Configuration manual

• The 40G port is lost in the configuration when the port is split; be sure the port is also removed from
other L2/L3 feature configurations.
• The system must be reloaded after issuing the CLI for the change to take effect.
Configure the MTU Size on an Interface
The link MTU is the frame size of a packet. The IP MTU size is used for IP fragmentation.
If the system determines that the IP packet must be fragmented as it leaves the interface, the system
divides the packet into fragments no bigger than the size set in the ip mtu command.
In the Dell Networking OS, MTU is defined as the entire Ethernet packet (Ethernet header + FCS +
payload).
Because different networking vendors define MTU differently, check their documentation when planning
MTU sizes across a network.
The following table lists the various Layer 2 overheads found in the Dell Networking OS and the number
of bytes.
Table 24. Layer 2 Overhead
Transmission Media MTU Range (in bytes)
Ethernet
594-12000 = link MTU
576-11982 = IP MTU
Converting a QSFP or QSFP+ Port to an SFP or SFP+ Port
You can convert a QSFP or QSFP+ port to an SFP or SFP+ port using the Quad to Small Form Factor
Pluggable Adapter (QSA).
QSA provides smooth connectivity between devices that use Quad Lane Ports (such as the 40 Gigabit
Ethernet adapters) and 10 Gigabit hardware that uses SFP+ based cabling. Using this adapter, you can
effectively use a QSFP or QSFP+ module to connect to a lower-end switch or server that uses an SFP or
SFP+ based module.
When connected to a QSFP or QSFP+ port on a 40 Gigabit adapter, QSA acts as an interface for the SFP
or SFP+ cables. This interface enables you to directly plug in an SFP or SFP+ cable originating at a 10
Gigabit Ethernet port on a switch or server.
You can use QSFP optical cables (without a QSA) to split a 40 Gigabit port on a switch or a server into
four 10 Gigabit ports. You must enable the fan-out mode in order for this mechanism to work.
Similarly, you can enable the fan-out mode to configure the QSFP port on a device to act as an SFP or
SFP+ port. As the QSA enables a QSFP or QSFP+ port to be used as an SFP or SFP+ port, Dell Networking
OS does not immediately detect the QSA after you insert it into a QSFP port cage.
After you insert an SFP or SFP+ cable into a QSA connected to a 40 Gigabit port, Dell Networking OS
assumes that all the four fanned-out 10 Gigabit ports have plugged-in SFP or SFP+ optical cables.
However, the link UP event happens only for the first 10 Gigabit port and you can use only that port for
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Interfaces