Transceivers are designed for use when using multiple types of cabling. Enterprise servers, switches, and routers, are available with modular hot-swappable transceivers for different types of fiber optic and copper connections. 

They operate at the data link layer which is responsible for putting the data onto the wire and pulling it off the wire (send/receive). 

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Modular Transceivers

A growing company needed to upgrade its network infrastructure to handle increased bandwidth demands. However, they had a mix of different fiber optic cable types across their various buildings.  Replacing all the cables would be expensive and time-consuming.  The solution? Modular transceivers! By utilizing transceivers compatible with their existing network switches but designed for the specific fiber they needed, the company could easily upgrade their network without ripping out all their existing cabling. The modularity of the transceivers saved them time and money.

Example

A conference center was hosting a major event with international participants. They needed to ensure a reliable and high-speed network connection for all attendees,  However,  some of the conference rooms were located at a significant distance from the main network hub. Traditional copper cables wouldn't suffice for such long distances.  The solution? Modular transceivers designed for fiber optic cables.  By installing fiber optic cables and compatible transceivers in the remote conference rooms, the center could provide a strong and reliable network connection for all participants no matter their location.

Example

Duplex Settings

Half-Duplex - data flows in one direction at a time

Full Duplex - data flows in both directions at once

Different transceivers are designed to work at different optical wavelengths (typically 850 nm, 1300 nm, or 1550 nm) and support different Ethernet standards and bit rates. This means it is important to check the manufacturer's documentation for the interface to ensure the correct fiber type is used, not only for the fiber optic cable, but also for the fiber patch cords used to connect to it at each end. Mismatches between cable, patch cords, and interfaces may lead to significant signal loss.

​Transceiver Mismatch Issues

Physical Obstacles
Radio Wave interference
Power Levels
Faulty Devices

Signal Strength Issues

Based on:
Length of cable
Connectors
Splices

Fiber Loss

Depends, but loss budget must be less than power budget

if Tx is -8 dBm and Rx is -15dBm then power budget is 7db (to make up the difference)

Loss Budgets

optical link budget - amount of loss suffered by all components along a fiber transmission path

Fiber Signal Facts

John, an IT technician, was troubleshooting a network outage in a recently renovated office space.  Everything seemed to be connected properly, but no devices in the new section could access the network.  John double-checked the cables and switch ports, but everything looked good.  Finally, he realized a crucial detail - the new network jacks were designed for a different type of fiber optic connector than the transceivers installed in the switch.  This mismatch in port types prevented any signal from passing through, causing the network outage.  John quickly replaced the transceivers with ones compatible with the new jacks, and voila! The network in the new office space sprang to life.

Example

Sarah was video conferencing with a colleague located in a different country. The call started smoothly, but soon the video became choppy and pixelated, making communication difficult.  Sarah suspected a network issue.  She checked the network monitoring tools and noticed the signal strength coming from the transceiver connected to the video conferencing equipment was dropping significantly.  This weak signal resulted in poor video quality.  The problem could be due to a faulty transceiver, a damaged fiber optic cable, or even dust on the transceiver connector.  By diagnosing the cause of the weak signal and taking corrective action (replacing the transceiver, repairing the cable, or cleaning the connector), Sarah could ensure clear and uninterrupted video calls.

Example

preamble and sfd are used for clock sync as part of CSMA/CD to identify collisions

consists of 8 bytes, SFD ends with 11

Technically not part of the frame

Preamble

2 bytes
indicates type of protocol in the frame payload
IPv4 = 0x0800
IPv6 = 0x86DD

EtherType

Known as the FCS = frame check sequence

4 bytes

based on a calculation; if receiver performs same calculation, it will accept the frame

if fails, a higher layer will handle retransmission

Error Checking

Examine the frame

In a frame, MAC addresses refer to source and destination!

Examine the MAC addresses

Broadcast - exactly like our all-call over speakers

Broadcast - ARPs / network discovery / Wake On Lan

Broadcasts - when there are too many, NETWORK ISSUES!

Broadcasts - takes time to process = slow network performance

Unicast- one sent to an individual host

Destination MAC is the HOST MAC