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Trends in NetworksTrends in Networks• Networking Principles
• LANs: Gigabit Ethernet vs. ATM
• WAN: SONET/SDH
• QoS: Policy-Based Routing
• Middleware: Caching, Pricing, Load Balancing
• Multicasting: MBONE, Reliable
• Applications: Voice over IP
• Technology: ADSL, WDM, Switches
• Active Networks
• Security
Varaiya - WalrandUC Berkeley
4/1998
Trends in NetworksTrends in Networks• Networking Principles
• LANs: Gigabit Ethernet vs. ATM
• WAN: SONET/SDH
• QoS: Policy-Based Routing
• Middleware: Caching, Pricing, Load Balancing
• Multicasting: MBONE, Reliable
• Applications: Voice over IP
• Technology: ADSL, WDM, Switches
• Active Networks
• Security
Varaiya - WalrandUC Berkeley
4/1998
Networking PrinciplesNetworking Principles
• Driving Forces: Digital, Packets, Economies of Scale & Integration
• Internetworking: How do we connect different networks?
Algorithm: If ACKs are delayed, reduce window size; Else, increase.Note: Current algorithms are not very good. Could be improved with router measurements.
Networking PrinciplesNetworking Principles
End-to-End Principle: Religion or Science?
Principle: Don’t ask the network to do what hosts can do“Keep the network as simple as possible”
Motivation: Scalability: As more hosts are added, they can do more Upgradability: If most functions are in hosts, can upgrade Flexibility: Different hosts need different functions
Examples: Datagram Transmission in IP (no connection state in routers) Error/Flow/Congestion Control in TCP Compression, Encryption Soft-States (need to be refreshed) for multicast groups, RSVP
Networking PrinciplesNetworking Principles
End-to-End Principle: Religion or Science?
Limitations of End-to-End Principle:
Reservation of resources for QoS? Billing? Effective congestion control? Persistent connections for slow links?
Active networks may be a compromise?
LANs: Gigabit Ethernet vs. ATMLANs: Gigabit Ethernet vs. ATM
ATM
1
1
2
1
VCI
PVC or SVC
5+48 bytes
Gigabit Ethernet
a
b
c
d
a | d |
a | d |
b | d |
b | d |
MAC addresses
S&F or cut-through
640-1.5 kB
LANs: Gigabit Ethernet vs. ATMLANs: Gigabit Ethernet vs. ATM
A -> B: A -> V: P = [b|a|…] V -> S: b = ? S -> V: b on W V -> W: P / AAL5 W -> B: P
LAN Emulation
Applications/IP do not take direct advantage of QoS of ATM
A
B
C
V
W
D
Z LANEServer
S
LANEAALATM
MAC LANEAALATM
IPLANEAALATM
LANs: Gigabit Ethernet vs. ATMLANs: Gigabit Ethernet vs. ATM
Gigabit Ethernet ATM
Compatibility Yes With LANE
Setup Easy Define VCsQoS Coming YesCost Small MediumMAN Gigabit Mesh Router or