3Com 5500G-EI [WOL / broadcast over subnets]

[stwger]

Hello all,

after trying and googling a lot I decided to open a new thread about my problem.

We have a 3Com 5500G-EI Stack (4x L3-Switches) with one VLAN-Interface. (homed in 5 different subnets)

The problem is:
- we try to wake up clients via WOL in different subnets with SCCM2007
- SCCM sends subnet-directed broadcasts (e.g. 192.168.10.255 for subnet 192.168.10.0/24)

I think here must be the problem

I googled and found that ip forward-broadcast has to be enabled for the system and the corresponding VLAN-interface.
-> enabling this function didn't work for our scenario.
-> this command should convert sn-directed-broadcast into broadcasts to 255.255.255.255?? (L2)


Sniffing on the destination machine gave the following results:
- subnet-directed broadcasts are only received if the sending computer is in the same subnet.
- a broadcast to 255.255.255.255 is received over different subnets

-> SCCM has no option to send packets to 255.255.255.255


Configuration / already working:
- all clients are already configured correctly and can be woke up with a pc in their subnet (using sn-directed broadcasts)
- all clients can be woke up by sending the magic packet with an extra tool to 255.255.255.255 (it doesn't matter in which subnets they are)

I hope someone can help me to fix this problem.

Thanks in advance!

 

[stwger]

I don't like pushing, but is there anyone out there who could help me?

 

[blueshark101]

I suspect you need helpers on the vlan interfaces...

interface Vlan-interface2
udp-helper server x.x.x.x

-Blue
The significant problems we face cannot be solved at the same level of thinking we were at when we created them

 

[stwger]

I have only one VLAN-Interface (homed in different subnets)

I tried the udp-helper settings with no success.

Udp-helper in my mind does the following:
- forward specified udp-packets (by port or sth. else) to one orde more destination servers
In my case this would be port 9 an hundreds of servers (clients receiving the wol packets)

-> please correct me if I'm wrong.

But I need generally forward L3-broadcasts (192.168.xx.255) to the subnets.

I'm absolutely clueless what step to do next and how to fix this issue.

Greetings!

 

[blueshark101]

Could do with seening your config file and a diagram if possible...

I would have expected you to have multiple VLAN interfaces rather than the one and clearly broadcast traffic does not, by default, get propagated across subnets.

-Blue
The significant problems we face cannot be solved at the same level of thinking we were at when we created them

 

[ShaneRamey]

I'm having the same problem stwger. I did some port mirroring and discovered that with ip forward-broadcast enabled, and monitoring the traffic coming into my uplink port, that the source and destination MAC address are both the address of the switch. I think 3com messed up here because this shouldn't be so difficult. I tried setting the udp-helper server as the IP broadcast address (.255 on a class-C) but these damn things don't work right. Interestingly the 5500G-EI seems to work correctly but the 5500-EI (no G) is cursed as far as I can tell.

 

[ShaneRamey]

My mistkae, you did say G in the title. In that case you should just need to enable ip forward-broadcast in system view and on each Vlan-interface. Contact me if you have anymore questions, I definitely got it working between two subnets. If anyone knows how to get the 5500-EI (no G) working please drop me a line.

 

[stwger]

Thank you for your replies!

@Blueshark: I'm unfortunately not able to send the configuration files because of company confidentiality reasons.

@ShaneRamey: I already enabled ip forward-broadcast in system view and also on the vlan-interface.

Is it possible that some broadcast suppression settings stop those packets or that subnet directed broadcasts are only delivered between different VLANs and not within one VLAN? -> So if, how to fix this?

Thanks.

 

[ShaneRamey]

I ended up using multicast instead of IP forwarding broadcasts, but I just wanted to share that with version 3.3.2 ep5 of the firmware I was never able to get ip forward broadcast to work on the 5500-EIs (which only have the "ip forward-broadcast" availabye in system-view). The 5500G-EI did work by using the ip forward-broadcast command in both VLAN interface view and system-view, but this didn't work for my application as I have many 5500-EIs deployed. I never did check with 3com support though, and I suppose they intend for it to work with their equipment because they made the command available for the 5500-EIs.

Shane