Ports are used by TCP and UDP to identify the next layer up in the packet.
IP has a Protocol field that has a similar function.
Ethernet II has EtherType. IEEE 802.3 has the 802.2 Service Access Point
(SAP). IPX and AppleTalk have sockets.
Almost every protocol has some way of specifying what the next layer up is.
The recipient uses it to pass the data to the right process. The sender
also uses it to identify itself.
Socket has another meaning in the Unix world which I have never quite
understood. Perhaps someone else can explain that.
Priscilla
At 08:25 PM 9/12/01, Dennis Laganiere wrote:
>Hopefully this will start a new conversation. I've tried to describe the
>difference between Ports and Sockets. Your thoughts are welcome...
>
>Port Numbers are used by IP to pass information to the upper layers; they
>provide the mechanism for cooperating applications to communicate. Numbers
>below 1024 are well known ports, and above 1024 are dynamically assigned
>ports. You will usually find registered ports are for vendor specific
>applications in the range above 1024.
>
>Here are some common IP Ports:
>20/21 FTP
>23 Telnet
>25 SMTP
>37 Time Service
>49 TACACS
>53 DNS
>67 BootP Server
>68 BootP Client
>69 TFTP
>110 POP3
>161 SNMP
>
>IPX sockets are part of the IPX stack, and are used much like port numbers
>in IP; they direct data encapsulation in the IPX Header to the appropriate
>upper layer protocols. There are well-known ones, others that are assigned
>to proprietary applications, and a series of numbers used randomly by
>clients, just like in IP. Also like IP ports, they identify the process on
>the server or client that needs to get the data in the packet.
>
> Here are some common IPX sockets:
> 0x451 NCP
> 0x452 SAP
> 0x453 RIP
> 0x455 NetBios
> 0x456 Diagnostic
> 0x457 Serialization
> 0x85be IPX EIGRP
> 0x9001 NLSP
> 0x9004 IPXWAN
> 0x9086 IPX Ping
>
>
>The AppleTalk protocol suite also uses sockets. Socket numbers 1-127 are
>statically assigned (RTMP uses 1, ZIP uses 6, etc).
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=19704&t=19701
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