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I once dialed up on my router so I did not need to create a broadband connection on my PC.

Now, I dial up on my PC so I need to create a broadband connection on my PC. There are two active networks on my PC: One is the broadband connection (PPPoE) and the other is the Ethernet. I wonder the relation between them.

Does the traffic go through the broadband connection first, then through the ethernet, then go to the router?

The following is the route table on the PC:

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0      192.168.1.1      192.168.1.2   4260
          0.0.0.0          0.0.0.0         On-link   202.212.101.132     36
  202.212.101.132  255.255.255.255         On-link   202.212.101.132    291
        127.0.0.0        255.0.0.0         On-link         127.0.0.1   4556
        127.0.0.1  255.255.255.255         On-link         127.0.0.1   4556
  127.255.255.255  255.255.255.255         On-link         127.0.0.1   4556
      192.168.1.0    255.255.255.0         On-link       192.168.1.2   4516
      192.168.1.2  255.255.255.255         On-link       192.168.1.2   4516
    192.168.1.255  255.255.255.255         On-link       192.168.1.2   4516
        224.0.0.0        240.0.0.0         On-link         127.0.0.1   4556
        224.0.0.0        240.0.0.0         On-link       192.168.1.2   4516
        224.0.0.0        240.0.0.0         On-link   202.212.101.132     36
  255.255.255.255  255.255.255.255         On-link         127.0.0.1   4556
  255.255.255.255  255.255.255.255         On-link       192.168.1.2   4516
  255.255.255.255  255.255.255.255         On-link   202.212.101.132    291
===========================================================================

The IP address 192.168.1.2 is assigned to the ethernet and 202.212.101.132 is assigned to the broadband connection.

I only see the traffic goes to the broadband connection (line 2) but I cannot figure out the role of the ethernet here.

But I think the ethernet does play a role because it corresponds to the physical network adapter which I connect to the router.

Giacomo1968
  • 58,727
William
  • 323

2 Answers2

17

I think this answer needs some background context to clear some things up, because your Question uses networking terms in a very unusual way that makes it hard to parse out what you may be asking.

Back before broadband, we got online through dial-up modems over plain old telephone service landlines. The protocol we used to send Internet traffic over those dial-up modems was called PPP. Dial-up ISPs created network infrastructure based on PPP, so their infrastructure routers would expect to receive lots of customer PPP connections forwarded from their pool of modems that received the customers' dial-up calls.

At the same time, in offices and some nerds' homes, people were building "local area networks" (LANs) with Ethernet cables and Ethernet hubs/switches. Ethernet LANs allowed for people to share printers and do multiplayer LAN gaming and share files with other LAN users via file servers, and access and database servers and other corporate IT infrastructure.

When broadband technologies like DSL came along, it replaced "dialing up". Unlike a dial-up modem, a DSL modem is a device that's always connected to the Internet via DSL, and just translates between DSL and Ethernet, connecting your whole Ethernet LAN to the Internet full time, without needing to make a PPP connection. But the problem for many ISPs at the time was that their infrastructure was still based on PPP. So some ISPs, instead of fully modernizing, decided to keep PPP involved. So PPP-over-Ethernet (PPPoE) was created so those ISPs that wanted to keep their PPP-based infrastructure could do so, even though their DSL customers weren't actually dialing up any more; they were using Ethernet to connect to a DSL modem.

Because PPP was still associated with dial-up modems in consumers' minds, some PPPoE client apps were called "broadband dialers" even though there's no dialing going on in broadband. A PPPoE connection is a lot like a VPN tunnel, but without encryption. In fact, many VPN protocols use PPP on the inside of the encrypted tunnel.

So it sounds like you're running a PPPoE client that calls itself a "Broadband Connection". It looks like your PPPoE client has successfully made a connection to your ISP's PPPoE "Access Concentrator" (that's the name for the ISP's big PPPoE server/router that handles the incoming PPPoE connections), which suggests you are on the same Ethernet LAN as a DSL modem. The only mystery to me is why you also have a router on your Ethernet LAN apparently doing NAT and DHCP. Usually the device doing NAT and DHCP has to be the device doing PPPoE. It makes me wonder if you have your DSL modem connected to a LAN port of the router.

Spiff
  • 110,156
1

What is the relation between broadband connection (PPPoE) and ethernet?

Your PC uses PPPoE to establish a tunnel which allows to carry IP-related information before you PC has a routeable IP address. IPCP (Internet Protocol Control Protocol) could be carried through that tunnel to assign you PC an IP address. IPCP is one of many control protocols stacked on PPP.

Does the traffic go through the broadband connection first, then through the ethernet, then go to the router?

Downstream, the traffic goes via whatever access network the ISP uses, then through the router (I guess you mean the device installed by the ISP), and then through Ethernet between the router and your PC. PPP is used to tunnel all the way from your PC into the ISP's network.

viator
  • 11