Hi,
I am glad that this topic is discussed here. In fact currently I am doing
a project that is trying to make use of the Port Monitoring/SPAN
feature as a form of keepalive & duplicate traffic discovery
with a third party product. I won't go into that detail.
I had read the portion of info at the directed web link. But would like to
confirm my doubts. I need all the valuable advise and inputs from all of
you.
May be I am poor in my English to interpret this. Appreciate to confirm,
does that mean all Cisco Switches, be it Cat 19xx, 29xx, 5xxx, 6xxx, etc
have the similar feature of blocking Unknow Unicast & Unregistered Multicast
from forwarding through the Source port & not reaching the destination
directed ports?
The traffic is also not forwarded out of the connected port to the connected
neighbouring
port?
Source Switch Port1------------Router---------WAN
| ^
Mirrored Traffic------->| |
| Eth
Destine Switch Port2
Based on the above diagram for simple discussion.
Does that means EIGRP routing entries will be discarded at the Switch Port1
& not updated to the Router
Ethernet port? Similar CDP, Multicast Video streaming, Mainframe
application, ...etc, will not able
to pass through the Monitored port?
Lastly, is there a way to enable all traffic to flow through the Monitored
switch port?
Hope to hear some comments on this. Apprecaite the inputs.
Cheers.
regard
Steven Quek
-----Original Message-----
From: Marty Adkins [mailto:[EMAIL PROTECTED]]
Sent: Thursday, July 12, 2001 11:09 AM
To: [EMAIL PROTECTED]
Subject: Re: port block unicast and multicast [7:12052]
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=12096&t=12052
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