From: Glenn Johnson (GJcomcast@comcast.net)
Date: Fri Aug 01 2003 - 15:37:32 GMT-3
I setup storm control on ports on a 3550 and started hitting those ports
with massive ICMP traffic to see what would happen. While traffic (of
sufficient volume depending upon your configured level) passing THROUGH the
switch is subject to being controlled/dropped, the traffic destined FOR the
switch, e.g., routed port or SVI, does not get 'controlled' (this seems
parallel to regular ACLs not affecting traffic generated by the
switch/router itself) .
However, the results of "show storm control" seem to be misleading. The
message below indicates that the port is "blocking" when it is in fact
forwarding (this is from a high volume of ICMP traffic directed towards an
SVI via a switch port with storm control enabled and set very low).
Cat1#sh storm-control fa0/5 uni
Interface Filter State Level Current
--------- ------------- ------- -------
Fa0/5 Blocking 0.50% 19.24%
Source Router Pings going through (at the same time the switch port is
supposedly "blocking")
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
I get the same "blocking" message when too much traffic (as defined by the
level) is going THROUGH the switch, and that is accurate since I can see the
ICMP traffic on the source router being blocked.
It looks as if the "blocking" designation is simply triggered by an
over-the-level amount of traffic of a certain type, e.g., uni, broad, or
multicast, regardless of the actual blocking status of the port. Or is
there some other way that I should interpret "blocking" ? I'm on
12.1(13)EA1a. Thanks
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