From: san (san.study@gmail.com)
Date: Fri Dec 09 2005 - 15:02:23 GMT-3
How can i trigger a unknown unicast DMAC packet ?
/SAN
On 12/8/05, Brian Dennis <bdennis@internetworkexpert.com> wrote:
> The command is used to stop the switch from forwarding unicast packets
> with an unknown destination MAC address out a port. It's not used to
> stop all unicast traffic from being sent out a port.
>
> Here is an example:
>
> R1 (10.1.1.1) and R2 (10.1.1.2) are connected to ports Fa0/1 and Fa0/2
> on the switch. The switch is configured with "switchport block unicast"
> on Fa0/1 and Fa0/2.
>
> Switch#clear mac-address-table dynamic
> Switch#sho mac-address-table int fa0/1
> Mac Address Table
> -------------------------------------------
>
> Vlan Mac Address Type Ports
> ---- ----------- -------- -----
> Switch#sho mac-address-table int fa0/2
> Mac Address Table
> -------------------------------------------
>
> Vlan Mac Address Type Ports
> ---- ----------- -------- -----
> Switch#
>
>
> R2#ping 10.1.1.1
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
> .....
> Success rate is 0 percent (0/5)
> R2#clear arp
> R2#ping 10.1.1.1
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
> ...!!
> Success rate is 40 percent (2/5), round-trip min/avg/max = 1/2/4 ms
> R2#
>
>
> Switch#sho mac-address-table int fa0/1
> Mac Address Table
> -------------------------------------------
>
> Vlan Mac Address Type Ports
> ---- ----------- -------- -----
> 1 0030.9410.4820 DYNAMIC Fa0/1
> Total Mac Addresses for this criterion: 1
> Switch#sho mac-address-table int fa0/2
> Mac Address Table
> -------------------------------------------
>
> Vlan Mac Address Type Ports
> ---- ----------- -------- -----
> 1 0003.e38e.6140 DYNAMIC Fa0/2
> Total Mac Addresses for this criterion: 1
> Switch#
>
>
> HTH,
>
> Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> bdennis@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Direct: 775-745-6404 (Outside the US and Canada)
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> san
> Sent: Thursday, December 08, 2005 10:47 PM
> To: lab
> Subject: switchport block question
>
> Could not understand, what does "switchport block unicast" does ?
> How to test/verify this behaviour ?
>
> Router3(F0/0)---------F0/3-Switch-F0/5--------F0/0Router5
>
> Question:
> If enabled on F0/3, Does it block unicast traffic from R3 to R5 or
> R5 to R3 ?
>
> I tried pinging from R3 & its successful.
>
>
> http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/12_2_25a/con
> f/uniflood.htm
>
>
> Thanks
> SAN
>
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