Link Aggregation, Switch Stacking, and HSRP Configuration Guide

Link aggregation combines two or more physical links into a single logical link to increase bandwidth and provide redundancy, which is useful for connecting high‑throughput devices such as core servers.

An example scenario shows two floors of a company network connected via SwitchA and SwitchB, each with VLAN10 and VLAN20, where EtherChannel is used to aggregate three ports on each switch.

Configuration steps (LACP mode):

switch> enable switch# conf t switch(config)# hostname SwitchA SwitchA(config)# interface range g0/0/1-3 SwitchA(config-if-range)# channel-group 1 mode active SwitchA(config-if-range)# interface Port-channel1 SwitchA(config-if)# switchport trunk encapsulation dot1q SwitchA(config-if)# switchport mode trunk

The same commands are applied on SwitchB, replacing the hostname accordingly.

Link redundancy is achieved by providing backup connections, ensuring network stability when a primary link fails.

Switch stacking merges multiple physical switches into a single logical switch using proprietary stacking cables, allowing shared configuration, increased port count, higher aggregate bandwidth, simplified topology, and improved fault tolerance.

Stacking benefits include higher reliability, expanded port capacity, increased uplink bandwidth, simplified network design, and support for long‑distance stacking across multiple floors.

HSRP (Hot Standby Router Protocol) provides router redundancy by creating a virtual router; only one router is active at a time, and a backup takes over if the active router fails, ensuring uninterrupted connectivity.

Examples illustrate traffic failover from an access switch to a backup core switch and the minimal packet loss during the transition.