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Can't see OSX clients across subnets


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Hi all,

 

recently my company moved to a buiding where we have different subnets and VLAs.

Although I have followed the tutorial (http://kb.dantz.com/article.asp?article=1020&p=2) and manually added the subnets, I still can't see the OSX clients from Retrospect Server running on OSX 10.4.9. I can only see them all if I use their IP addresses but those are assigned by DHCP and going to change after some time the clients is not working.

I can only see the clients in my subnet (VLAN).

 

I have spoken with the network guy and according to him port 497 is open for TCP and UDP broadcasts and multicasts.

Is there a way I can check this is actually true? I mean, using some Terminal script or other utility which might tell me what's wrong with the network settings?

 

Many thanks for your kind attention

Ciao

Carlo

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It's a network thing. The whole purpose of a VLAN is to only show traffic for switch ports in that VLAN. Other traffic from other VLANs cannot and will not be seen. You have to add each switch port (not IP port) whose traffic you want other members of the VLAN to see to the VLAN.

 

Russ

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Thanks again, Russ.

I am trying to understand but since I now very little of networking, you should forgive my other questions...

According to your reply, each switch port hasto be added, but wouldn't this create a unique VLAN?

I am trying to figure out what specific request I have to submit to our network guy.

We have something like 8 VLANs across the floors and Retrospect clients (Macs) are pretty much anywhere.

Many thanks for your attention...

Carlo

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The whole point of a VLAN is that it creates a "virtual LAN" - the only traffic that appears on the VLAN is for switch port members that you have added to the VLAN. No traffic from other switch ports will appear on the VLAN. It's just as if the other switch ports weren't there. That's exactly what a VLAN is.

 

If you want clients on other VLANs to be seen by Retrospect, you will have to create a new VLAN with the Retrospect server in that VLAN and all clients that you wish Retrospect to see. This has nothing whatsoever to do with Retrospect or the IP (TCP/IP or UDP) ports that it uses.

 

There are also "tagged VLANs" that can be passed through Managed L2 and L3 switches that accomplish the same thing across a network fabric of multiple L2 and L3 switches that "port based" VLANs accomplish on a single switch. You haven't provided any information about your network infrastructure, so there's no way that we can suggest what is needed here.

 

Not to be abrupt, but a tutorial on VLANs and networks is outside the scope of a Retrospect user-to-user support forum because it has nothing whatsoever to do with Retrospect, and really doesn't belong here. I suggest that you look up VLAN in Wikipedia for some background information. The specifics of how to set up the VLAN for your specific needs depends entirely on your setup.

 

But realize that what you are trying to do, namely, have Retrospect see clients in VLANs other than its own, defeats the whole purpose of the VLAN structure that your network administrator has set up.

 

Russ

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Thanks again for the explanation. I'll submit it to our network guy too se if he can understand the requirements.

Our VLANs basically go according to the floors. We have two twin buildings with different VLANS and their own switches (a mean of 2-3 floors each), but you're right I can't give more info about it since I don't know the details of the configuration (brands, setup, and the like)

 

Still, I have to find the reason for the option to add subnets in Retrospect, that would make sense.

But you're right again, this is not the proper spot for a tutorial about networking.

Cheers,

Carlo

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The reason to add subnets in Retrospect is so that you can get the packets to the other subnets by normal IP routing. A broadcast packet is sent to the "all ones" broadcast address for a subnet (logical "or" of the network address with the one's complement of the subnet mask). VLAN technology is something entirely different than subnets. It's generally done for security purposes to isolate network segments (different from subnets) or to isolate broadcast traffic, even within a given IP space. It's at complete odds with what you are trying to do by getting Retrospect to see all clients across the different VLANs.

 

For some reason, your network administrator has set things up so that machines on one floor (VLAN) are blocked from seeing any traffic whatsoever from other floors (VLANs) and from passing any traffic between floors (VLANs). I don't know whether it's for security reasons or for some other reason. What you are trying to do runs completely counter to that architecture.

 

Russ

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