-Internet is the progeny of the research project of US DoD called Arpanet.
-today's Internet is a collection of private networks that meet at 'peering points'.
-tcp/ip is the networking system that underlies the Internet.
-the technological success of the Internet is largely due to
. the elegant and flexible design of tcp/ip
. the fact that tcp/ip is an open and non-propreitary protocol suite.
-the governance of the Internet is largely open and vague except three main players:
. icann - takes care of addressing; operates under an mou from US Dept of Commerce.
. isoc - takes care of engineering aspects; superset of ietf.
. igf - takes care of intergovermental operations. setup recently in 2005 by UN.
-the technical activities of the Internet are summarized in docs called RFCs or request for comments.
-RFCs are maintained by ietf.
-there are about 5600 RFCs.
-tcp/ip is a protocol suite comprising 5 protocols:
. ip - responsible for routing packets
. icmp - responsible for low level debug and error assistance to ip.
. arp - responsible for converting ip addr to h/w addr
. udp - responsible for unverified one way data delivery
. tcp - responsible for reliable, full duplex communication.
-tcp/ip has 5 layers:
. physical
. link
. network
. transport
. application
<<< plnta like polenta >>
-tcp/ip version 4 or simply ipv4 is a 4 byte addressing scheme that has been prevalent for over 3 decades.
-ipv4 is end of life as it ran out of addresses in 2011.
-tcp/ip version 6 or simply ipv6 is an ipv4 replacement.
-ipv6 uses 16 bytes of addresses. mainstream ipv6 adoption is likely to take a few years still.
-ipv6 is a superset of ipv4. it adds a few changes in concepts and notation--but thats about it.
-tcp/ip allows compatible hardware and networks to talk to each other.
-tcp/ip data unit is called as:
. frame in the link layer
. packet in the ip layer and
. segment in the transport layer
-but the most common name is packet.
-each packet contains:
. a header - source destn info + checksum
. a payload - the actual data
-as a packet travels across the 5 layers of tcp/ip, each layer adds its own info to the packet header.
-this process is called encapsulation.
-the size limit of a frame is associated with the link layer and is called Max Transfer Unit (MTU).
-the payload of a standard ethernet frame is usually 1500 bytes.
-in other words, the MTU for ethernet is 1500 bytes.
-if the packet has to pass through differnt networks of different MTUs, then the router can subdivide the packets.
-this process is called fragmentation and it increases router workload.
-ipv6 has mechanisms to avoid this by making the originating host to do the work itself.
-to do so ipv6 allows the intervening small mtu network to notify the originating host by an icmp error.
-the originating host then re-sends the packets that fit the smallest mtu of the network.
Next up, tcp/ip networkings ...
-today's Internet is a collection of private networks that meet at 'peering points'.
-tcp/ip is the networking system that underlies the Internet.
-the technological success of the Internet is largely due to
. the elegant and flexible design of tcp/ip
. the fact that tcp/ip is an open and non-propreitary protocol suite.
-the governance of the Internet is largely open and vague except three main players:
. icann - takes care of addressing; operates under an mou from US Dept of Commerce.
. isoc - takes care of engineering aspects; superset of ietf.
. igf - takes care of intergovermental operations. setup recently in 2005 by UN.
-the technical activities of the Internet are summarized in docs called RFCs or request for comments.
-RFCs are maintained by ietf.
-there are about 5600 RFCs.
-tcp/ip is a protocol suite comprising 5 protocols:
. ip - responsible for routing packets
. icmp - responsible for low level debug and error assistance to ip.
. arp - responsible for converting ip addr to h/w addr
. udp - responsible for unverified one way data delivery
. tcp - responsible for reliable, full duplex communication.
-tcp/ip has 5 layers:
. physical
. link
. network
. transport
. application
<<< plnta like polenta >>
-tcp/ip version 4 or simply ipv4 is a 4 byte addressing scheme that has been prevalent for over 3 decades.
-ipv4 is end of life as it ran out of addresses in 2011.
-tcp/ip version 6 or simply ipv6 is an ipv4 replacement.
-ipv6 uses 16 bytes of addresses. mainstream ipv6 adoption is likely to take a few years still.
-ipv6 is a superset of ipv4. it adds a few changes in concepts and notation--but thats about it.
-tcp/ip allows compatible hardware and networks to talk to each other.
-tcp/ip data unit is called as:
. frame in the link layer
. packet in the ip layer and
. segment in the transport layer
-but the most common name is packet.
-each packet contains:
. a header - source destn info + checksum
. a payload - the actual data
-as a packet travels across the 5 layers of tcp/ip, each layer adds its own info to the packet header.
-this process is called encapsulation.
-the size limit of a frame is associated with the link layer and is called Max Transfer Unit (MTU).
-the payload of a standard ethernet frame is usually 1500 bytes.
-in other words, the MTU for ethernet is 1500 bytes.
-if the packet has to pass through differnt networks of different MTUs, then the router can subdivide the packets.
-this process is called fragmentation and it increases router workload.
-ipv6 has mechanisms to avoid this by making the originating host to do the work itself.
-to do so ipv6 allows the intervening small mtu network to notify the originating host by an icmp error.
-the originating host then re-sends the packets that fit the smallest mtu of the network.
Next up, tcp/ip networkings ...
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