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We have two interfaces on two routers, which are connected with a serial cable. Both of the interfaces are in network 224.0.0.0/24. So one interface on the first router has IP address 224.0.0.1/24. Other interface on second router has IP address 224.0.0.2/24. Both routers are then connected to indenpendent switches.

Here is the network topology: mapping of the situation

(It's made in Cisco Packet Tracer and you can see that IP addresses are not configured and interfaces are shutted down, but that's not important now.)

What type of network is 224.0.0.0/24 in this case:

  • Local Area Network?

  • Metropolitan Area Network?

  • Wide Area Network?

Our teacher at school was referring to it as WAN connection. But I am not sure, since WAN connections are much larger with more devices inside. So that's why there is confusion.

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    "placed somewhere"... ermm... where, how, what connects them...? – Tetsujin May 19 '18 at 15:43
  • They are just connected with some serial cable. – patrikkXpp May 19 '18 at 15:48
  • "some serial cable"... no clearer in the slightest. – Tetsujin May 19 '18 at 15:49
  • 2 routers connected with serial cable, what more is it needed to know? – patrikkXpp May 19 '18 at 15:52
3

The teacher is correct.

Cisco learning refers to serial card equipment as WAN cards. That doesn't mean you can't use it locally. But in production environments you would find them connected as wide area network equipment.

There isn't really any reason to use these router to router locally because they are extremely slow compared to Ethernet interfaces.

Sadly, just like some of the other legacy concepts, (like CSMA/CD) you will need to know how to setup DTE (Data terminal equipment) and DCE (Data communications equipment) for the ICND1/2 & CCNA. The primary difference between DCE and DTE is clocking; DCE can provide it, DTE cannot. A easy way to remember the two for tests is this, DTE = data transmitting equipment. DCE = data clocking equipment.

Also, Attie is right about the IP. Use either class A/B or C private ranges. (Rfc1918)

Reference: https://www.cisco.com/c/en/us/support/docs/routers/7200-series-routers/12219-17.html

3

Two routers connected with a serial cable are just that - two routers connected with a serial cable.

Until you tell us about the physical layout of your hypothetical network, we can't use terms like LAN / WAN / etc...

Note how these terms are all tied to the physical configuration and size of a network. We don't use these terms to describe logical configuration (i.e: "two routers connected with a serial cable")


Additionally, a "serial cable" implies RS-232 (possibly RS-422), and isn't really considered to be "networking" within the in modern definition - it's used all over the place for configuration and direct interfacing.

In some industries RS-485 is used for point to multi-point networking (with a specific master)... but if you're talking about this, then you're not talking about IP / Routing / X Area Networks.

I suspect you don't mean "serial cable" - i.e: DE-9 (aka DB-9):

serial cable

Instead, you probably mean, "network cable" - i.e: CAT5 / CAT5e / CAT6, terminated with RJ-45 connectors:

network cable


With your addition of a diagram, we can now establish that you probably do indeed mean "network cable". In this case, as mentioned above, the physical / geographic size of the network determines what it is called (LAN / MAN / WAN / etc...).

  • If Network A (172.16.0.0/16) and Network B (192.168.0.0/24) are in the same physical building, then it's probably still referred to as a LAN. Just with two segments that have routing between them. Arguably it could be considered two LANs with routed access to each other.
  • If Network A and Network B are in two separate buildings in the same neighbourhood, then it's possible that it could be considered a MAN.
  • If Network A and Network B are in two separate buildings in two separate cities, then they could be considered a WAN.

The whole network is considered for this terminology - not just the link between the routers.

It's highly likely that Network A is a LAN, and Network B is a LAN.

If you want to know what the "red link" is called, then one of these could probably fit:

  • Patch cable
  • Network cable
  • Fiber optic cable
  • Leased Line
  • VPN

To offer an alternate explanation: "Teacher at school was referring to it as WAN connection"... he is probably familiar with consumer (home) routers, which mark "the port that connects to the internet" with the label "WAN". It doesn't mean that the link (and only the link) is a WAN, but rather that the consumer router connects to the WAN (i.e: Internet) via this port.

consumer router


To poke further issues at your question and setup, 224.0.0.0/4 is reserved for multicast addressing. If you are using this for any other purpose, then you may (will) run into odd / unexpected behaviour.

  • I meant two interfaces on two routers connected with serial cable. They are in some network, for example 224.0.0.0/24. One interface on first router has ip address 224.0.0.1/24 and one interface on second router has ip address 224.0.0.2/24. Both of the routers can be further connected to indenpendent switches. So can we talk about some network type now? What type of network is 224.0.0.0/24 in this case? – patrikkXpp May 19 '18 at 16:37
  • It would be far better if you included all the detail in your actual question, not in comments. Comments are ephemeral & can be deleted at any time. The only thing that will stand is the question & answer[s]. – Tetsujin May 19 '18 at 16:54
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    It's entirely practical to connect 2 appropriately wired routers using a serial (ie RS232) cable. While it's not typical, a null modem cable could act as a stand in for a leased line or dialup connection from yesteryear, and indeed it sounds like this is what's being done here. Not very forward thinking bearing in mind the limitations of the technology. – davidgo May 20 '18 at 8:48
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    @attie, Cisco serial is actually a WAN connection still used in some areas. Usually refered as DTE/DCE serial. It can be any of the following ( EIA/TIA-232, X.21, V.35, EIA/TIA-449, EIA-530, and HSSI) Just for reference, Cisco calls these WAN connections. seriously though, This smells like CCNA homework to me. cisco.com/c/en/us/support/docs/routers/7200-series-routers/… – Tim_Stewart May 21 '18 at 19:28
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    @attie, lol they are awful, the bandwidth is archaic. Cisco torments their students with forcing them to learn it. – Tim_Stewart May 21 '18 at 21:10

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