Users Guide

634 Port Characteristics
a VLAN header) to 9216 bytes. Dell EMC Networking N-Series switches
assumes that all packets are in Ethernet format. Any device connecting to the
same broadcast domain must support the same MTU.
Dell EMC Networking N-Series switches do not fragment L2 or L3 forwarded
traffic. Received frames larger than the system MTU are discarded. The
switch will not transmit a frame larger than the system MTU.
Packets originated by the switch are fragmented based upon path MTU
discovery. IPv4 packets forwarded in software are dropped if they exceed the
IPv4 MTU of the outgoing interface, whether or not the Do Not Fragment bit
is set in the IP header. An ICMP Fragmentation Needed message is returned
to the sender. Dell EMC Networking IPv4 software forwarding does not
fragment packets.
An IPv4 packet originated on the switch is fragmented in the IP stack if it is
larger than the IPv4 path MTU to the packet’s destination. For each IPv4
route in the IP stack’s routing table, the default IPv4 path MTU is the IPv4
MTU of the outgoing interface. The IP stack updates the path MTU for each
route when it receives Fragmentation Needed ICMP messages.
An IPv6 packet originated on the switch is fragmented in the IP stack if it is
larger than the IPv6 path MTU to the packet’s destination. IPv6 does not
allow forwarded packets to be fragmented. If a forwarded IPv6 packet is larger
than the path MTU to its destination, the packet is dropped and an ICMPv6
Packet Too Big message is returned.
What is Link Dependency?
The link dependency feature provides the ability to enable or disable one or
more ports based on the link state of one or more different ports. With link
dependency enabled on a port, the link state of that port is dependent on the
link state of another port. For example, if port A is dependent on port B and
the switch detects a link loss on port B, the switch automatically brings down
the link on port A. When the link is restored to port B, the switch
automatically restores the link to port A.
A maximum of 72 dependency groups can be created. The ports participating
in the Link Dependency can be across all the Stack Units (Manager/Member
unit).