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Fall 2008 CMSC 150 1
Internetworking
Fall 2008 CMSC 150 2
Assumptions
• Data pipe from every machine to every other
machine.
– Need not be single link (and in most cases will
involve several links and several networks).
– Pipe can lose or corrupt messages (think postal
system analogy – vast majority of time it arrives, but
not always).
• So what info do we need to build a single
“logical” network (either reliable or
unreliable)?
Fall 2008 CMSC 150 3
Issues
• Getting various technologies to work with one
another (I.e. creating a single “network” from
many heterogeneous systems).
– Problem magnified since packet may need to
traverse several different networks (and network
technologies), each with their own addressing
schemes, service models, media access protocols,
etc.
• Scale: It’s the big issue
– How can you find an efficient path through a network
with millions (and perhaps billions eventually) of
nodes?
– How do you provide addressing for a network with
this many nodes?
Fall 2008 CMSC 150 4
Our Path
• The Internet Protocol (IP) Version 4
• Routing
• IPv6
• Multicast The present set of slides.
Fall 2008 CMSC 150 5
Internetwork:
• Arbitrary collection of possibly heterogeneous
networks interconnected to provide host-to-
host packet delivery service.
• Network: Directly connected or switched
network that uses a single technology (i.e.
ATM, 802.5, Ethernet).
– Could be many physical networks creating a single
logical network.
– E.g. several Ethernet networks connected on a
university campus
Fall 2008 CMSC 150 6
Internetwork
• Internet—THE internetwork.
– Runs the Internet Protocol (Kahn-Cerf)
– Interesting because it has faced the problems of
scale
• internet—abstract internetwork
