Good day, I connected two computers together with an Ethernet straight-through cable. I did not configure any ip address, and after a while they both got APIPA addresses. Now they can ping each other and share files. I am a bit confused because firstly, it's a straight-through cable, so there should be no communication and secondly, when I type in "ipconfig /all" in cmd on both computers, there is no subnet mask. How is communication even possible? I am so confused.
APIPA Addresses – Communication Between Two Computers via Ethernet
cableethernetlayer1
Related Solutions
This can introduce a number of problems, like additional attenuation or cross talk. Splicing is to be avoided whenever possible, but I have seen this work in a pinch although I would never recommend it. They key is to use a cable certification tester (not just a continuity tester) to make sure it still passes your required standard (Cat5/5E/6) after splicing.
I would also be concerned about the manner of the splice. Twisting and electrical tape are not a reliable splicing method. Even if it is working properly initially, there is too much chance of problems to occur over time as the cables move slightly (temp changes, building vibrations, large vehicles driving by, etc).
The very first type of problem you can experience would be the inability to connect over the cable. Since it appears you can do so, then the next problem would be frame loss, often from corrupted frames that will get dropped when they fail a consistency check.
If you have real equipment on both sides of this link, you should be able to view the interface statistics and see how many frames are being dropped as well as the reasons.
My suggestion would be to wire the socket as a single connection and then if you later decide to use it as two cables, just use a splitter (a little piece of cable with one plug and two sockets) at both ends. Just make sure to get a splitter for Ethernet (which connects two pairs to one socket and two to another) and not ISDN (which just connects both sockets in parallel).
Connecting the wires to two sockets in parallel may cause signal problems for the gigabit connection and you (or someone else) will forget to use it correctly at least once and plug one end of the cable as a single connection while connecting two computers at the other end.
Upd.
Internal wiring of ethernet splitter
Splitter kind 1, kind 2 useful for patchpanel
Best Answer
Nowodays, many ethernet interfaces are 'auto MDI/MDIX'.
They detect the type of device connected and if needed reverse internally Transmit and Receive.
This allow connection of 2 devices of the same layer with straight-through cable.
APIPA is specifically made to provide IP addresses and allow IP communication in a network where there's no DHCP server.
There's a subnet mask associated with APIPA-assigned IP addresses, it is 255.255.0.0 (I.E. /16). On a windows 7 machine this subnet mask is shown by "ipconfig /all".
Maybe windows 8 or 10 hide it because it's implicit with APIPA, but I cannot check it right now.