Every ethernet interface has a 6 byte address stored

Every Ethernet interface has a 6-byte address stored
in the interface hardware called:
o physical address
o MAC (medium access control) address
o Data-link address
• Set by manufacturer – a serial number
• Values written in hexadecimal notation.
• Example: 18-5E-0F-0A-38-2D
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Device addresses
• Address information (both MAC and IP) for a network
connection can be found Network details or by running
“ipconfig /all” (“ifconfig” on Mac).
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What happens when we “mail” a
request and get a response
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Example: Web Request
Web Server
Browser
Src Port = 52531
Dest. Port = 80
Src IP = 140.192.35.12
Dest. IP = 140.192.81.6
IP: 140.192.81.6
Phy: 00:B9:72:32:11:AD
IP: 140.192.35.12
Phy: 00:A1:B2:33:44:DD
(O.S. assigns port
#52531 to this
browser process)
In Response packet,
Src and Dest values will be
swapped in Ethernet, IP
and TCP headers
HTTP Request
Src Phy = 00:A1:B2:33:44:DD
Dst. Phy = 00:B9:72:32:11:AD
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Relationship of layers and addresses in TCP/IP
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Ethernet
Most common LAN type
Ethernet
• Most widely used LAN technology
• Operates in the data link layer and the physical layer
• Family of networking technologies that are defined in the
IEEE 802.2 and 802.3 standards
• Supports data bandwidths of 10, 100, 1000, 10,000,
40,000, and 100,000 Mbps (100 Gbps)
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Ethernet Protocols
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Wired Ethernet LAN
• A group of devices connected into Ethernet hubs or
switches.
• Each LAN device has a wired Ethernet interface called a
LAN Port or Network Interface Card (NIC) or adapter.
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GOLDMAN: LAN
FIG. 01-05
Network Interface
Card (NIC) Networking
Software
(NS)
NIC
NS
NIC
NS
NIC
NS
NIC
NIC
NS
NIC
NS
NIC
NS
The Network Interface Card (NIC)
and Networking Software (NS) must
be compatible with each other and
with the computer or device into
which they are installed.
Network Hub or
Wiring Center
Shared Laser
Printer
Shared
Application
Server
Media
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Ethernet MAC addresses
• Every Ethernet interface (NIC) has a 6‐byte physical
address or MAC (medium access control) address
assigned and burned into the interface hardware when it
is manufactured.
• MAC address is like a serial number.
• MAC address of every Ethernet device is guaranteed to be
globally unique.
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MAC Address: Ethernet Identity
• Layer 2 Ethernet MAC address is a 48‐bit binary value
expressed as 12 hexadecimal digits.
• IEEE requires vendor to follow 2 simple rules:
• Must use vendor's assigned OUI as first 3 bytes.
• All MAC addresses with the same OUI must be assigned a unique value in last 3
bytes.
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MAC Address Representations
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They have three main “classes” of
recipients
When Hosts talk in a Subnet
Unicast MAC Address
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Broadcast MAC Address
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Multicast MAC Address
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GOOD NIGHT, SEE YOU NEXT WEEK

Questions?

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