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to settle an argument at work.
Is it possible, in theory, to create a network protocol with ports higher than 65535 and get it approved by IANA ?
if not, why not ?
Yes. It is possible to create one with an arbitrary number of ports.
Getting it approved by IANA (and IETF, ISO and whoever else are concerned) is just a matter of getting enough people to use your wonderful new invention. Which is extremely unlikely but not theoretically impossible.
If you are using TCP or UDP on top of IP, then no. Both TCP and UDP only use 16 bits for the port number. If you are using some other protocol suite such as IPX/SPX, then it depends on that protocol. If you are making your own protocol, then you can do whatever you want. Getting it approved by IANA is a different story.
http://en.wikipedia.org/wiki/Transmission_Control_Protocol
http://en.wikipedia.org/wiki/User_Datagram_Protocol
2^16 = 65536 different ports
Since computer numbers start counting at 0, this leaves 65535 as the max.
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When you configurate some interface for a device using 'ifconfig eth0 xxx.xxx.xxx.xxx up' what's the difference bettween using IP like '192.168.0.2' and '192.168.0.2/30'.
I understand the idea of a submask and that it's good use for redirect datagrams only taking part of the IP address but I dont get why using it when assinging the IP for some interface.
I found out that using the submask when for assigning the IP address establish the range for the broadcast direction.
So using direction like '192.168.0.2' will establish broadcast on '192.168.0.255' but using '192.168.0.2/30' will use '192.168.0.3' since its the last avaible direction when you taking the first 30 bits.
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I am working on a small embedded device based upon an STM32F4xx MCU. It implements a TCP/IP server over a Wi-Fi connection. The question I have relates to exposing the IP address of the device so that it may be discovered by computers on the same network. UPnP and SSDP seem to be rather "heavy" solutions to this problem.
Are there other techniques/protocols that have a smaller footprint than UPnP and SSDP?
Thanks in advance for your input,
Sid
If you can make up any custom protocol, a simple UDP beacon periodically sent to the broadcast address (255.255.255.255 or your preferred interface's broadcast address) is simple and reliable.
Synopsis of comments:
For listing in mainstream platforms' (Windows, Linux, OS X) network views, the best option would likely be to implement the full stack required for Windows' Network Discovery.
If hostname lookup is enough, Netbios or mDNS could be enough.
The search term you are likely looking for is zero-configuration networking and should give you all the available options
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I would like to create a new protocol, i.e having features of TCP and UDP. can you tell me what are tips and techniques are required if it is possible.
Thanks in advance
TCP gives you three features that UDP does not: (a) estimating sending rate, (b) retransmission, and (c) flow-control. In doing so, the tradefoff is that TCP becomes slower compared to UDP. So, if your application is delay sensitive, which is typically true for audio/video applications, then you need to start with UDP and keep whichever of the above three you want. Typically, UDP applications might add forward-error-correction or application layer packet-book-keeping to ensure retransmission.
There is yet another advantage that UDP offers which TCP does not: if you have an application that might use mulitcast. For such cases, UDP would be the right chioce since UDP can handle point to multipoint. Using TCP for multicast applications would be hard since now the sender would have to keep track of retransmissions/sending rate for multiple receivers.
So, in summary, UDP will offer you two features that TCP cannot: lower-delay and ability to do multicast. So, this way, we can actually reduce the scope of the question and ask what are the features of TCP that one would like to add to UDP since there is no way, one can add features of UDP to TCP.
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whats the purpose of local IP addresses if there are mac addresses? ARP maps mac addresses to IP addresses but I don't see why it's needed, because I thought data on LANs are sent as frames which only care about the mac addresses.
Long ago and far away, there was more to the world than Ethernet LANs, and application writers didn't care whether your PC was attached to an Ethernet, a Token Ring, an XNS net, or dial-up. IP provides a layer of abstraction and coherence across the top of all those and many more, allowing application authors to ignore the differences between them.
And what happens if you want to talk to a macine that isn't on your local area network (such as StackOverflow).
IP allows routing of packets anywhere, not just locally in your current network segment and, though it's mostly over Ethernet now, IP can equally well work over other underlying layers, giving a consistent view to the upper layers. This is vital given how much stuff is actually built on IP (DNS, FTP, SSH, HTTP and so on).
Machines almost certainly will cache IP-to-ethernet details to speed up subsequent transfers so the impact of translation on the LAN isn't so bad.
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MAC address are used for uniquely identifying my computer.
IP address are used for routing the packets to the network, as it has got a hierarchial structure, but it doesn't uniquely identifies a computer. So, after IPv6, each computer will have a unique IP address, so will there be any need of MAC address then?
Please do correct me, if I had understood something wrong.
No. MAC addresses operate at layer 2 ("data link layer"). The Internet Protocol (both IPv4 and IPv6) operates at layer 3 ("network layer").
These two layers are complimentary, and do not "replace" each other. For more information, read up on the TCP/IP suite.
IPv6 stateless address autoconfiguration (SLAAC) uses the MAC address to generate the address, but that does not mean they "replace" each other. It's simply a characteristic of the layer 2 interface being inherited by the layer 3 addressing. Other than that, completely complimentary.