Johan J. Lukkien, [e-mail]

1
Computer Networks2002/2003

• Network Architecture
• Johan Lukkien

2
Network Architecture

• Elements
• Nodes (hosts)
• Interconnect (wires repeaters/hubs)
• Topology
• Software
• stack

3
Network architecture design

• Generality do not limit the scope unnecessarily
• avoid use-specific designs
• Robustness
• node link failure local impact
• limit effect of malfunctioning
• e.g. domains
• stability left to itself the system converges to
  a defined useful state
• e.g. no global reboots
• removing malfunctioning component is enough
• fault resilience
• detection auto-diagnose
• Byzantine behavior

4
Network architecture design

• Scalability
• design works for small and large networks
• e.g., performance, exploitation of locality
• extensions possible
• Configurability
• automatic (cf. stability), local configuration
• tweakable optimizable for certain conditions
• Determinism
• Migration evolution

5
Architecture and distance
home networks
wireless networks
long-distance wire-less
6
Local area networks

• Typically, based on shared medium
• broadcasting at layer 1 or layer 2
• Relatively small distance (few kilometers, at
  most)
• Simple topologies
• 10Base2 ethernet
• Star 10(0)BaseT
• Token ring
• ownership (token) passed around
• owner puts packets on an removes them from the
  ring
• owner puts token on the ring again
• medium can be shared as well
• as point-2-point

7
Local Area Networks

• High total bandwidth (the shared medium is fast)
• Limited number of nodes
• Low delay and error rate
• Broadcast facility supported
• i.e., part of the layer 2 service
• All nodes equal
• though some a bit more than others....

8
Standardizing LANs IEEE 802

• Working Groups and Study Groups
• 802.1 Higher Layer LAN Protocols Working Group
• Try to unify some issues for all LANs
  management, addressing, bridges
• 802.2 Logical Link Control working Group
• Issues in connecting to the network layer
• 802.3 Ethernet Working Group
• 802.4 Token bus Working Group
• 802.5 Token ring Working Group
• 802.11 Wireless LAN Working Group
• 11a, 11b, 11e, 11g
• 802.15 Wireless Personal Area Network (WPAN)
  Working Group
• e.g. BlueTooth, ...
• 802.16 Broadband Wireless Access Working Group
• wireless MAN
• 802.17 Resilient Packet Ring Working Group
• 802.18 Radio Regulatory TAG
• 802.19 Coexistence TAG
• 802.20 Mobile Broadband Wireless Access (MBWA)
  Working Group
• Link Security Executive Committee Study Group   

9
Metropolitan Area Networks

• Three components
• the access network for end-users
• at the end-user you may find a LAN again...
• connect to long-haul access points
• specifically serve enterprises
• e.g. file storage, disparate locations
• Requirements
• diverse access technology
• xDSL, cable, telephony, fiber
• diverse managerial domains
• home/enterprise equipment, PTT, cable company,
  leased lines
• locally fast, reliable and fair
• similar technologies as LAN, if possible

10
MANs examples

• Regular, special purpose networks
• cable TV just broadcasting and multiplexing of
  signals across the same physical medium
• telephony full duplex, point to point,
  connection oriented
• electricity
• General data communication
• re-use existing infrastructure

11
Cable and telephony

• Cable
• need to add two-way communication
• sharing of cable segments
• Telephone
• low bandwidth UTP

12
Wide Area Networks

• Long-range geographical distribution
• Separation of local net and subnet
• different management
• subnet just transport wires, switches, routers
  (no hosts!)
• Path-oriented transport through the subnet
• Note subnet
• properties will
• affect WAN
• services

13
Routing (path oriented)
14
Internetworks

• Connecting distinct networks
• add a subnet WAN
• connect using multi-ported devices in an existing
  network
• e.g. WAN-connected LANs
• No clear terminology for Internetworks but
• must have different technologies
• and different managerial domains
• Note
• technical distinctions (WAN, LAN, MAN...) are
  vanishing
• managerial distinctions are most relevant

15
Wireless

• Bandwidth sharing in cells
• Two modes
• point-to-point
• base-station (star)
• Overlap issues
• Three distance scales
• Wire-replacement
• LAN technology
• WAN technology

16
Wireless (cntd)

• Wire-replacement
• relatively low bandwidth main focus on system
  interconnect (BlueTooth, wireless USB) P2P
• cells roughly 10m
• LAN technology
• include link layer technology
• high bandwidth (i.e., only a factor of 10-100
  slower than wired) e.g. HiperLan, IEEE 802.11
  (WiFi)
• cells up to 100m
• P2P or base-stations
• WAN technology
• use long-haul connections, e.g. GSM, GPRS, UMTS
• cells up to 3 km
• base-stations

17
Home networks

• Special requirements
• diverse hardware and interconnect
• Information, Communication, Entertainment,
  Control
• must work, reliable, foolproof
• low cost
• much streaming, rather than bursty traffic
• high capacity
• does not work well with ethernet
• evolutionary path
• equipment is there for years to stay
• safe, secure, privacy protection

18
Connecting everything the Internet
19
Exercises

• Exercise 38 on page 84