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

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Table of Contents

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)

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

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.

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.

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

Difference Between Link MTU and IP MTU