ifSpeed and ASA security context config

yjdabear · ‎12-04-2009

If the "system" context of a multi-context ASA has per-interface config set to a specific speed, say 10Mbit on a 1Gbit interface, I see the interface is reported as 10Mbit in ifSpeed. But does the config only impact the management aspect, or does it throttle the interface down to 10Mbit as well?

Joe Clarke · ‎12-04-2009

If an interface's speed is set to 10 Mbps, then it should only transmit at 10 Mbps. The upstream switch should also negotiate to this speed, and thus the interface will not handle more than 10 Mbps.

yjdabear · ‎12-10-2009

That's odd, because despite this "speed" config, the interface is reportedly achieving 450% utilization, according to SNMP-based tools.

Joe Clarke · ‎12-10-2009

What if you do the calculation manually using the delta values polled from SNMP, and the value of ifSpeed? What is the port speed of the upstr

eam switch? Perhaps the port is really negotiated at a higher speed than what the context is reporting.