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IP over networks

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

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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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