CCNP Enterprise Core (350-401)

LACP interface priority enables the master switch to choose which member interfaces are active in a port channel when there are more member interfaces than the maximum permitted. A port with a lower priority number is preferred. The interface priority can be set in interface configuration mode, with the command lacp port-priority 1

The LACP system priority identifies the master switch for a port channel. The master switch is responsible for choosing the interfaces that are active in a port channel, and if there are more than the maximum number configured which interfaces are disabled. The system with the lower system priority is preferred. The system priority can…

An etherchannel can be configured to have a specific maximum number of interfaces. A scenario where this can be useful is ensure the active member count is within the powers of two. (2 links, 4 links, 8 links) for load balancing algorithm purposes. To set the maximum number of member interfaces in a port-channel, configure…

An etherchannel typically comes online when only one member interface can successfully form an adjacency with a remote device. In some network design scenarios there may be a situation where a single member interface won’t provide enough bandwidth to serve traffic effectively. A minimum number of member interfaces to be established can be set in…

The original LCP standards sent out a LACP protocol packet every 30 seconds; if a LACP packet is not received three times then the link is deemed unusable. This may result in up to a 90 second delay before a problematic link is removed from the port channel. An amendment was made to the standards…

show etherchannel port show etherchannel port can display detailed information on the local configuration and information from the packets received. This in some cases can provide too much information and slow down the network administrators troubleshooting efforts. Commands exist to be more specific in troubleshooting efforts. show lacp neighbor show lacp neighbor with the optional…

Once a port channel has established, it is important to check that it is operating optimally. The command show etherchannel summary provides a summary of configured port channels on the switch along with its status. Status Code Description U The Etherchannel is up and working correctly D The Etherchannel is down and not working M…

Etherchannel is configured in the interface configuration mode of the switch. There are three ways that it can be configured: statically, LACP, or PAgP. X in the examples below are the channel-group number. Statically channel-group X mode on LACP Etherchannel Active Mode channel-group X mode active Passive Mode channel-group X mode passive PAgP Etherchannel Desirable…

Etherchannel allows a method of doubling (or more) bandwidth between switches without spanning tree protocol (STP) blocking one of the links. Multiple physical links to be grouped into a single logical link, called an Etherchannel or port channel as defined in the 802.3AD link aggregation specification. The multiple physical links that form the logical link…

The most common method of establishing a trunk port is statically setting it in the configuration using switchport mode trunk. Cisco does provide a method where the port can be negotiated as a trunk automatically with Dynamic Trunking Protocol (DTP) Dynamic trunk ports are established by the switch by sending DTP packets across the link…