What Is the Difference between 100G Active Optic Cable and 100G Direct Attach Cable?

---

We
know that both 100G
active optic cables (AOC) and 100G direct attach cables (DAC) are used
to transmit data. However, there are some differences between 100G active optic
cables and 100G direct attach cables. Next, we will introduce the difference
between these two types of cables in detail.

 

1.
What is 100G active optic cable?

 

100G
active optic cable refers to the communication cable that needs to use external
energy to convert electrical signals into optical signals or convert optical
signals into electrical signals during the communication process. The optical
transceivers at both ends of the optical cable provide photoelectric conversion
and optical transmission functions, and the transmission rate reaches 100Gb/s.

 

2.
What is 100G direct attach cable?

 

100G
direct attach cable adopts silver-plated conductor and foamed insulated core
wire, which has excellent low attenuation performance and low delay
performance, so that the signal transmission is accurate and precise, and the
transmission speed can be improved. It is a short-distance connection solution
that replaces the optical transceiver. Moreover, the price of this cable is
much cheaper than that of the same type of optical transceivers, and it is
widely welcomed in short-distance connection applications.

 

3.
Structure of 100G AOC active optical cable

 

Simply
put, the active optic cable is composed of two optical transceivers and an
optical cable jumper. The optical fiber transceiver at both ends consists of
OM3 or OM4 multimode fibers of different lengths.

 

4.
Structure of 100G direct attach cable

 

Direct
attach cable is abbreviated as DAC. Its both ends are connected to switches or
servers to realize short-distance transmission. High-speed cables can be
divided into passive direct attach cables and active direct attach cables.
Active direct attach cables has only one more driving chip than passive high
speed cables. The “optical transceivers” on direct attach cables are
not optical transceivers in the true sense. They have no components and can
only transmit electrical signals. Therefore, direct attach cables are cheaper
than other ordinary optical devices. Even if the same port is used as
interfaces of optical transceivers, direct attach cables can also effectively
save costs and reduce power consumption in short-distance applications. This is
the reason why people choose direct attach cables.

 

5.
Classification of 100G AOC active optic cable

 

100G
AOC active optical cable has two types: 100G QSFP28 active optic cable and 100G
QSFP28 to 4X 25G SFP28 active optic cable. The former has an optical
transceiver receiver at both ends to realize one-to-one transmission, and the
latter has a 100G QSFP28 interface at one end, and four 25GSFP28 ports at the
other end, which can provide customers with 100G data transmission.

 

6.
Classification of 100G direct attach cables

 

There
are two types of 100G direct attach cables: 100G QSFP28 DAC and 100G QSFP28 to
25G SFP28 DAC. The former has an optical transceiver receiver at both ends to
realizes one-to-one transmission, and the latter has a 100G QSFP28 at one end
of interface and four 25GSFP28 interfaces at the other end, which can provide
customers with 100G data transmission.

 

It
should be noted here that although the classification of the two is much the
same, the optical transceiver of the active optic cable has a built-in laser,
while there is no laser inside the direct attach cable.