EP005

Shownotes: Networking part 2; Networking networks

Envelopes inside of envelopes, or layers on a wedding cake
How to reach out from one network to another?
late 60s DARPA (Defense Advanced Research Projects Agency) put on problem. Resilience in consideration if one spot bombed out. arpaNet project started flourishing in the mid 70s. What did they figure out?
late 70s was spent linking universities together, validating ARPANET over the TCP/IP protocol
my mid 80s TCP/IP was accepted as the common protocol for linking universities together.
TCP/IP is the protocol suite, made up or IP that everything rides over, then TCP, UDP and ICMP as higher messages that ride in IP packet envelope
One LAN – Router at one site – Router at other site – other LAN
Other important IP (v4 and V6 common) features (already covered version, source and destination addresses)
Protocol
Time to live
fragmentation flag and offset
length and payload

IP address, subnet/netmask, broadcast, default gateway

ICMP (Internet Control Messaging Protocol): ping (request / reply) combined with TTL to make traceroute
Super useful for routers with sub protocols (time stamp, source quench, etc)

UDP (User Datagram Protocol):
stateless, 1 way message
good at lossy communications
smarts got to be built into higher applications
important header bits: Source port, destination port
What downsides exist with one way stateless protocols?

TCP (transmission Control Protocol):
still does source port destination port
statefull
flags used for control bits
sequence of datagrams tracked with syn & ack

privacy
integrity
availabiity

URL

Important application protocols for internetworking
DNS
DHCP
NTP

References:
IP stack and history
ICMP
UDP
TCP
URL
DNS
IPv4
IPv6
2128

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