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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 channels MTU values cannot be higher than 2100 for link MTU or 2000 bytes for
IP MTU.
VLANs:
All members of a VLAN must have 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 Link MTU
of 1522 and IP MTU of 1500 and untagged members with Link MTU of 1518 and IP MTU of 1500. The
VLANs Link MTU cannot be higher than 1518 bytes and its IP MTU cannot be higher than 1500 bytes.
The following shows the difference between Link MTU and IP MTU.
Layer 2
Overhead
Link MTU and IP MTU Delta
Ethernet
(untagged)
18 bytes
VLAN Tag 22 bytes
Untagged Packet
with VLAN-Stack
Header
22 bytes
Tagged Packet
with VLAN-Stack
Header
26 bytes
negotiation auto
Enable auto-negotiation on an interface.
Syntax
negotiation auto
To disable auto-negotiation, enter no negotiation auto command.
Defaults Enabled.
Command Modes INTERFACE
Supported Modes All Modes
Command
History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.4(0.0) Supported on the FN I/O Aggregator.
Usage
Information
The no negotiation auto command is only available if you first manually set the speed of a port to
10Mbits or 100Mbits.
Example
(Configured)
Dell#show interfaces configured
TenGigabitEthernet 0/1 is up, line protocol is up
Hardware is DellEth, address is 00:1e:c9:de:04:9c
Current address is 00:1e:c9:de:04:9c
Server Port AdminState is N/A
Pluggable media not present
Interface index is 33886978
Internet address is not set
Mode of IPv4 Address Assignment : NONE
DHCP Client-ID :001ec9de049c
Interfaces 497