Computing – Communications and Networks - 12-Internet protocol stack

Internet protocol stack

 Application: supporting network applications
 FTP, SMTP, HTTP, OSPF, RIP
 Transport: host-host data transfer
 TCP, UDP
 Network: routing of datagrams from source to destination
 IP
 Link: data transfer between neighboring network elements
 PPP, Ethernet
 Physical: bits “on the wire”

Protocol layering and data


Each layer takes data from above
 adds header information to create new data unit
 passes new data unit to layer below

OSI ISO Model



Application              Common functions
Presentation             Interchangable formats
Session                    Organizing dialog
Transport                 Reliable transmission
Network                  Forwarding in the network
Data link                  Transmission between two nodes
Physical                   Signal transmission


ATM protocol stack
 Application: native applications, other protocols
 LAN Emulation, IP, Signaling
 Transport: host-host data transfer
 SSCOP
 Adaptation: adapt the ATM layer to different types of applications
 circuit emulation, real-time data
 AAL5 suitable for IP traffic
 ATM: cell switching over virtual circuits
 Physical: bits “on the wire”, usually fiber


LAN stack
 Management: e.g. construct forwarding tables
 SNAP: Spanning Tree protocol
 LLC: multiplex different protocols
 IP, IPX, SNAP
 MAC: medium access
 802.3 (Ethernet), 802.4 (Token Ring), 802.5 (Token Bus), 802.11 (Wi-Fi)
 Physical: bits “on the wire”

Interconnection at layer
 Switches (bridges)
 interconnect hosts
 logically separate groups of hosts (VLANs)
 managed by one entity
 Type of the network
 broadcast
 Forwarding based on MAC address
 flat address space
 forwarding tables: one entry per host
 works if no loops
 careful management
 Spanning Tree protocol
 not scalable