IP over networks

1
IP over networks

• Heikki Almay
• Kari Melkko
• Risto Mononen
• IP seminar 28.9.1998

2
IP in the backbone

• 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

3
Eg. Cisco 12000 Series

• Quotes from http//www.cisco.com/warp/public/733/1
  2000/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
Multiprotocol over FR

• 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

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 gt 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