FOG Multicast on different VLANs
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Hi,
We have currently a FOG server running on VLAN 1, that unicast round about 40 pcs in VLAN 2 - 5 (not the best approach). To optimize that, I wanted to try to run multicast, but sadly our switches are just Layer 2 switches and they don’t support that on other VLAN (as far as I read, not a big network guy myself).
So my idea was now: The FOG server is running on a VM, is it possible to give that machine just 4 more virtual network adapter (for each VLAN one) and reconfigure the IP address on the clients to one thats on there VLAN? Somehow I think that would be too easy.
Or do I need to have a second FOG Server in that specific VLAN that just using the main FOG storage?
What else could I do to optimize the workflow?
Thanks in advance!
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@sega said in FOG Multicast on different VLANs:
I wanted to try to run multicast, but sadly our switches are just Layer 2 switches and they don’t support that on other VLAN (as far as I read, not a big network guy myself).
Layer 2 switches are good enough. Hopefully they are managed switches, that will make them work a bit better. Turn on igmp snooping on the switches. What that will do for you is enable sparse mode (i.e. only ports part of the multicast will transmit multicast data) without it the switch will work in dense mode where multicast traffic will be sent to all ports (impacting the bandwidth of devices not part of the multicast).
Muticasts are typically restricted to the current vlan. Where the magic happens is on your router between the vlans. Your router needs to be configured to forward muticast traffic between the vlans. This is typically done with a igmp helper / proxy / relay service much like dhcp needs a helper service to forward dhcp traffic from remote vlans to the vlan that has the dhcp server. This service running on your router will send the multcast data between the subnets.
So my idea was now: The FOG server is running on a VM, is it possible to give that machine just 4 more virtual network adapter (for each VLAN one) and reconfigure the IP address on the clients to one thats on there VLAN? Somehow I think that would be too easy.
This won’t work because when FOG service was designed it was designed to only support a single imaging network. Your fog server can have 4 network adapters, but only one can be the imaging network adapter. The rest will only work as management interfaces.
Or do I need to have a second FOG Server in that specific VLAN that just using the main FOG storage?
If you have no other option you can use a fog storage server here on the remote vlan. The issue is that only the FOG server supports muticasts. The fog storage nodes only supports unicast imaging.
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@george1421 said in FOG Multicast on different VLANs:
Where the magic happens is on your router between the vlans. Your router needs to be configured to forward muticast traffic between the vlans.
As far as I know that’s the problem. The router between is a Sophos which can’t forward that traffic (Asked a 2nd person about that).
To the multiple adapter topic: I looked up some threads yesterday where people tried it (for example: https://forums.fogproject.org/topic/12907/multi-network-multi-nic-fog-server-config-help/3)
So some people already tried it?
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@sega said in FOG Multicast on different VLANs:
So some people already tried it?
Yes and so have I. You would need some way to dynamically change the network adapter defined in the global FOG settings to change the network adapter. You might also need to change a file called
/tftpboot/default.ipxeto point to different interfaces. You might be able to get around this by setting up multiple tftp servers on the fog server, where each tftp server bound to a different interface and had a different home directory, that would be more of a long term change. And then you need to work out a way to update the imaging network interface in the fog settings depending on what interface you wanted to image using. There may be more crafty ways about doing this, but this is just off the top of my head. -
@george1421 said in FOG Multicast on different VLANs:
@sega said in FOG Multicast on different VLANs:
So some people already tried it?
Yes and so have I. You would need some way to dynamically change the network adapter defined in the global FOG settings to change the network adapter. You might also need to change a file called
/tftpboot/default.ipxeto point to different interfaces. You might be able to get around this by setting up multiple tftp servers on the fog server, where each tftp server bound to a different interface and had a different home directory, that would be more of a long term change. And then you need to work out a way to update the imaging network interface in the fog settings depending on what interface you wanted to image using. There may be more crafty ways about doing this, but this is just off the top of my head.So vacation is done, back to this problem.
I see, there are some more difficulties on the way.
In the meantime my colleague looked into the router and found a PIM function (Protocol Independent Multicast) and activated that.
I started a test run and the PCs are going in the Partclone process (Starting to restore image). But they are stuck in that screen, like they waiting for something or can’t get the data?Is there something that I can look up, to see where the problem is?
Thanks in advance.
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@sega said in FOG Multicast on different VLANs:
Is there something that I can look up, to see where the problem is?
Well your router supporting PIM is a good sign. Some routers have a service called igmp proxy or igmp relay, or even igmp snooping (you will find this more on switches, but check). This service typically has a number of interfaces to listen on and then a master interface where your multicast source lives. Its job is to relay the multicast requests to the proper interface.
PIM has two modes sparse and dense, that may be just for switches, I don’t remember. Sparse mode only sends the multicast traffic to the subscriber’s port, where dense just blasts out the muticast to all ports. You want sparse mode if possible, that way only the ports with a multcast receiver will see the traffic and not flood your network.
