Campus lan and Wireless lan solution Design Guide

Multigigabit Ethernet (mGig) and PoE at the access-layer 
As customers migrate to 802.11ax (Wi-Fi 6), the access layer switch platforms to which the Catalyst 9100 
Series APs connect may also need to be upgraded. Data rates above 1 Gbps, supported by 802.11ax (Wi-Fi 6) 
APs, are driving the requirement for mGig port speeds (2.5 Gbps and 5 Gbps) at the access layer. The higher 
MIMO rates of these APs, along with the rapid adoption of IoT devices is also driving the requirement for higher 
PoE requirements (PoE+, Cisco UPOE / 802.3bt Type 3, and Cisco UPOE+ / 802.3bt Type 4) at the access layer 
switch ports.
Oversubscription ratios 
The migration to mGig may also require increasing uplink port speeds in order to maintain the desired 
oversubscription ratio. Determining the oversubscription ratio of the uplink when deploying mGig technology can 
be more challenging than traditional switches with only 1 Gbps ports. You need to take into consideration the 
number of access ports on the switch which support mGig, since not all switches support mGig on all ports.
You also need to take into consideration the speeds at which the mGig port is capable of operating, as well as 

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the speed at which the port will be operating. Although an mGig switch port may be capable of operating at 10 
Gbps, Cisco Catalyst 9100 Series APs only operate at mGig speeds up to 5 Gbps currently. 
For example, let’s say you deploy a 48-port switch which supports mGig up to 10 Gbps on 12 access ports, 1 
Gbps on the other 36 ports, and with 4x10 Gbps fixed uplinks. However, you only provision two 10 Gbps 
uplinks. This configuration would provide up to 20 Gbps uplink bandwidth, assuming all uplinks are active – as 
in a Multichassis EtherChannel (MEC) configuration.