delays printing over VPN, network problem?

[ChrisBeach]

Hello all,

I've recently setup a new plant the company I work for bought. Theres currently 2 DSL lines (internet) coming into the building, they appear to be 4mbit each. I setup 2 linux boxes to act as the edge devices and hooked a dsl line up to each. I setup pptp vpn on each device and hooked them both back into our network via vpn. I setup some routing to put all high priority traffic over one link (ERP System), and low priority over the other (everything else). Our ERP system is located on our main network, so anyone at this branch office connecting to it is going over the vpn links I setup.

Now my problem is, we have datamax label printers out on the plant floor, and our ERP system prints labels to them. Seemingly randomly throughout the day the labels stop printing, if you wait up to 15 minutes, they seem to print. If you restart the printer, they print. If you look on the windows server that our ERP system is running on, you see "Error Printing", I couldn't find anything in the event logs on this.

We have this exact same setup (minus the vpn) at our other locations and it works fine. It seems to me it would be something wrong with the label printer, but after 3 calls, datamax assures me it is not, so that just leaves me with the vpn.

I did make sure I could ping the label printer from the ERP server with a packet size of 1500, it did that without problem, I can't think of what else to try. Anyone have any ideas?

 

[jimbopalmer]

One comment, VPN operates at the speed of your Uploads, not Downloads, so 'they appear to be 4mbit each' is overstating your speed.

I tried to remain child-like, all I acheived was childish.

 

[technome]

Ping is basic.. Pathping the printer, see if you have packet losses along the way. Is flow control on or off on the printer port? Are you building up errors on the switch ports? The printer seems to be timing out, perhaps (guess), if you do not find any other faults, you might try a cheap print server device at the printer to buffer the prints before they hit the printer.


........................................
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[ChrisBeach]

I will give that a try (pathping) thanks technome.

Something I did notice is that the VPN link (that the print jobs are traveling over) is set to NOARP. I'm wondering if this whole problem could be due to the printer not sending/receiving arp packets to/from the server sending the print jobs.

Anyone have any thoughts?

 

[LawnBoy]

Well, you must have ARP in order to resolve an IP address. The fact that you can ping that printer tells me that you are passing ARP packets. Maybe not reliably...


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes

 

[ChrisBeach]

All the printers are setup to use our WINS server, so thats why I figured I was able to ping it, but maybe I'm wrong and maybe some ARP packets are making it over.

I tried turning on ARP Proxy in PPtP, but it gives an error, I'll investigate more when people are off the network tonight.

Thanks

 

[LawnBoy]

ARP is the protocol used by Ethernet to translate IP addresses (not names) into MAC addresses. Ethernet transmits data packets from one MAC address to another MAC address.

WINS is a name resolution protocol, similar to DNS.


"We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth." - Sherlock Holmes