How is the link initialization implemented in Ethernet?

In point-to-point scenario, it's straighforward. In ethernet, I wonder which to which will start this process? Will every pair of stations of the ethernet intialize link, or, only each station initialize a link with the router?

Thanks,

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Comments

networker050184

Are you talking about routing adjacency?

fly351

or media access at Layer 2?

johnifanx98

networker050184 wrote: »

Are you talking about routing adjacency?

I mean the three-way handshake. In point-to-point scenario, this happens between the two ends. In ethernet, there are a bunch of stations and a router. Will every two of them do this handshake?

fly351

hmm I think I know what your trying to say, but I think you are confused on the terminology, protocols, and the OSI reference layer. Generally, you won't have a "bunch of stations" connecting directly to a router. They would be connected to a switch or hub and a trunk from the switch to the router.

btw... Router's operate at Layer 3. Layer 4 "three way handshakes" do not exist between a router and a host PC.

networker050184

Still not sure what you are talking about exactly. Do you mean the TCP three way handshake? If so I think you are confused on what this is used for.

johnifanx98

networker050184 wrote: »

Still not sure what you are talking about exactly. Do you mean the TCP three way handshake? If so I think you are confused on what this is used for.

The textbook tells me that DLC layer has a similar procedure as TCP's three-way-handshake though they differ somehow. For example, when two routers are connected, they must initialize the link in DLC layer first. In the case of a subnet, I assume similar processes will happen. Just curious how links are initialized among multiple stations...

networker050184

I'm still not 100% sure what you are asking, but I think ARP might be what you are looking for? Thats how devices discover each other at L2.

penguinking

I think he's talking about how packets are actually pushed out from ports. And if that's the case, then I think he just needs to know that on local (layer 2) networks where a layer 3 router isn't being used, a packet (still just a frame at this point) experiences a delay in queuing, and that delay is called latency. The delay is usually related to a switch looking up the hardware address (a globally unique MAC address in every NIC on the planet) in what is called the CAM table. This table is maintained so that frames that reach the switch are filtered/forwarded to proper host quickly and efficiently, and any delay is measured in milliseconds and is, again, called latency. Queuing delay is a little different in that when multiple frames reach the switch, they all can't be pushed out simultaneously and must therefore be put into a waiting line of sorts. There's also latency related to whether you're using full duplex links, where CSMA-CD (Carrier Sense Multiple Access with Collision Detection) is needed to avoid packet collisions. All modern switches and cables are full duplex.

Your 3-way handshake reference is only related to layer 4 TCP connections, where the connection itself is being negotiated between two hosts. It's not related to local networks, or routers, or anything like that. It's just a way of describing how two remote computers negotiate a connection over the Internet (so I guess, technically, 3-way handshakes are only relevant when separated into different subnets).

fly351

johnifanx98 wrote: »

The textbook tells me that DLC layer has a similar procedure as TCP's three-way-handshake though they differ somehow. For example, when two routers are connected, they must initialize the link in DLC layer first. In the case of a subnet, I assume similar processes will happen. Just curious how links are initialized among multiple stations...

Can you tell us what textbook you are using? Between the people here on TE, I am sure someone has the same book and we can figure out what you are having trouble understanding

johnifanx98

fly351 wrote: »

Can you tell us what textbook you are using? Between the people here on TE, I am sure someone has the same book and we can figure out what you are having trouble understanding

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