It is monitoring other ports. I did the three steps: enable the feature,
configure the monitor port, and configure the monitored port. It is seeing
traffic, but not multicasts.
It seems to disable unknown unicast and unregistered multicasts on the
monitor port no matter what you do. I have decided that it's to protect the
user from trouble. If you turned this feature on while the monitor port was
connected to something more than just an analyzer, you could cause problems
(even loops?)
Priscilla
At 10:53 PM 7/11/01, Marty Adkins wrote:
>Priscilla Oppenheimer wrote:
> >
> > Has anyone seen this and is there a workaround?
> >
> > On a Catalyst 1900 switch enterprise edition, the software has decided
that
> > one of my ports should not flood unknown unicast or multicast. This
> > wouldn't be a problem except that the port is also my monitor port for
> > sniffing packets, and I WANT to see unknown unicast and multicast. I'm
> > trying to see EIGRP, CDP, etc. from a router connected to another port.
The
> > monitoring is working, but I'm not seeing multicasts.
> >
> > SwitchA#show int e 0/1
> > Hardware is Built-in 10Base-T
> > Address is 00B0.6426.7941
> > MTU 1500 bytes, BW 10000 Kbits
> > 802.1d STP State: Forwarding Forward Transitions: 1
> > Unknown unicast flooding: Disabled
> > Unregistered multicast flooding: Disabled
> > Duplex setting: Half duplex
> > Back pressure: Disabled
> >
> > See how it says that unknown unicast and unregistered multicast are
> > disabled? It doesn't say that for any of the other ports.
> [snip]
>
>Priscilla,
>This is apparently an intentional side effect of enabling a port for
>SPAN/port monitoring, according to:
>http://www.cisco.com/univercd/cc/td/doc/product/lan/28201900/1928v8x/19icg8x/19icweb.htm#xtocid482036
>So your analyzer would get only broadcasts until you configure it to
>monitor (copy) other ports on the switch. Those other ports will be
>getting unknowns and multicast so your monitor port will see a copy.
>
>I agree that this behavior is different than all the other Cisco switches
>including XLs, 4xxx, 5xxx, and 6xxx.
>
>- Marty
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=12159&t=12052
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