[c-nsp] VS broadcast address relaying from Vlan to Vlan

[Church, Charles]

Arne,

	By forwarding broadcasts from one VLAN to another, aren't you
exceeding that 32 device/VLAN rule?  Do all devices need to contact all
other devices?  If not, you might be able to be creative with private
VLANs.  I'd hit up the vendor first though, to see how they recommend
more than 32 devices, if you need any to any connectivity. 

Chuck

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Arne Larsen /
Region Nordjylland
Sent: Monday, March 10, 2008 11:47 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] VS broadcast address relaying from Vlan to Vlan


Hi Folks.

I hope someone can help me out here. I have a problem with devices from
a supplier to our ventilation system.
There units are IP based, but they aren't very clever units. When the
temperature is being propagated to all units the sending device sends it
to the broadcast address on its own LAN.
Furthermore the devices are sending information to each other the same
way, by sending to the broadcast address.
So as long all devices is on the same broadcast domain everything works
fine. The units sends to port 49152 udp on the broadcast address.
But, there can only be 32 units on each broadcast domain for some reason
that I'm not aware off.
So I have to segment it into more VLan on our core switch (its 6500).
Now, how do I propagate the packets that are sent to a broadcast address
on one VLan to all others VLan.
I've setup helper-addresses for relaying the broadcast traffic to the
broadcast address on all others VLan and I've appended port 49152 udp in
the forward-protocol.

Here is the what I've tried to get working, but it's not.


interface Vlan400
 ip address 10.8.40.1 255.255.255.192
 ip broadcast-address 10.8.40.63
ip helper-address 10.2.40.127
 ip helper-address 10.2.40.191
 ip directed-broadcast

interface Vlan401
 ip address 10.8.40.65 255.255.255.192
 ip broadcast-address 10.8.40.127
 ip helper-address 10.2.40.191
 ip helper-address 10.2.40.63
 ip directed-broadcast
!
interface Vlan402
 ip address 10.8.40.129 255.255.255.192
 ip broadcast-address 10.8.40.191
 ip helper-address 10.2.40.63
 ip helper-address 10.2.40.127
 ip directed-broadcast




/Arne

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