Reference Guide

Port Channels:
• All members must have the same link MTU value and the same IP MTU value.
• The port channel link MTU and IP MTU must be less than or equal to the link MTU and IP MTU values
configured on the channel members.
For example, if the members have a link MTU of 2100 and an IP MTU 2000, the port channel’s MTU
values cannot be higher than 2100 for link MTU or 2000 bytes for IP MTU.
VLANs:
• All members of a VLAN must have the same IP MTU value.
• Members can have different link MTU values. Tagged members must have a link MTU 4 bytes higher
than untagged members to account for the packet tag.
• The VLAN link MTU and IP MTU must be less than or equal to the link MTU and IP MTU values
configured on the VLAN members.
For example, the VLAN contains tagged members with a link MTU of 1522 and an IP MTU of 1500 and
untagged members with a link MTU of 1518 and an IP MTU of 1500. The VLAN’s Link MTU cannot be
higher than 1518 bytes and its IP MTU cannot be higher than 1500 bytes.
Auto-Negotiation on Ethernet Interfaces
Setting Speed and Duplex Mode of Ethernet Interfaces
By default, auto-negotiation of speed and duplex mode is enabled on 1GbE and 10GbE Ethernet
interfaces on an Aggregator.
The local interface and the directly connected remote interface must have the same setting. Auto-
negotiation is the easiest way to accomplish these settings, as long as the remote interface is capable of
auto-negotiation.
NOTE: As a best practice, Dell Networking recommends keeping auto-negotiation enabled. Auto-
negotiation should only be disabled on switch ports that attach to devices not capable of
supporting negotiation or where connectivity issues arise from interoperability issues.
For 100/1000/10000 Ethernet interfaces, the negotiation auto command is tied to the speed command.
Auto-negotiation is always enabled when the speed command is set to 1000 or auto. In Dell Networking
OS, the speed 1000 command is an exact equivalent of speed auto 1000 in IOS.
To discover whether the remote and local interface require manual speed synchronization, and to
manually synchronize them if necessary, follow these steps.
Step Task Command Syntax Command Mode
1.
Determine the local interface status. show interfaces [interface] status EXEC Privilege
2.
Determine the remote interface
status.
[Use the command on the remote
system that is equivalent to the
above command.]
EXEC
EXEC Privilege
3.
Access CONFIGURATION mode. config EXEC Privilege
Interfaces
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