CCNA/CCNP preparation notes

by Andreas Ryf
OSI reference model
1: Physical Layer
2: Data Link Layer
3: Network Layer
4: Transport Layer
5: Session Layer
6: Presentation L.
7: Application Layer
IP Network Classes
Subnetting
Cables & fibres
Terms
Links
BCMSN
ONT

Layer 3: Network layer

 

IP, IPX/SPX, Appletalk, OSI

 

IP addresses, routing, limit of Ethernet-broadcast domains, no acknowledge of reception, no delivery guarantee.

mapping of IP addresses to Ethernet adresses and vice versa by ARP and RARP.

 

Packets, fragmentation

 

TTL, time to live, packets have limited life expectancy to limit negative effects of routing loops.


 

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