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IP over networks

Explore the evolution of IP networking protocols over various link layers, including LAPF, AAL5, and PPP in technologies like PDH, SDH, and WDM. Discover how routers and interfaces support high-speed backbones with Gigabit Switch Routers and advanced encapsulation methods. Uncover the intricacies of IP over SONET/SDH, ATM, Frame Relay, and Ethernet, along with the transition to MPLS technology for scalable and efficient IP forwarding. Learn about industry suggestions, such as IFMP, CSR, and IP switching mechanisms like RSVP and Tag Switching, and delve into research projects like CBQ and RED gateways for enhancing network performance.

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IP over networks

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  1. IP over networks Heikki Almay Kari Melkko Risto Mononen IP seminar 28.9.1998

  2. “IP over anything” rule guarantees the connectivity Link-layer specific encapsulation and possibly connection setup needed Common link-layers: LAPF, AAL5, PPP PDH, SDH or WDM transmission path in the bottom Routers have several IP interfaces with possibly different physical media IP in the backbone

  3. Eg. Cisco 12000 Series • Quotes from http://www.cisco.com/warp/public/733/12000/gsrfs_ds.htm: • The Gigabit Switch Router (GSR) delivers scalable IP forwarding and services performance in a carrier-class platform, enabling high-speed IP backbones to scale to OC-3 (155 Mbps), OC-12 (622 Mbps), and OC-48 (2.4 Gbps) facilities. • Supports a combination of IP over SONET/SDH and ATM interfaces, including other high-speed media: • Four-port OC-3/STM-1 IP over SONET/SDH • One-port OC-12/STM-4 IP over SONET/SDH • One-port OC-12/STM-4 ATM • Future line cards, including: • Four-port OC-3/STM-1 ATM • Four-port OC-12/STM-4 IP over SONET/SDH • One-port OC-48/STM-16 IP over SONET/SDH • Gigabit Ethernet

  4. Frame Relay • Variable size frames over PCM links • LAPF / HDLC framing • "Streamlined X.25 / LAPB": • outband signalling • layer 2 multiplexing • end-to-end flow and error control above LAPF • hop-by-hop FCS checking to drop corrupted frames • Application Application • TCP/IP TCP/IP • LAPF - - - - - - - - - - LAPF - - - - - - - - - - - - LAPF • PHY PHY PHY • End node Switching node End node

  5. Routing mode need layer 3 NLPID IP NLPID is 0xCC save 48 bits over bridging Bridging mode encapsulate whole MAC frame NLPID 0x80 + SNAP define (LAN) protocol FR level fragmenting Complicated ARP Usually DLCI has only local significance Frame Relay network provides a method for obtaining the correct DLCIs Encapsulated IP packet: flag 0x7E Q.922 address (DLCI) Control 0x03 NLPID 0xCC IP Datagram FCS flag 0x7E Multiprotocol over FR

  6. IP over ATM • “IP over ATM: A Framework Document" [RFC1932] • LLC/SNAP encapsulation is default • CLIP and LANE • TULIP strips IP header • need end-to-end ATM • TUNIC strips layer 4 header • replace TCP port based multiplexing with VC multiplexing • "Multiprotocol Encapsulation over ATM Adaptation Layer 5" [RFC1483] • MPLS work lead to new draft 1998 • Working technology in single LIS (IP subnet) • Routing between LISes ongoing work

  7. IP over SONET/SDH and WDM • ANSI and ITU-T flavors of synchronous links • "PPP over SONET/SDH" [RFC1619] • octet synchronous HDLC encapsulation • add scrambling 1998 • scales up to OC-48/STM-16/2.5 Gb/s • WDM will provide huge bandwidth > OC-48 • Lucent's Simplified Data Link (SDL) delineation proposal • variable length frames • header CRC • payload CRC • hunt for SONET H4 byte (?) and/or correct header CRC • add QoS and multiplexing to get “ATM lite”

  8. IP switching • Industry suggestions • data driven • Ipsilon Flow Management Protocol (IFMP), Cell Switch Router (CSR) • snoop packets to find a flow • control (topology) driven • Tag Switching, Aggregate Route-Based IP Switching (ARIS), IP Navigator • routing updates and RSVP messages trigger VC setup • ATM Forum: MPOA/NHRP • IETF: RSVP, MPLS • Traditional Internet: connectionless datagram forwarding • (IP) Switching is always connection oriented and needs signalling: RSVP, LDP, SS7, PNNI, … • Internet wants all the switching goodies with new names

  9. DiffServ • Last pure stateless attempt? • Take IP header TOS bits in use • Priority queuing enhances QoS • Still best-effort inside each “class” • CAC or pricing to protect backbone? • Interoperate with RSVP in enterprise net and ATM in backbone • Van Jakobson's research http://www-nrg.ee.lbl.gov/ • Research projects with their own web pages include: • CBQ (Class-Based Queueing, including link-sharing); • ECN (Explicit Congestion Notification); • RED gateways (Random Early Detection Gateways); • SRM (Scalable Reliable Multicast); • the VINT project, based on the UCB/LBNL Network Simulator ns ( ns-1, ns-2) • Adaptive Web Caching ;

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