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A random/stupid question regarding 2 separate subjects: 802.3 and EDGE/2G/3G/4G/LTE

My first question is: according to my study book, 802.3Z is the only Ethernet protocol that has fiber cabling, and a maximum length of 5000 meters. Why is that? Why isn’t fiber better suited to faster speeds like 10 Gig Ethernet, and why is it the only standard that uses fiber cabling?

My second question: From a topology standpoint, how does mobile internet work? As in, are the towers just massive WLAN access points? If so, is every switch from tower to tower interconnected instead of using routers? I remember having this question a bit ago and I was totally perplexed. I’m hoping one of you guys could shed some light.

EDIT: nevermind, I misread the first part and the second part wasn’t a very good question in the first place lol.

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3 points · 9 days ago

according to my study book, 802.3Z is the only Ethernet protocol that has fiber cabling

I'm guessing you're reading that incorrectly. Regardless, the above statement is false. 802.3z does however contain all the 1Gb glass fiber standards. There are plenty of fiber standards at 10, 25, 40, and 100+ Gb, depending upon how far you want to travel and what fiber you want to use.


are the towers just massive WLAN access points?

they're not WLAN, but yes, they are point-to-point radios connected to some other larger network.

is every switch from tower to tower interconnected instead of using routers?

This question doesn't make sense. Yes, the towers are connected; sometimes that connection may use a router.

Original Poster1 point · 9 days ago · edited 9 days ago

I’m stupid. The table just shows examples of Ethernet standards regarding cabling, not all of them. Is there a standard for say, 10 gig Ethernet for fiber?

And that was sort of my question...I wasn’t sure if the towers would use routers or switches to communicate...it doesn’t make sense now that I think about it...it really was a stupid question lol.

I apologize

EDIT: I asked about switches because wouldn’t all of the towers physically be on the same network, not different networks?

3 points · 9 days ago

Is there a standard for say, 10 gig Ethernet for fiber?

There's several. Generally, however, when talking about Ethernet standards, we use the names, not the IEEE designations. So the 4-5 10Gbase-*R names would be far more common. I don't know many people who memorize more than a half-dozen IEEE standard numbers--and none of those are speed or physical standards.

I asked about switches because wouldn’t all of the towers physically be on the same network, not different networks?

"Network" is a pretty vague term here. An entire carrier's 4g infrastructure can be considered a network, or you could be talking about a single L2 domain. While I don't work in mobile, the site-to-site links are almost certainly L3 to increase efficiency. But links like that are done switch-to-switch very regularly. However, I would place my money on each tower having one serious router to handle the interconnect as I'm not sure the tower-to-tower links are necessarily Ethernet transport.

10 Gigabit Ethernet

10 Gigabit Ethernet (10GE, 10GbE, or 10 GigE) is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. It was first defined by the IEEE 802.3ae-2002 standard. Unlike previous Ethernet standards, 10 Gigabit Ethernet defines only full-duplex point-to-point links which are generally connected by network switches; shared-medium CSMA/CD operation has not been carried over from the previous generations Ethernet standards so half-duplex operation and repeater hubs do not exist in 10GbE.

The 10 Gigabit Ethernet standard encompasses a number of different physical layer (PHY) standards. A networking device, such as a switch or a network interface controller may have different PHY types through pluggable PHY modules, such as those based on SFP+.


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Original Poster0 points · 9 days ago

It looks like 10GBASE-ZR would be the longest range 10GB connection?

Okay, so again, as I’m new (I’m nowhere near getting my CCENT.), let me see if I understand what you said: so, a carriers whole system of towers could be considered one network, which could be done in layer 2 through switches. But if it’s in Layer 3 using routers, they’d be a VPN/VLAN, at least if they were made to be a part of the same network? But it could also be a combination of L2 and L3 devices creating a single large network? And as I said to the other person, if this question will take too long to answer, don’t feel obligated or do it if it feels like a waste of time. I don’t want to waste others valuable time with simple questions.

Also, on a side note, these networks would be absolute hell to troubleshoot.

Ethernet is a standard. Fiber cabling is different standards. Ethernet can run over fiber or copper. The transceiver standards determine the physical representation of the data over the specific mediums.

wouldn’t all of the towers physically be on the same network, not different networks?

No, they are not necessarily. The towers normally use ISPs for connectivity. It could be MPLS L3VPN services or L2 services, such as L2VPN, VPLS, VLANs, etc. Some towers also have P2P radios to get connectivity to neighboring towers if physical connectivity is unavailable or too expensive.

Original Poster1 point · 9 days ago

Unfortunately, I’m so new to this that most of that went over my head. I’m assuming VPN means virtual private network and VLAN is virtual LAN, and I get the concept behind both of those if so. I get the P2P part, that makes sense to me. If L3 means layer 3 and L2 means layer 2, then I don’t know the difference between L2VPN and L3VPN...for the L2 one, would that somehow be a VPN done through cabling or switches (I believe I was told L2 can have switches?)?

And if this will take too long to explain, please don’t bother trying to as I don’t want to waste anybody’s time with a question that has no real importance other than curiosity.

Mobile internet: base station builds tunnels over transport to ggsn (or sgsn) when the terminal switches base station the tunnel is moved to new basestation.

The network can be routed/switched/direct connections/whatever. The packet-core has not changed much since gprs days.

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