Basic function principles

Store and Forward

The switch operates according to the store-and-forward principle. Frames that are faulty (CRC error), too short (< 64 bytes) or too long (> 1536 bytes) are generally not passed on.

Address Memory

The switch learns the MAC addresses of the connected devices for each port. Only frames that have these addresses, broadcast/or multi-cast addresses, or which have unknown addresses are passed on to this port. Because the switch remembers more than 1000 addresses for each port, it is also suitable for connecting entire network segments. After approx. 5 minutes (Aging Time) unused addresses are removed from the memory – if required, they are re-learnt again later.

Throughput

The switch can pass through up to 148800 Ethernet frames per second (Wire Speed).

PoE - Power over Ethernet

The CU20xx, CU22xx and CU26xx switches do not support PoE according to IEEE 802.3; they do not reveal themselves as PSE (power sourcing equipment) or PD (powered devices). Any PSE connected to the switch must therefore not apply a voltage.
No provision is made in the standard for passive interconnection or distribution.

Jumbo Frames

Jumbo Frames are oversized Ethernet telegrams with a length of more than 1518 bytes. They are used in applications that require very high data throughput, for example.

The CU2208 (from hardware version 01) supports Jumbo Frames up to 9720 bytes on all ports. Please note the following:

• Jumbo Frames only supported by ports with Gbit link
• Jumbo Frames place high demands on internal data transmission. It is therefore necessary to assess the data throughput that can be achieved through the CU2208 for each individual application. Under full load no more than 2 ports can be used for Jumbo Frames at the same time.

Jumbo Frames are not subject to standardization. It is therefore necessary to verify that the frames used by the application are supported by the CU2208.