TDC365-2-subnets.pdf - TDC 365 Network Interconnection Technologies IP Subnets Greg Brewster DePaul University Topics Review IP Addresses DNS and DHCP

TDC365-2-subnets.pdf - TDC 365 Network Interconnection...

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TDC 365 Network Interconnection Technologies IP Subnets Greg Brewster DePaul University
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Review: IP Addresses DNS and DHCP Using IP Subnets Subnetting Straight Subnetting breaks address block into equal-sized subnets. Variable Length Subnet Masks (VLSM) breaks address block into variably-sized subnets Topics TDC 365 Greg Brewster, DePaul University 2
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Packet Headers and Addresses Web Server Browser GET DEFAULT.HTM Ethernet Trailer Ethernet Header IP Header Header TCP Src Port = 52531 Dest. Port = 80 Src IP = 140.192.35.12 Dest. IP = 140.192.81.6 IP: 140.192.81.6 MAC: 00:8a:22:53:9e:f2 IP: 140.192.35.12 MAC: 00:13:67:2b:de:a2 (O.S. assigns port #52531 to this browser process) In Response packet, Src and Dest values will be swapped in IP and TCP headers HTTP Request Src MAC = 00:13:67:2b:de:a2 Dest. MAC = 00:8a:22:53:9e:f2 TDC 365 Greg Brewster, DePaul University 3
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IPv4 Header IPv4 adds 20 bytes of IPv4 Header to every data packet These 20 bytes include all information required by IP routers to direct this packet to its destination. TDC 365 Greg Brewster, DePaul University 4
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IPv4 Header TDC 365 Greg Brewster, DePaul University 5
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IPv4 Header Fields Version : IP protocol version. Value = “4” for IPv4 header. IP Header Length : Length of IP header in 32-bit words Type of Service : Indicates whether this packet should be low or high priority Total Length : Length of IP packet in bytes TDC 365 Greg Brewster, DePaul University 6
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IP Header Fields Identification / Fragment Offset : used to identify and reassemble fragments that are formed when routers break IP packets into smaller packets Time to Live : Max. number of routers this IP packet may pass through. If exceeded, packet will be discarded. Protocol : Identifies the protocol carried inside the next header after this IPv4 header typically TCP or UDP. TDC 365 Greg Brewster, DePaul University 7
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IP Header Fields Header Checksum : Allows error checking of IP packets Source Address : 4-byte IPv4 source address for this packet Destination Address : 4-byte IPv4 destination address for this packet TDC 365 Greg Brewster, DePaul University 8
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