FW: [c-nsp] 3750 ip direct brioadcast

[Brian Turnbow]

 sorry didn't hit reply to all

-----Original Message-----
From: Brian Turnbow 
Sent: mercoledì 14 settembre 2005 18.56
To: 'Oliver Boehmer (oboehmer)'
Subject: RE: [c-nsp] 3750 ip direct brioadcast 

Replying from the address it came in on is ok, but why is it responding to a broadcast address with direct broadcast disabled accross the box?
Doesn't direct broadcast disabled cause packets to a known Ip broadcast address to be dropped altogether when recieved from an interface not connected to that subnet? Or is it just not forwarded out of the port?

Brian 

-----Original Message-----
From: Oliver Boehmer (oboehmer) [mailto:oboehmer at cisco.com] 
Sent: mercoledì 14 settembre 2005 18.38
To: Brian Turnbow
Subject: RE: [c-nsp] 3750 ip direct brioadcast 

why shouldn't it reply with the address of the interface the ping came in from?

	oli

Brian Turnbow <> wrote on Wednesday, September 14, 2005 6:34 PM:

> Sorry the last part should be
> 
> 
> A ping gets sent to 192.168.0.255 (FE1/0/1 broadcast address), and
> the router responds from the 10.1.1.1 address with an echo reply. 
> 
> 
> 
> 
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Brian Turnbow 
> Sent: mercoledì 14 settembre 2005 18.23
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] 3750 ip direct brioadcast
> 
> 
> 
> Hello all,
> I have a couple of 3750s image on the boxes is 12.2(20)SE1 trunked
> back 
> on to the network all done with static routing.
> So I have int vlan 82 with an IP address and some ports set up as L3
> ports with an IP address.
> All interfaces have ip direct broadcast disabled , and doing a show ip
> int xxx I can see
> Directed broadcast forwarding is disabled
> On all interfaces (even vlan interface)
> But the switch responds (from the vlan interface) to the FE ports
> broadcast address.
> 
> So basically I have
> Int vlan 82
> Ip address 10.1.1.1 255.255.255.0
> 
> And
> Int fast 1/0/1
> Ip address 192.168.0.1 255.255.255.0
> 
> 
> A ping gets sent to 192.168.1.255 , and the router responds from the
> 10.1.1.1 address with an echo reply.
> 
> Anyone else seen this or have any ideas ?
> 
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