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Manufacuring Network

Q4U
Occasional Advisor

Manufacuring Network

I have a segment on the network that is handling the manufacturing floor. Another vendor handles that network, and it includes controllers for the manufacturing machines on the floor (not PC's). I don't know much about it, but it is connected to one port on our edge router, and the business network is on another port. One is 10.11.0.0/16 and the other is 10.127.0.0/16. At times the business network slows down for no apparent reason. When I capture packets on the Manufacturing network, I see that about 90% are dropped by the router. The dropped packets are of Ethertype 0x8874, and the length is 192 bytes.

This brings up 3 questions:
1. Is this normal for a manufacturing floor?
2. What is Ethertype 0x8874?
3. Could this be chewing up my router at times?

Thanks for any insight.
4 REPLIES
Alan_152
Honored Contributor

Re: Manufacuring Network

When you say "manufacturing floor", two ideas pop into my mind immediately:

1) Is the cabling to the nodes a shielded type or fiber?

2) Is any heavy-duty equipment connected on the same power circuit as your router?

As for 0x8874, looking it up with IEEE, it reads the following:

"8874 Broadcom Corp. Protocol unavailable."

Probably indicates you have broadcom NICs on your network -- very common and no big deal. However, it also leads me to suspect that you might have a speed/duplexing mismatch somewhere in the horizontal cabling plant.
Q4U
Occasional Advisor

Re: Manufacuring Network

As far as the shielding, another contractor is handling that network, so I am not sure.

There is no high voltage power anywhere near either (2810-G24) switch on that network, or my router.

Not too shocking that the interfaces on that network are Broadcom. They have been around for years.

I doubt I will get any help from the other contractor. He acts like his network is a black art or something. I may just have to install a router in front of his network, and VPN them together.

Thanks for your help.
Richard Brodie_1
Honored Contributor

Re: Manufacuring Network

Google suggests 0x8874 might be used for a loop protect function. If it's a low steady traffic like 1/second, that's probably normal. If it spikes, that's probably not so good.

It depends what it's 90% of: if the manufacturing network is fairly self contained, it's probably OK if most of the traffic that hits the router is hellos and junk like that.

Q4U
Occasional Advisor

Re: Manufacuring Network

It seems to be bursty. I'm trying to see if it corelates to the general slowdowns on the production network. Hard to say so far. Every time there is a slowdown I'm somewhere else.