CSC 412 - Networking Scott Heggen. Agenda Finish 4 + 1 TCP – Part 1.
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Transcript of CSC 412 - Networking Scott Heggen. Agenda Finish 4 + 1 TCP – Part 1.
Let’s Review
• What does the network layer do?
• What does the data link layer do?
• What does the physical layer do?
SW1
DataEthernet, Source:0010.1111.1111, Destination:0030.3333.3333
MAC Address TablePort MAC 1 0010.1111.1111 9 0030.3333.3333
R1
DataIP, Source:8.1.1.1, Destination:130.4.3.3
R1(config)# ip route 130.4.0.0 255.255.0.0 200.55.99.251
IP Routing TableDest. Next-Hop130.4.0.0 200.55.99.251
. .
. .
R2
DataIP, Source:8.1.1.1, Destination:130.4.3.3
IP Routing TableDest. Next-Hop130.4.0.0 100.55.99.251
. .
. .
SW2
DataEthernet, Source:0050.5555.5556, Destination:0020.2222.2222
MAC Address TablePort MAC 1 0050.5555.5556 9 0020.2222.2222
Reflecting on this process so far…
• Do any of the bottom three layers handle error correction?• Do any of the bottom three layers handle in-order delivery?• Do any of the bottom three layers handle delivery of data to the correct
device?• Do any of the bottom three layers handle delivery of data to the correct
process within the device?• Do any of the bottom three layers handle controlling the flow of data
(slowing down/speeding up data transfer rate??)• Do any of the bottom three layers handle breaking up data into smaller
segments?
Transport Layer
• The transport layer does all of those things (except delivery of data to the correct device; that was network layer (remember routing?!!?))• Flow control (using windowing)• In-order delivery (reassembling segments into the correct order)• Error recovery (lower layers handled error detection only; transport actually
fixes it!)• Segmentation (other layers do break the message into smaller chunks, but
transport layer does it better)• Identifies applications within a device via port numbers