Part 1 Flashcards
Same-layer interaction
2 PCs who use a protocol to communicate on the same layer
Adjacent-layer interaction
On a single PC. One layer provides a service to a higher layer, depending on what the software or hardware at the higher layer asked for.
Segment
Transport layer
Packet
Network layer
Frame
Link layer
OSI Layering benefits
- Less Complex
- Standard interfaces
- Easier to learn
- Easier to develop
- Multivvendor interoperability
- Modular engineering
10BASE-T and 100BASE-T Pin Pairs Used - Transmits on 1,2
PC NICs, Routers, Wireless AP
10BASE-T and 100BASE-T Pin Pairs Used - Transmits on 3,6
Hubs & Switches
Crossover cable
If the endpoints transmit on the same pin pair (Hubs & Switches)
Straight through cable
If the endpoints transmit on different pin pairs (PC NICs, Routers, Wireless AP)
MAC addresses
Media Access Control addresses are 6-byte-long (48-bit-long) binary numbes, most list as 12 digit hexadecimal numbers.
Before a product can have an ethernet port it must ask the IEEE to assign them a universally unique 3 byte code. (OUI)
Mac addresses consist of 2 parts, one from OUI and one vendor assigned
MAC represent
MAC represent a single NIC or ethernet port. These addresses are often called a unicast ethernet address.
MAC address issues
MAC works well providing its unique, because if someone has a the same there will obv be confusion
If two have same address, ethernet will solve this using an admin process
Half-duplex
Device must wait to send if receiving as frame, cant send and receive at same time
Full duplex
Can send and receive at the same time
IP Addresses and routers
All IP addresses in the same group must not be separated from each other by a router
IP addresses separated from each other by a router must be in different groups
Class A IP address - Networks and HPN
Networks: 126
Hosts per network: 16,777,214
Class B IP address - Networks and HPN
Networks: 16,384
Hosts per network: 65,534
Class C IP address - Networks and HPN
Networks: 2,097,152
Hosts per network: 254
Routing protocol goals
- Dynamically learn and fill routing table with a route to each subnet in the internetwork
- If more than one route available, choose the best one
- Notice and remove non valid routes
- If a route is removed, and another is available through another router, add this route to table
- To work quick when adding new routes or replacing lost routes
- Prevent routing loops
Basic DNS Name Resolution Request
- Click a page (e.g google.com)
- Connects to DNS server to find IP of google.com
- Returns the IP of google.com to host
ARP
- Discovers MAC addresses and caches them
- IP packets have IP address but not the physical address
- Sends out “If t his is your iP address please reply with your MAC address”
TCP/IP Transport Layer Features - Multiplexing using ports
Function that allows receiving hosts to choose the correct application for which the data is destined, based on the port number
TCP/IP Transport Layer Features - Error recovery (reliability)
Numbering and acknowledging data with sequence and acknowledgement header fields
