WAN infrastructure types

FrankGuthrie

Ok, in studying for my CCNA I learned that there are 3 types of WAN Infrastructures, but I still have questions about the underlying hardware.

- Leased line - The concept is clear, you have a dedicated line for the customer. But what type of line is used? Fiber Ethernet? Is fiber alway used?
- Circuit switched - Same question, what type of line is used? Fiber, Ethernet something different??
- Packet switched - Same question, what type of line is used? Fiber, Ethernet something different??

Also what is the difference betwewen Circuit switched and Packet switch lines?? Packet do travel over both connections, right? Isn't a PVC/DLCI a kind of circuit??

I'm working at a service provider as a junior netwrk engineer, but these cncept are a bit abstact.

I used to think thaht ethernet was a type of cable, but is just the technology run over an UTP cable, theze day's you even can run Five channel over Ethernet, but I ueds to think thaht Fiber really meant Fiber, as the underlying hardware/infrastructure

Look like they can push every thing these day over any type of media, sometime this all get a bit confusing.

DirtySouth

One thing that really used to confuse me was all the terms and acronyms that get thrown around when talking networking, circuits and cabling. It's especially bad when in the data center like SR, LR, SFP+, CX4, QSFP+...etc. You have to try and separate the difference between protocols and cable medium because the two are often confused. Also, the connectors on the ends of the cabling are often confused with the cable itself.

To answer your question, a leased circuit can be a T1, DS3, Metro-Ethernet (Metro-E), Frame-Relay...etc. All of those types of circuits can have different types of median "hand-offs". For example, a Metro-E circuit, which is very common these days, can be handed off UTP, Single Mode or Multi-mode fiber. This is not an all-encompassing list. I'm just hitting the high points from my experience. A T1 could be handed off STP or sometimes UTP (Cat 5/6) or Serial. It all depends on the provider and what the customer has asked for. Typically, the customer can negotiate with the provider for what type of hand-off they want in order to accommodate whatever kind of router or L3-switch they have onsite.

FrankGuthrie

DirtySouth wrote: »

To answer your question, a leased circuit can be a T1, DS3, Metro-Ethernet (Metro-E), Frame-Relay...etc. All of those types of circuits can have different types of median "hand-offs". For example, a Metro-E circuit, which is very common these days, can be handed off UTP, Single Mode or Multi-mode fiber. This is not an all-encompassing list. I'm just hitting the high points from my experience. A T1 could be handed off STP or sometimes UTP (Cat 5/6) or Serial. It all depends on the provider and what the customer has asked for. Typically, the customer can negotiate with the provider for what type of hand-off they want in order to accommodate whatever kind of router or L3-switch they have onsite.

But what is the physical attributes of a frame relay line? is it send over UTP, Fiber? The concept is to abtract for me to graps my head around it.

Also Metro Ethernet, is that send over UTP? In my head, Ethernet is send over a UTP cable, but I might change that notion of linking certain technologies to physical hardware.

Also the difference between packet switching and circuit switching is not really clear to me. Packet switching I get, at least I think, this is basically what a switch does when sending packets, for example when we send an email, it get chopped in smaller pakcet to get switched/routed to it's destination.

But how does Circuit circuit work, or Am making it more difficult that it is?

Writting this, I just got a light bulb moment. A circuit switch is probably switching based on Circuits, so the switch doesn't look in the packet in the L2 an L3 adresses. I think I just got it

theodoxa

FrankGuthrie wrote: »

But what is the physical attributes of a frame relay line? is it send over UTP, Fiber? The concept is to abtract for me to graps my head around it.

Frame Relay in a Layer 2 Protocol/Encapsulation. It can be transported over a few different physical media. T1 is probably the most common in the real world. In CCNA labs it is usually transported over a Serial cable: HD60 (WIC-1T, HWIC-1T, NM-4T, NM-4A/S, NM-8A/S) or Smart Serial (WIC-2T, HWIC-2T, WIC-2A/S, HWIC-4A/S).

Also Metro Ethernet, is that send over UTP? In my head, Ethernet is send over a UTP cable, but I might change that notion of linking certain technologies to physical hardware.

Ethernet can be transported over UTP (Unshielded Twisted Pair), STP (Shielded Twisted Pair), or Fiber (Multi- or Single-Mode).

Also the difference between packet switching and circuit switching is not really clear to me.

Packet switching breaks data into packets and each packet could theoretically take a different path through the network (e.g. Data sent over the Internet). Circuit switching creates a dedicated circuit through the network over which the data travels (e.g. a POTS Telephone Call). Of course, the whole phone comparison is changing. AT&T and the Telcos are trying their da**edist to get the FCC to let them do away with [Circuit Switched] POTS and go strictly [Packet Switched] VoIP.

But how does Circuit circuit work, or Am making it more difficult that it is?

Think of the switchboards depicted in old movies where an operator connects a wire between two plugs to complete a phone call for someone. The modern circuit is the same idea, but instead of an operator plugging and unplugging cables, switches flip back and forth between connections to create circuits.

Writting this, I just got a light bulb moment. A circuit switch is probably switching based on Circuits, so the switch doesn't look in the packet in the L2 an L3 adresses. I think I just got it

Correct.

FrankGuthrie

theodoxa wrote: »

Frame Relay in a Layer 2 Protocol/Encapsulation. It can be transported over a few different physical media. T1 is probably the most common in the real world. In CCNA labs it is usually transported over a Serial cable: HD60 (WIC-1T, HWIC-1T, NM-4T, NM-4A/S, NM-8A/S) or Smart Serial (WIC-2T, HWIC-2T, WIC-2A/S, HWIC-4A/S).

Does it matter how you configure Frame Relay, depending on the media (broadcast vs. non-broadcast)?


Ethernet can be transported over UTP (Unshielded Twisted Pair), STP (Shielded Twisted Pair), or Fiber (Multi- or Single-Mode).

Did not know it could be transported over Fiber, the other way around you have Fibre Channel over Ethernet, so need to learn to see the protocol and the underlying cabling as seperate.

Packet switching breaks data into packets and each packet could theoretically take a different path through the network (e.g. Data sent over the Internet). Circuit switching creates a dedicated circuit through the network over which the data travels (e.g. a POTS Telephone Call). Of course, the whole phone comparison is changing. AT&T and the Telcos are trying their da**edist to get the FCC to let them do away with [Circuit Switched] POTS and go strictly [Packet Switched] VoIP.

Above story is very clear

Thanks for taking the time to reply in such a extensive manner. It is much appreciated sir/madam.

theodoxa

FrankGuthrie wrote: »

Does it matter how you configure Frame Relay, depending on the media (broadcast vs. non-broadcast)?

It's not really the media that is broadcast or non-broadcast, but the Layer 2 protocols (Ethernet, Frame Relay, etc...) To make things even muddier, some of what we think of as media (e.g. T1) are really Layer 1 Protocols created to get more bandwidth out of existing media.

Physical layer - Wikipedia, the free encyclopedia

BTW, I forgot to mention that the original Ethernet (ThinNet/10Base2, ThickNet/10Base5) actually used Coaxial cable. I doubt you will see ThinNet/ThickNet Ethernet these days due to its significant limitations. The computer lab when I was in High School used ThinNet.

10BASE2 - Wikipedia, the free encyclopedia
10BASE5 - Wikipedia, the free encyclopedia

FrankGuthrie

theodoxa wrote: »

It's not really the media that is broadcast or non-broadcast, but the Layer 2 protocols (Ethernet, Frame Relay, etc...) To make things even muddier, some of what we think of as media (e.g. T1) are really Layer 1 Protocols created to get more bandwidth out of existing media.


Physical layer - Wikipedia, the free encyclopedia

Interesting. I never thought off Layer 1 as a layer with protocols. I don't know why, but I always saw Layer 1 as pure hardware, but I now better understand Layer 1 by that comment. A protocol which is created so vendors can make hardware according to a standard! I feel like I'm being schooled here, which is not a bad thing . For some reason I saw Layer 1 as the hardware itself, so the hardware as part of Layer 1, but it's not, it sits below it, Layer 0.

Also T1 is just an aggregate of multiple ISDN line, isn't it?

BTW, I forgot to mention that the original Ethernet (ThinNet/10Base2, ThickNet/10Base5) actually used Coaxial cable. I doubt you will see ThinNet/ThickNet Ethernet these days due to its significant limitations. The computer lab when I was in High School used ThinNet.

10BASE2 - Wikipedia, the free encyclopedia
10BASE5 - Wikipedia, the free encyclopedia

Thank you for the class

theodoxa

There's not really a Layer 0 per se. Layer 1 covers both the hardware and the signaling. According to Wikipedia T1 is the hardware and DS1 is the signaling, though these terms are used interchangeably in my experience.

Also T1 is just an aggregate of multiple ISDN line, isn't it?

Its a standard for getting more channels (phone calls) on a POTS trunk line. The main thing it did was make it digital. By going digital [over the existing lines] they were able to get 24 phone calls on the same line that previously could only carry 1 phone call at a time. ISDN BRI supports 2 channels/phone calls. ISDN PRI is similar to T1, except that it only supports 23 channels/calls. The 24th channel is used exclusively for signaling.

Wikipedia wrote:

Before the digital T-1 system, trunks could only carry one telephone call at a time; each call was a voice-frequencyanalog signal. A T-1 trunk could transmit 24 telephone calls at a time, because it used a digital carrier signal called Digital Signal 1 (DS-1). ^[1] DS-1 is a communications protocol for multiplexing the bitstreams of up to 24 telephone calls

xXErebuS

theodoxa wrote: »

It's not really the media that is broadcast or non-broadcast, but the Layer 2 protocols (Ethernet, Frame Relay, etc...) To make things even muddier, some of what we think of as media (e.g. T1) are really Layer 1 Protocols created to get more bandwidth out of existing media.

Physical layer - Wikipedia, the free encyclopedia

BTW, I forgot to mention that the original Ethernet (ThinNet/10Base2, ThickNet/10Base5) actually used Coaxial cable. I doubt you will see ThinNet/ThickNet Ethernet these days due to its significant limitations. The computer lab when I was in High School used ThinNet.

10BASE2 - Wikipedia, the free encyclopedia
10BASE5 - Wikipedia, the free encyclopedia

Correct, it does matter how you configure frame relay, but not b/c of medium... people see that it doesn't do broadcast but in most cases the biggest issue is that by default it doesn't forward multicast.... what type of IP addresses do most dynamic routing protocols use to setup relations?

I think you have it, but think of it as a highway (medium) and the cars being your protocols. You're EIGRP (a honda civic) whether you're on concrete; asphalt; or (hopefully not) dirt. Now somethings are not suited on those mediums, for example a snowmobile on a railroad track.