receives VC FEC TLV & VC label TLV that matches local VCID Tunnel Label VC Label PDU Bi-directional Label/VCID mapping exchange

35 VC Label Withdrawal Procedures If a PE router detects a condition that affects norma service it MUST withdraw the corresponding VC label Through the use of LDP signalling A PE router may provide circuit status signalling FR MUST through the use of LMI procedures; ATM SHOULD through the use of ILMI procedures LDP Label Withdraw VCID 320 VC Label 16 Circuit Status Signalling PE1 PE2 MPLS Layer-2 Circuit

36 AToM Summary AToM is a method for transporting L2 PDUs across and MPLS based PSNs AToM uses Directed LDP sessions to exchange VC Labels between participating peers. AToM can use an optional Control Word to preserve information in transported PDUs AToM provides interworking with access service management protocols to maintain VC status consistency (i.e. label withdrawal in the event of edge service loss, etc.)

37 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Implementer s Notes Summary Q & A22

38 Introducing L2TPv3 L2TPv3 The Layer 2 Tunneling Protocol version 3 (L2TPv3) allows a pair of routers connected via an IP network to provide high-speed transparent Layer 2 connectivity between a pair of interfaces. This functionality can be used to build Layer 2 VPNs or to support legacy network migration.

39 Layer 2 Tunneling Protocol version 3 Frame Relay ATM Leased Line Ethernet L2TPv3 IP Core Frame Relay ATM Leased Line Ethernet L2TPv3 for customers that prefer a native IP network Provides ability to transport layer 2 traffic across IP packetbased core networks Based on a well-established lineage of protocols: L2TPv2 and pre-standards Cisco innovation Universal Transport Interface (UTI) A standards track open architecture allows extensibility to many transport types Efficient header for high performance decapsulation Configuration on edge routers only

40 Layer-2 Transport over IP Control Channel L2TP Control Channel Used for Session ID Negotiation, Withdrawal, Error Notification Emulated Circuits have 3 layers of encapsulation Transport omponent Tunneling omponent L2 PDU Delivery Header (IPv4 Header) to get PDU from ingress to egress PE; could be an MPLS label, GRE tunnel, L2TP tunnel Demultiplexer field (L2TPv3 Header) to identify individual circuits within a tunnel; (4 byte Session ID + Optional 8 byte Cookie) L2 Specific Sublayer + Payload (Layer 2 PDU) Basic Priority & Sequence Support L2 Payload:ATM, HDLC, PPP, Ethernet, Frame Relay, etc.

41 Negotiating Circuit Identification VC Information Exchange Optional Control Connection provides scalable session negotiation and reliable VC management Keepalive (Hellos) Tunnel authentication Session IDs are negotiated between L2TP Endpoints Negotiated in L2TPv3 Control Messages (ICRQ, ICRP, ICCN), and applied to L2TPv3 Data Messages Attribute Value Pairs (AVPs) are used to describe the session and provide optional parameters Described in draft-ietf-l2tpext-l2tp-base-02.txt

42 2TPv3 ontrol Messages ontrol message header format: (23)S Session ID (0x0000) T L x x S x xx x xx x Version Length Control Connection ID Ns Nr T Set to 1, indicates this is a control message L, S For a control message, this must be set to 1 indicating the presence of Length & Sequence fields x Reserved for future extensions. Ver Indicates which version of L2TP is in use. This field must be set to 3. Length Indicates the total size of the control message in octets, starting with the T bit. Control Connection ID A locally significant ID, it will the peer s ID not it s own.

43 2TPv3 ata Messages Delivery Header (20 Bytes) L2TPv3 Header L2 Specific Sublayer Layer 2 PDU (variable) Session ID (4 Bytes) Session Cookie (0 8 Bytes) Delivery header - The delivery header is the header needed to carry the L2TPv3 packet across the delivery network. This is an IPv4 header. The delivery header is 20 bytes. L2TPv3 header - The L2TPv3 payload independent header contains the necessary and sufficient information needed to uniquely identify the tunnel context at the de-encapsulation point. The payload independent header is 12 bytes. Payload - Payload to be transported by L2TPv3. It may be a link layer frame or a network layer packet.

44 Default L2-Sublayer P S x x x x xx Sequence Number PW emulation enhancements (optional): (P)riority Used to give higher priority to PW packets that shouldn t be dropped in congestion environments. (S)equencing - Indicates the presence of sequence numbers and can be used in services such as ATM / Frame-Relay, etc. (2^24 Looping Counter) (x) Reserved

45 L2TPv3 Session Negotiation CE1 3. PE1 requests a call to be setup from PE2. (ICRQ,ICRN) 1. Xconnected circuit transitions to an active state PE1 4. PE2 replies to the request from PE1 and confirms the call should be processed (ICRP) 2. PE1 starts a control connection with PE2 if one doesn t already exist. (SCCRQ, SCCRP, SCCRN) PE2 IC[xx] messages are exchanged for each new PW that is provisioned. CE 5. Negotiated Session IDs are now prepended to the PW and PDUs can be forwarded. IPv4 Header L2TPv3 Header PDU Bi-directional Session ID exchange initiated by one of the LCCEs

46 L2TPv3 Summary L2TPv3 is a method for transporting L2 PDUs across and Native IP based PSNs L2TPv3 uses a reliable Control Connection to create and manage Session IDs for Pseudo Wire muxing. L2TPv3 can use optionally provide Sequencing, Padding and Priority support through use of an L2 Specific Sublayer. L2TPv3 s control channel can provide LMI interworking with access service management protocols to maintain VC status consistency (i.e. Call Disconnect Notification (CDN) in the event of edge service loss, etc.)

47 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Implementer s Notes Summary Q & A

48 Applications of L2 Transport Technologies Applications: EoMPLS with QoS mapping FRoMPLS with Policing HDLC (Virtual Leased Line) with L2TPv3

49 Applications EoMPLS w / QoS Mapping ain Data Center VLAN 18 & 95 Remote Workgroup FE Internet GE 802.1Q Logical workgroups PE 3 PE 1 MPLS Core PE 2 FE GE Best Effort workgroups (VLAN 18) High priority traffic (VLAN 95) Optional L3 MPLS VPN Services equirement: The customer needs transparent lan services between several buildings in a Metropolitan areas to maintain workgroup and data center logical connectivity. High-priority application traffic needs preferential treatment. olution: The Service Provider can utilize MPLS core to transport VLAN traffic between sites. enefit: Time to market, leveraged infrastructure, customer retention.

50 Applications EoMPLS w / QoS Mapping 3 Configuration: nterface loopback0 ip address /32 pls label protocol ldp pls ldp router-id loopback0 force nterface GigE1/0.18 encapsulation dot1q 18 mpls l2transport route service-policy dot1q_lowpri_pmap nterface GigE1/0.95 encapsulation dot1q 95 mpls l2transport route service-policy dot1q_highpri_pmap PE1 Configuration: interface loopback0 ip address /32! mpls label protocol ldp mpls ldp router-id loopback0 force! interface FastEthernet1/0.18 encapsulation dot1q 18 mpls l2transport route service-policy dot1q_lowpri_pmap interface FastEthernet1/0.95 encapsulation dot1q 95 mpls l2transport route service-policy dot1q_highpri_pmap ain Data Center VLAN 18 & 95 FE Remote Site VC ID must match! GE PE 3 PE 1 VC ID must be unique on each router 2.1Q Workgroups MPLS Core Preamble, SFD, and FCS are stripped!

51 Applications EoMPLS w / QoS Mapping If the experimental bit mapping is not explicitly specified, the default will be a direct mapping of the user priority bits to the experimental bits. Class-maps class-map class-default Access lists, input interface, protocol Class-default Note: class-default doesn t need to be defined as it matches on all packets. Policy-maps Bandwidth, random-detect, queuelimit policy-map dot1q_highpri_pmap class class-default set mpls exp 5 policy-map dot1q_lowpri_pmap class class-default set mpls exp 0 Service-maps Input, output Interface GigE1/0.18 encapsulation dot1q 18 service-policy input dot1q_lowpri_pmap interface GigE1/0.95 encapsulation dot1q 100 service-policy input dot1q_highpri_pmap

52 Applications FRoMPLS w / Policing 256K Frame Relay AToM Tunnel Endpoints ATM CE 1 512K rate-limited DLCI 100 PE 1 MPLS Core AToM PE 2 CE 1 512K rate-limited DLCI 52 HQ DS-3 Frame Relay Trunk 384K Frame Relay CE 1 Requirement: The customer requires Frame Relay connectivity at sites in Europe. The Service Provider has a U.S. based Frame Relay network, but an MPLS based International network (or partnered.) Solution: The Service Provider can utilize the MPLS core to transport international Frame Relay back to corporate hub sites. Benefit: Time to market, leveraged infrastructure, customer retention.

53 Applications FRoMPLS w / Policing 1 Configuration: ame-relay switching terface Serial3/1 ncapsulation frame-relay rame-relay interface-dlci 100 switched class FR_512K_Inbound rame-relay policing nnect PW_EMEA serial3/1 100 l2transport pls l2transport route PE2 Configuration: frame-relay switching! interface Serial3/1 encapsulation frame-relay frame-relay interface-dlci 52 switched class FR_512K_Inbound frame-relay policing! connect PW_EMEA serial3/1 52 l2transpor mpls l2transport route K policed DLCI 100 MPLS Core CE 1 ATM To HQ Site PE 1 AToM PE 2 512K policed DLCI 52 The control word is Required, all other header components are stripped and control information (FECN, BECN, DE, C/R) is copied and preserved E2E.

54 Applications FRoMPLS w / Policing frame-relay policing Access lists, input interface, protocol Class-default Interface ser3/1 frame-relay policing Note: enables this feature on the main interface Map-class CIR, Be, Bc, Tc, EIR map-class FR_512K_Inbound frame-relay cir in frame-relay bc in frame-relay tc 1000 Service-maps Input, output 12.0(17)S Interface Serial3/1 frame-relay policing frame-relay intf-type dce frame-relay interface-dlci 1000 switched class FR_512K_Inbound Note: this is what allows the policing to be enabled on a per DLCI basis

55 Applications FRoMPLS w / Policing Frame Relay Connection Types: Port to Port Switching DLCI-to-DLCI Switching Current Support Encapsulation Support: Cisco, IETF (RFC1490) Does not require like encaps on both sides LMI Support: Cisco, ANSI, Q933a DLCI-to-DLCI, LMI types can differ Port-to-Port, LMI must be the same

56 Applications HDLC w / L2TPv3 (virtual leased line) Sites using HDLC Leased Line Service Sites using HDLC Leased Line Service PE1 IP Core PE2 CE 2 CE 1 CE1 CE TDM Core New Circuit Path Old Circuit Path Requirement: The Service Provider wishes to take advantage of high bandwidth links and begin decommissioning their TDM network. Solution: The Service Provider can utilize the IP core of their data network and offer the same leased line services to customers. Benefit: Reduced OPEX, leveraged infrastructure, network consolidation, potential revenue increase through incremental bandwidth.

57 Applications HDLC w / L2TPv3 (virtual leased line) 1 Configuration: terface Loopback0 p address tp-class L2TPv3_Control_Tweaks ostname PE1 assword 0 cisco ookie size 8 eudowire-class L2TPv3_1 ncapsulation l2tpv3 equencing both p local interface Loopback0 p pmtu terface Serial3/1 ncapsulation hdlc connect pw-class L2TPv3_1 PE2 Configuration: interface Loopback0 ip address ! l2tp-class L2TPv3_Control_Tweaks hostname PE2 password 0 cisco cookie size 8! pseudowire-class L2TPv3_1 encapsulation l2tpv3 sequencing both ip local interface Loopback0 ip pmtu! interface Serial3/1 encapsulation hdlc xconnect pw-class L2TPv3_1 IP Core Flags and FCS are stripped PE 1 L2TPv3 PE 2 If PPP is configured on the CEs the network acts transparent to mgmt!

58 Applications HDLC w / L2TPv3 (virtual leased line) TPv3 Configuration Components: Pseudowire Configuration - Serves as a template for PWs - Tunneling mechanism - Data encapsulation type, etc. 12.0(23)S Pseudowire-class L2TPv3_Default encapsulation l2tpv3 protocol l2tpv3 sequencing both Good for Frame Relay ip local interface loopback0 ip pmtu ip tos reflect Protocol Configuration - Defines the Control Plane - Used to tweak defaults Interface Configuration - Xconnect is defined - DLCI, VLAN, PVC information. l2tp-class L2TPv3_Control_Tweaks hostname PE1 password cisco cookie size 8 hello 90 Interface Serial3/0 no ip address encapsulation hdlc xconnect pw-class L2TPv3_Default

59 Applications Summary PWEs can be used in many more scenarios. CEs can optionally use IPsec for added Security L2TPv3 and AToM are flexible, easy to implement protocols. Documentation online for detailed verification and troubleshooting commands.

60 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Implementer's Notes Summary Q & A

61 Implementers Notes General MTU Calculation: It is important to calculate the max MTU for all links in the network. Supported via ip pmtu (L2TPv3) command provides ICMP notification to the offending sender. In AToM mtu <x> or mpls mtu <x> Core MTU >= (Edge MTU + Transport header + AToM header + (MPLS label stack * MPLS label size)) Sequencing: Various conditions cause packet reordering to occur Sequencing support may will detect and drop such packets, re-sequencing isn t currently supported. MQC Support: 12.0S Will support policing (via match-dlci) on the 7200 / 7500 platforms 12.2S, and 12.2T extends full MQC support and expand platform group.

62 Implementers Notes General Keepalives: QoS: Customer Edge to Customer Edge (CE-CE) May be employed and will be tunneled along with other data Customer Edge to Provider Edge (CE-PE) No requirement, service should be transparent Provider Edge to Provider Edge (PE-PE) Tunnel Endpoints L2TPv3 Control Connection can be implemented for this In a down event, (L2TPv3 Hellos failure) The PEs will teardown all manual and dynamic sessions 2 Possibilities: - IP ToS Setting or Reflection Currently Supported q user priority mapping to IP ToS or MPLS EXP Some Support

63 Implementers Notes UTI to L2TPv3 Migration Designed for Migration from pre-12.0(23)s: e-12.0(23)s UTI (Tunnel-based CLI) to Xconnect (Session-based CLI) Generation of Pseudowire Class for attachment circuits using common parameters (ex: Loopback, TTL, ToS, etc.) Sub I/F are converted to connect-based CLI and removed from main interface. terface <Tunnel name> o ip address unnel source <source interface> unnel destination <dest ip address> unnel mode uti raw l2tp unnel key <key value> unnel tos <tos value> unnel ttl <ttl vlaue> unnel uti l2tp high-key <high key value> unnel uti l2tp local-session <local id> unnel uti l2tp remote-session <remote id> terface FastEthernet1/0 o ip address ti-tunnel <Tunnel name> 12.0(23)S pseudowire-class <Tunnel name> encapsulation l2tpv3 protocol none ip local interface <source interface> ip tos <tos value> ip ttl <ttl value> ip dfbit set interface FastEthernet1/0 xconnect <dest ip addr> 100 encapsulation l2tpv3 manual pw-class <Tunnel name> l2tp id <local id> <remote id> l2tp cookie local 8 <key value> <high key value> l2tp cookie remote 8 <key value> <high key value

64 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Implementer s Notes Summary Q & A

65 Summary L2 Transport extends the functionality of PSNs through the creation of or extension of edge services. L2 Transport assists in reducing costs for OPEX and CAPEX in Service Provider networks. Cisco provides open standards based options for MPLS and Native IP networks through AToM and L2TPv3.

66 Agenda Requirements for L2 Transport Characteristics of L2 Transport Pseudo-Wire Emulation L2 Transport for MPLS Networks L2 Transport for IP Networks Applications of L2 Transport Technologies Implementer s Notes Summary Q & A

67 Follow on Sessions RST-150 Introduction to MPLS RST-251 Deploying MPLS Traffic Engineering RST-253 Deploying MPLS VPNs RST-450 Advanced Concepts and Developments in MPLS

68 References AToM (Martini): L2TPv3: Pseudowire Specific:

69 Terms & Acronyms AVP - Attribute Value Pair. Multiple AVPs make up L2TPv3 Control messages. (Same as TLVs in Martini specs) CE - Customer Edge. This is the customer equipment making a direct connection to the Service Provider's equipment (PE). CIR - Commited Information Rate. In Frame Relay, the minimum average data rate provided to the customer. Control Connection - A reliable channel that is used to establish, maintain and remove L2TP sessions (directed-ldp in AToM) Control Message - An L2TP message used by the Control Connection Data Message - Message used by the data channel Directed LDP - An extended LDP session used to connected PEs that aren't directly adjacent. DLCI - Data Link Connection Identifier. A value between 0 and 1023 used to identify a circuit on Frame Relay enabled port. LCCE - L2TP Control Connection Endpoint. Defined as one end of the L2TP control connection. LDP - Label Distribution Protocol. RFC3036. One over several protocols available to establish LSPs. LSP - Label Switched Path. The path a MPLS encapsulated packets take through the core. LSR - Label Switched Router. A node participating in an MPLS core. MTU - Maximum Transer Unit. Maximum size a frame can be for a Layer 2 specification. PDU - Protocol Datagram Unit. PDU refers to the Layer 2 data that will be forwarded across the segment (frame). PE - Provider Edge. This is the a service provider equipment making a direct connection to the Customer's equipment (CE).

70 Terms & Acronyms Pseudo-wire PDU - A PDU sent on the PW that contains all of the necessary elements (control and data) to provide the service. PSN - Packet Switched Network. Native IP or Multiprotocol Label Switched for this discussion. PW - Pseudo-Wire. A mechanism that carries essential elements of the an emulated service over the PSN. PWE3 - Pseudowire Emulation End-to-End (IETF working group devoted to standardization of PWE Services) PWES - Pseudowire Edge Service (Common attachment technologies, such as ATM, Frame Relay, HDLC, etc.) Session - Created by an Control Connection. Specifically, a one-to-one mapping of circuitto-pseudowire. TLV - Type-Length-Value. Used to define optional parameters used in LDP-Label Mapping messages, comparable to AVPs.

71 Cisco References Unified VPN Suite ( Learn About Unified VPN Suite View Unified VPN Suite Technical Documents View Unified VPN Suite Presentations View Unified VPN Suite Press Releases Read Unified VPN Suite Articles and Reports View Related URLs View Unified VPN Suite Events

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