Cisco Trunking and Port Channeling Implementation | Cisco Load Balancing

Port Channeling

Introduction

Port Channels refer to the aggregation of multiple physical interfaces into one logical interface to provide higher aggregated bandwidth, load balancing, and link redundancy. Port Channel scan connect to interfaces across switching modules, so a failure of a switching module cannot bring down the Port Channel link.

Port Channel

About Port Channeling and Trunking

Trunking is a commonly used storage industry term. However, the Cisco NX-OS software and switches in the Cisco MDS 9000 Family implement trunking and Port Channeling as follows:

• Port Channeling enables several physical links to be combined into one aggregated logical link.

Trunking

Port channeling and Trunking

• Trunking enables a link transmitting frames in the EISL format to carry (trunk) multiple VSAN traffic. For example, when trunking is operational on an E port, that E port becomes a TE port.

• Port Channeling—Interfaces can be channeled between the following sets of ports:

– E ports and TE ports

– F ports and NP ports

– TF ports and TNP ports

• Trunking—Trunking permits carrying traffic on multiple VSANs between switches. See the Cisco MDS 9000 Family NX-OS Fabric Configuration Guide.

• Both Port Channeling and trunking can be used between TE ports over EISLs.

About Port Channel Modes

There are two types of Port channel modes.

1. ON (Default)

2. Active

Differences between ON and Active modes

Restrictions

Cisco MDS 9000 Family switches support the following number of Port Channels per switch:

• Switches with only Generation 1 switching modules do not support F and TF Port Channels.

• Switches with Generation 1 switching modules, or a combination of Generation 1 and Generation 2 switching modules, support a maximum of 128 Port Channels. Only Generation 2 ports can be included in the Port Channels.

• Switches with only Generation 2 switching modules or Generation 2 and Generation 3 modules support a maximum of 256 Port Channels with 16 interfaces per Port Channel.

• A Port Channel number refers to the unique identifier for each channel group. This number ranges from of 1 to 256.

Port Channel Configuration

Port Channels are created with default values. You can change the default configuration just like any other physical interface.

Port Channel Configurations

About Port Channel Configuration

Before configuring a Port Channel, consider the following guidelines:

• Configure the Port Channel across switching modules to implement redundancy on switching module reboots or upgrades.

• Ensure that one Port Channel is not connected to different sets of switches. Port Channels require point-to-point connections between the same set of switches.

If you misconfigure Port Channels, you may receive a misconfiguration message. If you receive this message, the Port Channel’s physical links are disabled because an error has been detected.

A Port Channel error is detected if the following requirements are not met:

• Each switch on either side of a Port Channel must be connected to the same number of interfaces.

• Each interface must be connected to a corresponding interface on the other side.

• Links in a Port Channel cannot be changed after the Port Channel is configured. If you change the links after the Port Channel is configured, be sure to reconnect the links to interfaces within the Port Channel and re enable the links.

If all three conditions are not met, the faulty link is disabled.

Enter the show interface command for that interface to verify that the Port Channel is functioning as required.

Creating a Port Channel

1. Enters configuration mode.

Switch # config t

2. Configures the specified Port Channel (1) using the default ON mode.

Switch (config) # interface port-channel 1

3. Configures the ACTIVE mode.

Switch (config-if) # channel mode active

4. Reverts to the default ON mode.

Switch (config-if) # no channel mode active

5. Deletes the specified Port Channel (1), its associated interface mappings, and the hardware associations for this Port Channel.

Switch (config) # no interface port-channel 1

Port-channel 1 deleted and all its members disabled please do the same operation on the switch at the other end of the port-channel

You can add or remove a physical interface (or a range of interfaces) to an existing Port Channel.

The compatible parameters on the configuration are mapped to the Port Channel. Adding an interface to a Port Channel increases the channel size and bandwidth of the Port Channel.

Removing an interface from a Port Channel decreases the channel size and bandwidth of the Port Channel.

You can add a physical interface (or a range of interfaces) to an existing Port Channel. The compatible parameters on the configuration are mapped to the Port Channel. Adding an interface to a Port Channel increases the channel size and bandwidth of the Port Channel.

A port can be configured as a member of a static Port Channel only if the following configurations are the same in the port and the Port Channel:

Speed

Mode

Rate mode

Port VSAN

Trunking mode

Allowed VSAN list or VF-ID list

Compatibility Check

A compatibility check ensures that the same parameter settings are used in all physical ports in the channel. Otherwise, they cannot become part of a Port Channel. The compatibility check is performed before a port is added to the Port Channel.

The check ensures that the following parameters and settings match at both ends of a Port Channel:

• Capability parameters (type of interface, Gigabit Ethernet at both ends, or Fibre Channel at both ends).

• Administrative compatibility parameters (speed, mode, rate mode, port VSAN, allowed VSAN list, and port security).

To add an interface to a Port Channel, follow these steps:

1. Configures the specified port interface (fc1/15).

Switch (config) # interface fc1/15

2. Adds physical Fibre Channel port 1/15 to channel group 15. If channel group 15 does not exist, it is created. The port is shut down.

Switch (config-if) # channel-group 15

To add a range of ports to a Port Channel, follow these steps:

1. Configures the specified range of interfaces. In this example, interfaces from 1/1 to 1/5 are configured.

Switch (config) # interface fc1/1 – 5

2. Adds physical interfaces 1/1, 1/2, 1/3, 1/4, and 1/5 to channel group 2. If channel group2 does not exist, it is created.

If the compatibility check is successful, the interfaces are operational and the corresponding states apply to these interfaces.

Switch (config-if) # channel-group 2

3. Deletes the physical Fibre Channel interfaces in channel group 2.

Switch (config-if) # no channel-group 2

Enabling and Configuring Auto creation

1. Enters the configuration mode for the selected interface(s).

Switch (config) # interface fc8/13

2. Automatically creates the channel group for the selected interface(s).

Switch (config- if) # channel-group auto

3. Disables the auto creation of channel groups for this interface, even if the system default configuration may have auto creation enabled.

Switch (config- if) # no channel-group auto

Some useful commands

Displays the Port Channel Summary

Switch # show port-channel summary

---------------------------------------------------------------- Interface Total Ports Oper Ports First Oper Port

---------------------------------------------------------------- port-channel 77 2 0 --

port-channel 78 2 0 --

port-channel 79 2 2 fcip200

Displays the Port Channel Configured in the Default ON Mode

Switch # show port-channel database

port-channel 77

Administrative channel mode is on

Operational channel mode is on

Last membership update succeeded

2 ports in total, 0 ports up

Ports: fcip1 [down]

fcip2 [down]

port-channel 78

Administrative channel mode is on

Operational channel mode is on

Last membership update succeeded

2 ports in total, 0 ports up

Ports: fc2/1 [down]

fc2/5 [down]

port-channel 79

Administrative channel mode is on

Operational channel mode is on

Last membership update succeeded

First operational port is fcip200

2 ports in total, 2 ports up

Ports: fcip101 [up]

fcip200 [up] *

Displays the Port Channel Configured in the ACTIVE Mode

port-channel 77

Administrative channel mode is active

Operational channel mode is active

Last membership update succeeded

2 ports in total, 0 ports up

Ports: fcip1 [down]

fcip2 [down]

port-channel 78

Administrative channel mode is active

Operational channel mode is active

Last membership update succeeded

2 ports in total, 0 ports up

Ports: fc2/1 [down]

fc2/5 [down]

port-channel 79

Administrative channel mode is active

Operational channel mode is active

Last membership update succeeded

First operational port is fcip200

2 ports in total, 2 ports up

Ports: fcip101 [up]

fcip200 [up] *

Displays the Consistency Status without Details

Switch # show port-channel consistency

Database is consistent

Displays the Consistency Status with Details

Switch # show port-channel consistency detail

Displays the Port Channel Usage

Switch # show port-channel usage

Displays the Port Channel Compatibility

Switch # show port-channel compatibility-parameters

Displays Auto created Port Channels

Switch # show interface fc1/1

Displays the Specified Port Channel Interface

Switch # show port-channel database interface port-channel 128

Displays the Port Channel Summary

Switch # show port-channel summary