CISC 370 - Class Today
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Structured Wiring
A wiring closet
Ethernet continued
Wiring exercise
ARP
DHCP
Lab
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R. Smith - University of St Thomas - Minnesota
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Structured Wiring
• Standard layout for multifloor buildings
– Horizontal cable, backbone (vertical cable), external cable
• Layout
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Wiring plugs attached to horizontal wiring
Horizontal wires collect in wiring closets on each floor
Vertical wire serves as ‘backbone’ to connect floors
Backbone connects on ground floor to external cable
3/15/2016
R. Smith - University of St Thomas - Minnesota
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Tour Time
• Back soon.
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R. Smith - University of St Thomas - Minnesota
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Routing Exercise
• Net Architecture
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Hosts A and B are on LAN 1
Hosts C and D are on LAN 2
Hosts E and F are on LAN 3
B and C are connected via L3 router
D and E are connected via firewall with NAT (E, F “inside”)
• Do these get through?
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Host A with MAC address for B; with MAC addr for C
Host A with Internet address for C; with Internet address for F
Host F with Internet address for A
Host F with MAC address for A; MAC address for C
• Add e-mail routing
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R. Smith - University of St Thomas - Minnesota
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Ethernet
• Classic and Fast Ethernet
– 10baseT, 100baseT
– “Bus” topology
– CSMA/CD access to the bus
• Gigabit Ethernet
– 1000baseT, 10Gbase-S, -L, -E (short, long, extended)
– Interconnected stars
– Switched access
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R. Smith - University of St Thomas - Minnesota
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Addressing on a LAN
• Address Resolution Protocol
• Mapping MAC to IP and back
– Requester wants to know a target’s MAC address (knows IP)
– Requester sends a ‘broadcast’
– Someone (usually the ‘target’) answers
• “Reverse ARP”
– Given a MAC address, get the IP address
– An early form of boot-up configuration
• Looking at ARP via Wireshark
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R. Smith - University of St Thomas - Minnesota
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DHCP
• Dynamic Host Configuration Protocol
– Also sometimes called ‘bootp’ (i.e. in Wireshark)
• Used when a host boots up
– The host sends a broadcast query
• Uses UDP (ports 67 & 68); client usually ID’d with its MAC addr
• Routable – relies on ‘forwarding agents’ in routers
– A DHCP server responds with initial IP configuration data
• Typical configuration data
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Host’s assigned IP address (may be temporary w/expiration)
Address of default gateway (router), and network mask
Address(es) of DNS server(s) to use
Other useful info (Windows server addresses)
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R. Smith - University of St Thomas - Minnesota
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The Lab
• Lab Objective: map the lab machines
• Lab Groups
– I’ve assigned groups via e-mail – I’ll also post groups
– Do the labs as a group (this one and future ones)
– If you want to trade group members, talk to me FIRST
• Where to do it
– Lab upstairs – OSS 428
• When to do it
– I’ll set up a schedule
3/15/2016
R. Smith - University of St Thomas - Minnesota
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Let’s visit the lab
• It’s upstairs
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R. Smith - University of St Thomas - Minnesota
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