15 TCP header details (I) source, destination port: 16,16 - identify applications at ends of the connection sequence :32 - indicates 1st data octet in this segment acknowledgment :32 - next expected sequence number, valid only when the ACK bit (reside in flag) is set
16 TCP header details (II) data offset :4 - 32 bit words offset tells the receiver where user data begins reserved :6 -not used flag :6 URG : validity of urgent pointer field ACK : validity of acknowledge field PSH : push request (pass segment to appl layer immediately) RST : reset the connection SYN : initial synchronization FIN : sender at end of byte stream
17 TCP header details (III) window :16 - advertise amount of buffer space this node has allocated checksum :16 - 16 bits 1 ’ s complement of pseudo header, TCP header and data urgent pointer :16 - byte position of data that should be processed first options - variable length option e.g. MSS (max segment size) tells destination node
38 Broadcast Addresses Layer 2 broadcasts These are sent to all nodes on a LAN. Broadcasts (layer 3 ) These are sent to all nodes on the network. Unicast These are sent to a single destination host. Multicast These are packets sent from a single source, and transmitted to many devices on different networks.
39 Layer 2 broadcasts known as hardware broadcasts they only go out on a LAN The broadcast would be all 1s in binary and all Fs in hexadecimal, as in FF.FF.FF.FF.FF.FF.
40 Broadcasts (layer 3 ) Broadcast messages are meant to reach all hosts on a broadcast domain. example that you’re already familiar with: The network address of 172.16.0.0 255.255.0.0 would have a broadcast address of 172.16.255.255 Broadcasts can also be “all networks and all hosts,” as indicated by 255.255.255.255. A good example of a broadcast message is an Address Resolution Protocol (ARP) request.
68 Types of IPv6 Addresses Unicast single host/one to one (Global, Site-local, Link local) Multicast multiple host in specified range/one to many Anycast multiple host, only received by single host (the nearest host) /one to nearest (unicast) No Broadcast use Mulicast Efficient use of the network Range can be much larger
69 Address type identification Unspecified 00..0 ::/128 Loopback 00..1 ::1/128 Link Local 1111 1110 10 FE80::/10 Multicast 1111 1111 FF00::/8 All address types have to support EUI- 64 bits interface ID setting Except for multicast
71 IPv6 Address Allocation IANA allocated 2001::/16 to IPv6 Unicast RIR gets /23 prefixes from IANA RIR allocate /32 prefix to an ISP ISP allocate /48 prefix to end customer
72 IPv6 Interface IDs Lowest order 64-bit field ของ unicast address จะถูกกำหนดได้ด้วยหลายวิธีที่ แตกต่างกัน Auto-configured from a 64 bit EUI-64 Auto-generated random number DHCPv6 Manually configured
73 Converting 48-Bit MAC Addresses to IPv6 Modified EUI-64 Identifiers
76 The IPv6 header fields are as follows: version (4 bit): Indicates the protocol version, and will thus contain the number 6. DS byte (8 bit): This field is used by the source and routers to identify the packets belonging to the same traffic class and thus distinguish between packets with different priorities. flow label (20 bit): Label for a data flow payload length (16 bit): Indicates the length of the packet data field.
77 The IPv6 header fields are as follows: (2) next header (8 bit): ): Identifies the type of header immediately following the IPv6 header. hop limit (8 bit): Decremented by one by each node that forwards the packet. When the hop limit field reaches zero, the packet is discarded. source address (128 bit): The address of the originator of the packet. destination address ( 128 bit) : The address of the intended recipient of the packet. Reference->http://www.ietf.org/rfc/rfc2460.txt