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
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=12055&t=12052
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