Port-Pipes; Cr4 Auto-Negotiation - Dell S6100 Configuration Manual

The following table lists the various Layer 2 overheads found in the Dell Networking OS and the number of bytes.
Table 39. Layer 2 Overhead
Layer 2 Overhead
Ethernet (untagged)
VLAN Tag
Untagged Packet with VLAN-Stack Header
Tagged Packet with VLAN-Stack Header
Link MTU and IP MTU considerations for port channels and VLANs are as follows.
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 Link MTU of 1522 and IP MTU of 1500 and untagged members with Link MTU of
1518 and 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.

Port-Pipes

A port pipe is a Dell Networking-specific term for the hardware packet-processing elements that handle network traffic to and from a set of
front-end I/O ports. The physical, front-end I/O ports are referred to as a port-set. In the command-line interface, a port pipe is entered
as port-set port-pipe-number.

CR4 Auto-Negotiation

You can configure interface type as CR4 with auto-negotiation enabled. Many DAC cable link issues are resolved by setting the interface
type as CR4. If the CR4 optic fails to come up, use the autoneg option.
To configure interface type as CR4 with auto-negotiation enabled, use the following commands.
• Set the interface type as CR4 with auto-negotiation enabled.
INTERFACE mode
intf-type cr4 autoneg
To disable CR4 auto-negotiation, use the no intf-type cr4 autoneg command.
• Verify the configuration.
INTERFACE mode
show config
402 Interfaces
Difference Between Link MTU and IP MTU
18 bytes
22 bytes
22 bytes
26 bytes