DSA Terminology

[Arınç ÜNAL]

On 12.09.2022 00:28, Rich Brown wrote:
> I think I see where I went wrong. I have updated the definitions in the DSA Terminology page to incorporate what I understand from this conversation. See: https://openwrt.org/docs/guide-user/network/dsa/dsa-mini-tutorial#terminology
> 
> Is this getting closer to a set of good definitions? Thanks.

It's much better than before. Though, the terminology section explains 
computer networking rather than DSA.

Interfaces and networks are beyond any sort of classification under any 
OSI layer.

Interface is what makes the data transfer happen. It's not a protocol 
you can classify under an OSI layer.

Network is the representation of computers (anything with the ability of 
computing) sending data to each other through interfaces. It represents 
the EVERY THING of communication.

Each network entry on OpenWrt would mean that your router is a part of 
that network connected through an interface. Then, you can configure 
your computer (call this our router) to transmit and receive data in 
certain way.

For this network which we're connected to, through this interface:
Send data with this IP address, analyse received data for this range of 
IP addresses and act different when something we defined matches. Send 
data with this MAC address, listen for this MAC address on the received 
data. Send DHCP packets, listen for DHCP packets, etc. Does this make sense?

Getting back to DSA, DSA doesn't have much to do with any of these. Like 
it's said multiple times in this thread (under a few different 
subjects), at its core, it creates a network interface for each switch 
port. This documentation should be enough to explain the terminology.

https://github.com/torvalds/linux/blob/master/Documentation/networking/dsa/dsa.rst

On top of this, I'd like to give two configuration examples for any 
ethernet interfaces, including the interfaces created by DSA.

- One without bridge VLAN filtering
   - Only lan interfaces on the bridge, VLAN-unaware forwarding.
     - Keep wan interface separate.
   - No bridge, use each interface separately.

- One with bridge VLAN filtering
   - All interfaces on the bridge, VLAN-aware forwarding.

My "Converting to DSA" page already follows the second configuration.

Arınç

> 
> Rich
> 
>> On Sep 10, 2022, at 9:47 AM, Arınç ÜNAL <arinc.unal at arinc9.com> wrote:
>>
>> On 10.09.2022 14:59, Rich Brown wrote:
>>> I got the following definitions from Arınç, I am taking the liberty of opening this to the entire list, so we can refine these definitions together. I include some questions in-line to clarify the definitions.
>>>>>> As a start, certain terms have cropped up multiple times in this discussion. Could I ask for definitions for the following terms?
>>>>>>
>>>>>> Network:
>>>>
>>>> A network represents a group of computers communicating with each other.
>>> 	Are there other constraints for what comprises a network? For example, which of these would be considered to be "a network" in our DSA discussion?
>>> 	- Computers in the same subnet range
>>
>> That's a network.
>>
>>> 	- Computers on the same VLAN
>>
>> That's a network.
>>
>>> 	- Computers physically attached to a switch or bridge (perhaps on different subnets)
>>
>> That'd be multiple networks but I guess that's technically a single network since computers on different subnets can still communicate with each other at the second layer.
>>
>> The means of delivering data in between (switch, bridge etc.) is also expected on the examples above.
>>
>>> 	- Are there other synonyms for "network"?
>>
>> I don't believe so.
>>
>>>>>> Network Interface:
>>>>
>>>> A network interface is the point of interconnection, implemented on the software, between computers.
>>> 	- I had earlier written "... physical connections that convey bits/frames to other computers ... such as individual Ethernet switch ports, wireless radios, USB networking devices, VLANs, or virtual ethernets."
>>> 	- How much of this is correct? What should be added or removed?
>>> 	- What about bridges, tunnels, alias interfaces - include or exclude them? Why?
>>> 	- Must a network interface to be "implemented in software"?
>>
>> That's what a network interface is. It's a software term.
>>
>>> 	- Or do you mean that the network interface is the "software representation" of a physical connection?
>>
>> Software representation of interconnection, doesn't have to be physical.
>>
>>>>>> Interface:
>>>>
>>>> Short for network interface.
>>> 	- Can we *always* treat this as a synonym for "network interface"?
>>
>> I believe so.
>>
>>>>>> Device:
>>>>
>>>> Another term for network interface, used a lot on Linux kernel development.
>>> 	- Can we *always* treat this as a synonym for "network interface"?
>>
>> No. Outside of Linux driver development, I don't see this widely used in computer networking software.
>>
>>>>>> Netdev:
>>>>
>>>> A mailing list for all network-related Linux stuff. https://docs.kernel.org/process/maintainer-netdev.html#what-is-netdev
>>> 	- Is "netdev" used commonly in DSA/OpenWrt as a formal term?
>>> 	- If not (and if we need to rename something in config files), could the term "netdev" provide a new word that isn't ambiguous?
>>
>> I don't understand what you're getting at?
>>
>> Arınç
>