Manufacuring Network

[Q4U]

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.

[Alan_152]

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]

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]

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]

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.