Sge2000 and srw2024 help.

[darrenpearce]

Hi

We are a BMS company working on a big project, We have decided to install a large network which involve 6x SGE2000 models in standalone mode with one set as a layer 3, also about 25 SRW2024 connected to each other and to the SGE2000 all with fibre.

We have split the network into different Vlans as we have over 500 devices some on different networks. We are using one of the SGE2000 set in layer 3 mode to pass information between Vlans, This all works fine.

The problem we have is we need to use a piece of software which I have attached, This would normally search for the Trend controllers which we use and bring back information i.e. name, IP address, Subnet, Default gateway, LAN no, Outstation No and lots more info regardless of what network they was on. Now I have Vlans set i.e. Vlan 1 to 10 If I am connected to vlan 1 and then run the software it will show me all the trend devices on that VLan but it cannot talk across the vlan which I need it to do. Is there  a way I can do this by changing something in the switch or do I have to plug into each vlan separately which would be a problem?

Your help would be most welcome

Regards

Darren P
Commissioning Engineer

[David Hornstein]

Hi Darren,

I figured why the trend discovery tool doesn't work between VLANs.

Check the attached wireshark screen capture.

You will note that the packet sent to discover devices is a broadcast packet, with a destination IP address of 255.255.255.255.  That is one of the beauties of VLANs and Layer 2 segmentation, broadcast storms or even broadcast packets are not propogated to other vlans.

This is your issue, that broadcast discovery packet will only stay in the VLAN the discovering PC is in.

Luckily the SGE2000 and SRW2024 are pretty good switches.  I'm thinking there maybe a way around this, i would like you to directly contact me at my email address; dhornste@cisco.com, I want to run something by you.

Include your phone number and country code.

regards Dave