Understanding Nexus -- Part 11 -- Port-Channel

Port-Channels provide a mechanism for aggregating multiple physical Ethernet links into a single logical Ethernet link. Port-Channels are typically used to increase availability and bandwidth.

Lets look at some facts of Port-Channel :

• 256 Port-Channels are supported per chassis across all VDCs.
• You can bundle up to 8 ports into a static port channel without using any aggregation protocol.
• Ports have to be “compatible” to operate in a Port-Channel. Use the “show port-channel compatibility-parameters” CLI command for verification (~16 compatibility checks)
• Nexus does not support Port Aggregation Protocol (PAgP) for port channels.
• To use LACP you must enable it.
• Up to 16 links can be configured in a LaCP port channel (Only 8 are “active”)

Creating a L2 Port Channel

To create L2 Port-Channel we will enable LACP first and  then create a port-channel

switch# configure terminal 

switch (config)# feature lacp

switch (config)# interface port-channel 1

The range is from 1 to 4096.

Adding a Layer 2 Port

Now we'll add some L2 interfaces in a created Port-channel

switch# configure terminal 

switch (config)# interface ethernet 1/4

switch(config-if)# switchport

switch(config-if)# channel-group 1

Creating a L3 Port Channel

Sometimes its necessary to create a L3 Port-channel. The configuration is quite same as in IOS, except we have to add "no switchport" command.

switch# configure terminal 

switch (config)# feature lacp

switch(config)# interface port-channel 4

switch(config-if)# ip address 192.0.2.1/8

Adding a Layer 3 Port

switch# configure terminal 

switch (config)# interface ethernet 1/5

switch(config-if)# no switchport

switch(config-if)# channel-group 4

Load Balancing in Port Channels

You can only configure the Load-balancing option in the default VDC.

Port-Channels load balance traffic across all operational links by hashing frame addresses to a numerical value that selects one of the links. You can configure the load-balancing algorithm per “device” or per “module”.

dest-ip-port             Destination IP address and L4 port

dest-ip-port-vlan        Destination IP address, L4 port and VLAN 

destination-ip-vlan      Destination IP address and VLAN 

destination-mac          Destination MAC address

destination-port         Destination L4 port

source-dest-ip-port      Source & Destination IP address and L4 port

source-dest-ip-port-vlan Source & Destination IP address, L4 port and VLAN 

source-dest-ip-vlan      Source & Destination IP address and VLAN(Default for IP)

source-dest-mac          Source & Destination MAC address (Default for Non-IP)

source-dest-port         Source & Destination L4 port

source-ip-port           Source IP address and L4 port

source-ip-port-vlan      Source IP address, L4 port and VLAN 

source-ip-vlan           Source IP address and VLAN 

source-mac               Source MAC address

source-port              Source L4 port