Overview of GMPLS Protocols and Standardization

Transcription

1 Overview of GMPLS Protocols and Standardization Kohei Shiomoto Abstract MPLS (multiprotocol label ing) introduced the concept of label ing in IP layer-2 networks to facilitate network operation using a path. GMPLS (Generalized MPLS) extends the label to (time division multiplexing), wavelength, and fiber ing networks to facilitate path operation in various ing networks. GMPLS protocols enable multi-vendor interoperability, ed connection service, and unified control of a multi-layer network. This article presents an overview of GMPLS protocols and standardization efforts in the Internet Engineering Task Force (IETF). 1. Label extension In MPLS (multiprotocol label ing) networks, an IP packet is labeled with an MPLS label and handled according to operations associated it. This packet handling mechanism in MPLS network is called label-ing. The label-ing concept brings about flexibility in handling packets in the network. Virtual private networks (VPNs) and traffic engineering are implemented using the label ing concept. The MPLS label is used to distinguish the VPN group. The label ed path is routed to NTT Network Service Systems Laboratories Musashino-shi, Japan shiomoto.kohei@lab.ntt.co.jp avoid congested links. MPλS (multiprotocol lambda ing) was proposed to extend MPLS technology to wavelength ing network control [1]. MPλS was extended to GMPLS to include (time division multiplexing), wavelength, and fiber ing networks. time slots, wavelengths, and fiber ports are treated as generalized labels in GMPLS, as shown in Fig GMPLS protocols In GMPLS, signaling, routing, and link management protocols are defined. The concept of ing capability is introduced in GMPLS protocols to handle various ing technologies: layer-2 Fiber #N Fiber #N Lambda Fiber Fiber #N Fiber #N (1) network (2) Lambda ing network (3) Fiber ing network Fig. 1. Label es of each bus networks. 76 NTT Technical Review

2 es,, lambda es, and fiber es. Five capabilities are defined to distinguish ing technology, as shown in Fig. 2: (packet capable), L2SC (layer-2 capable),, (lambda capable), and FSC (fiber capable). GMPLS adds various functions to MPLS to facilitate path operation in GMPLS networks. Unlike IP/MPLS networks, the control plane is separated from the data plane in, wavelength ing, and fiber ing networks. A bi-directional path is used in those networks while a uni-directional labeled path (LSP) is used in an IP/MPLS network. GMPLS adds functions for separating the control and data planes and for setting up and tearing down bidirectional LSPs. 3. Signaling RSVP-TE (resource reservation protocol traffic engineering) [2] is extended to facilitate path setup in a GMPLS network [3]. Label Request Object is extended to include type, encoding type, and G-PID (generalized protocol id), which are used to identify, wavelength ing, and fiber ing networks as shown in Fig. 3. Upstream Label Object is newly defined for bi-directional LSP setup/teardown. RSVP_HOP Object is extended to include a new class type for control and data plane FSC FSC FSC Fig. 2. GMPLS network. Generalized label request object is newly defined in RSVP message to specify the type of LSP. - LSP encoding type - Switch type - GPID - Bandwidth LSP encoding type: 1: Packet 2: Ethernet 3: ANSI/ETIS PDH 4: Reserved 5: G.707/T : Reserved 7: Digital wrapper 8: Lambda 9: Fiber 10: Reserved 11 Fiber Channel Path w/ Gen.Lab.Req Switch type: 1: -1 2: -2 3: -4 4: -5 51: 100: 150: 200: FSC GPID: 0: Unkown 5: Asynch. Map. Of E4. 26: VT/LOVC 27: STS SPE/HOVC. 30: POS scrambling, CRC-16 32: ATM map. 33: Ethernet 34: SONET/SDH 36: Digital wrapper 37: Lambda.. Router Resv Cross-connect Example of LSP between OC48c interfaces of routers. LSP encoding type = G.707/T1.105 Switch type = GPID = POS-scramble, CRC-16 Bandwidth encoding = Mbit/s Fig. 3. RSVP-TE GMPLS extensions. Vol. 2 No. 6 June

3 separation. Label Set Object and Acceptable Label Set Object are newly defined for explicit label control. Protection Object is newly defined to implement failure recovery LSP ing. 4. Routing OSPF-TE (open shortest path first-traffic engineering extensions) [4] is extended to facilitate link-state routing. Link state is flooded throughout the area of the GMPLS network. All nodes in the area of a GMPLS network learn the network topology and associated information such as available bandwidth. Link state advertisement is extended to include new sub-tlvs to carry the following information: interface ing capability descriptor (ISCD), link protection type, and shared risk link group (SRLG) as shown in Fig. 4 [5]. ISCD sub-tlv is used to identify ing capability and encoding type. The link protection type sub-tlv and SRLG sub-tlv are used to recover from a failure. 5. Link management Link management protocol (LMP) is defined for operation and maintenance of link between adjacent nodes [6]. The link between adjacent nodes consists of control and data links. A Hello packet is used to check whether the control link is alive. For data link management, summarization of multiple data links and failure localization procedures is defined [6]. The functions of LMP are shown in Fig Standardization status GMPLS is mainly being standardized by the CCAMP-WG (common control and measurement plane working group) of the Internet Engineering Task Force (IETF). CCAMP-WG is defining GMPLS protocols based on requirements documents produced by TE-WG (traffic engineering) and IPO-WG (IP optical). It also liaises with ITU (International Telecommunication Union). Figure 6 shows the recent history of standardization in IETF CCAMP- WG. RFCs (requests for comments) for basic signaling protocols have been published. RFCs for routing protocols and link management protocols are under way. The next items include failure recovery including protection and restoration, ASON (automatically ed optical network) signaling & routing, and multi-area/multi-region traffic engineering. 7. Closing remarks GMPLS is expected to introduce new services and a new operating scheme in the telecommunication industry. BoD (bandwidth on demand), optical VPN, and multi-gos/availability services could be developed (GoS: grade of service). Standardization of GMPLS protocols promotes multi-vendor interoperability and flexible network design and operation. Router Link-state view Cross connect ISC: 1: -1 2: -2 3: -4 4: -5 51: 100: 150: 200: FSC Encoding: 1: Packet 2: Ethernet 3: ANSI/ETIS PDH 4: Reserved 5: G.707/T : Reserved 7: Digital wrapper 8: Lambda (photonic) 9: Fiber 10: Reserved 11 Fiber Channel Fig. 4. OSPF-TE GMPLS extensions. 78 NTT Technical Review

4 Health check of control channel Hello packet wteststatussuccess VerifyId A,1, B,10 Control channel eteststatusack A qtest message q VerifyId w A,1 e!0!1!2 B Grouping of data link (1) Health check of control channel (2) Grouping of multiple data links (3) Verification of data link CLEAR ChannelFail LOL ChannelFail LOL A B C D ChannelFailNack ChannelFailAck Fault localization (4) Fault localization Ack: acknowlegment Nack: negative acknowledgment LOL: loss of light Fig. 5. Link management protocol (LMP). CY2001 CY2002 CY2003 CY Q 4 Q 1 Q 2 Q 3 Q 4 Q 1 Q 2 Q 3 Q 4 Q 1 Q 2 Q 3 Q 51 st (London) Aug th (SLC) 53 th (Minneapolis) 54 th (Yokohama) Dec Mar July th 56 th (Atlanta) (SF) Nov Mar th (Vienna) 58 th (Minneapolis) 59 th (Seoul) July Nov Feb. 29 Mar th (San Diego) Aug. 1 6 (Signaling, routing, LMP) Protection & restoration ASON Multi-area TE RFC 3471 (Signaling) 3472 (RSVP-TE) 3473 (CR-LDP) 3477 (RSVP-TE Unnumbered IF) 3480 (CR-LDP Unnumbered IF) Routing OSPF-TE IS-IS LMP Fig. 6. IETF standardization. Vol. 2 No. 6 June

5 References [1] D. Auduche and Y. Rekhter, Multiprotocol Lambda Switching: Combining MPLS Traffic Engineering Control with Optical Crossconnects, IEEE Commun. Mag., Vol. 39, Issue 3, pp , [2] D. Awduche, L. Berger, D. Gan, T. Li, V. Srinivasan, and G. Swallow, RSVP-TE: Extensions to RSVP for LSP Tunnels, RFC 3209, [3] L. Berger (ed.), Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions, RFC 3473, [4] D. Katz, K. Kompella, and D. Yeung, Traffic Engineering (TE) Extensions to OSPF Version 2, RFC 3630, [5] K. Kompella, and Y. Rehkter (eds.), OSPF Extensions in Support of Generalized Multi-Protocol Label Switching, Internet-draft <draftietf-ccamp-ospf-gmpls-extensions-12.txt>, Oct [6] J. Lang (ed.), Link Management Protocol (LMP), Internet-draft <draft-ietf-ccamp-lmp-10.txt>, Oct Kohei Shiomoto Senior Research Engineer, NTT Network Service Systems Laboratories. He received the B.S., M.S., and Ph.D. degrees in information and computer science from Osaka University, Osaka in 1987, 1989, and 1998, respectively. He joined NTT, Musashino, Japan in April 1989 and engaged in R&D of ATM traffic control and ATM ing system architecture design. From Augus996 to September 1997, he was engaged in research on high-speed networking as a Visiting Scholar at Washington University in St. Louis, MO, USA. From September 1997 to June 2001, he was directing architecture design for the high-speed IP/MPLS label router research project att Network Service Systems Laboratories, Musashino, Japan. From July 2001 to March 2004, he was engaged in research on photonic IP router design, routing algorithms, and GMPLS routing and signaling standardization att Network Innovation Laboratories. Since April 2004, he has been engaged in R&D of IP+optical att Network Service Systems Laboratories. He is a member of the Institute of Electronics, Information and Communication Engineers (IEICE), IEEE, and the Association for Computing Machinery. He is the Secretary of International Affairs of the Communications Society of IEICE. He was involved in the organization of several international conferences including HPSR 2002, WTC 2002, HPSR 2004, and WTC He received the Young Engineer Award from IEICE in NTT Technical Review