Symptom
The round trip latency between wireless clients and their default gateway is seen to climb to 200+ milliseconds,
and their throughput drops significantly.
Conditions
This is seen with a 9800-80, when using EoGRE tunneled from the controller, to
a WLAN Access Gateway (WAG), that is configured to assign the same IPv4 address
to all clients.
The increase in latency and reduction in throughput is seen when the client count exceeds
1000 - it is not seen when 600 or fewer clients are tunneled.
The scaling problems are not seen when using a WAG that assigns a unique IPv4 address
to each EoGRE client.
Workaround
Use a WAG that assigns a unique IPv4 address to each client, or else
have the APs run in FlexConnect mode, with the EoGRE tunnels
initiated by the AP.
Further Problem Description
