From: Vladimir Sousa (vladrac@gmail.com)
Date: Thu Nov 15 2007 - 15:31:37 ART
Hello Sean,
Just one question, what makes the broadcast segmentation? the vlan or the
ip?
if you set 2 ports in vlan 1, will it receive traffic for vlan 1 in both
IPs?
If you take 2 routers and connect to these 2 ports, and you enable the same
pair of IP, Sec IP, will they receive the broadcast packets for each subnet?
will they respond in both cases?
I think the answer to your question is, yes, packets will be delivered to
both ports, but will be responded by the hosts configured on the same subnet
IP.
Vlad
On 11/15/07, Sean C <upp_and_upp@hotmail.com> wrote:
>
> Hi Group,
>
> If I have a 3550 with Vlan 1:
>
> int vlan 1
> ip address 10.1.1.254 255.255.255.0
> ip address 10.1.2.254 255.255.255.0 secondary
>
> Interface f0/1 is in Vlan1 and has a host connected (host1) with IP
> 10.1.1.1
> /24
> Interface f0/2 is also in Vlan1 and has a host connected (host2) with IP
> 10.1.2.1 /24
>
> If host1 sends a local broadcast (10.1.1.255), will host2 receive this
> since
> both IP subnets are in the same layer 2 segment?
>
> This leads me into other areas, like what if it's an IP broadcast
> (255.255.255.255) or layer 2 broadcast (f.f.f) or if host2 is across a
> couple
> of 3550s, with each switch's SVI in both IP subnets. I'm thinking that
> host2
> will receive the frame (what host2 does with the frame is a different
> story).
> I'm just curious to see how the packets are switched.
>
> I looked pretty hard on-line, but can't find a definitive answer. Here's
> some
> things I found for guidance (buyer beware):
> http://www.groupstudy.com/archives/cisco/199912/msg00535.html
>
> http://books.google.com/books?id=77h9SA94kasC&pg=PA53&lpg=PA53&dq=%22secondar
>
> y+address%22+broadcast+interface&source=web&ots=ZK2MDq5iey&sig=niwz8-D79xoTWM
> Jt97wCCinJfcQ
> http://tcpmag.com/forums/forum_posts.asp?tid=1383&pn=10
>
> Even found a decent post from Howard Berkowitz (I miss his posts):
> http://www.groupstudy.com/archives/cisco/200306/msg01434.html
>
> I don't have immediate access to a LAN sniffer or I'd bang on this myself.
> Curious to hear the group's thoughts. Thanks in advance,
> Sean C. CCIE #17085
>
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