Managed Switch's

[The Plc Kid]

Rob

All these features can be used together.

From your previous posts in this thread you want to have 1 network so you will not need to use vlans and with the equipment you listed you should not need to change port configurations.

All you should need is IGMP snooping and Querier and you may want to employ QOS to give controller to drive priority over controller to HMI maybe but with the amount of devices you have I doubt even that will be necessary.

 

[The Plc Kid]

Also I think out of the box the IGMP snooping and Querier is turned on on the 6000 and 8000 switches. If you employ more than 1 switch then the unit with the lowest assigned IP address will become the querier and you don't have to change anything.

 

[robw53]

So I wouldn't need to use port segmenting/VLAN's to isolate drives/HMI's from the Mixer PLC's to reduce I/O traffic would the IGMP Snooping cover this?

 

[The Plc Kid]

Some people like to put their HMI traffic and IO traffic on seperate networks but that is mostly done when you have larger node counts than what you have. You can do it either way with the amout of devices you have.

IMO with the config you have laid out and the amount of devices you have I don't feel as it would matter which way you do it. I feel it is just preference with the amount of hardware you have. On larger machines/networks it is necessary to segregate things though.

 

[robw53]

Ok I will go with your advice and use IGMP instead of VLAN'S .

Cheers

 

[The Plc Kid]

For your current application ok. But for your overall knowledge you stall want to use IGMP when using multicast even within a VLAN.

Remember a layer 2 VLAN is nothing more than making 2 or networks within a single switch or multiple switchs.

In a example 8 port stratix 6000 I can have a network of 192.168.1.xxx and it is assigned to ports 1-4 and a separate network of 10.10.60.xxx and it assigned to ports 4-8

I can put my I/O and drives on 10.10.60.xxx and I want IGMP turned on and on the network of 192.168.1.xxx I can put my HMI's and some non critical I/O and still turn on IGMP because of the multicast traffic.

Because it is a stratix 6000 these vlans can't see each other and each network will only communicate to my logix processor via its own network interface which would be a ENBT. You could not comm to both these networks with a compactlogix with a built in port though.

Using a stratix 8300 or any router or layer 3 smart switch I could have communications between 10.10.60.xxx and 192.168.1.xxx.

IGMP snooping works in VLANs on the stratix 6000 the only thing different is the querier is shared between vlan's. There is no Querier per vlan in the 6000.

 

[robw53]

Thank you for the explanation, a couple of things though, having separate VLAN's with a layer 2 switch how exactly can the compact communicate to the other network if the switch doesn't allow communication over the different networks?

Also having a separate querier for each VLAN as opposed to a shared one what advantage do you get with that?

Are you limited to the number of VLAN's you can have with either a layer 2 or 3 switch, or is this dependant on the switch itself?

Rob

 

[The Plc Kid]

In most cases if you wanted to split up your network into 2 logical networks like drives and I/O on one and HMI's and data collection / historian on another you would need a controler that supports multiple nic's or in AB speak ENBT modules.

The model of compact you have only has a built in nic and you can't add the enbt modules to it. The 1768-L4X series of compact controlers can have 2 enbt modules.

Using a computer you could talk to 2 different networks with 1 port that is called binding but in AB hardware you can't do that.

As far as a seperate querier that is only used in large switches with many different networks for routing efficiency.

In some switches the vlan max is a hard number and in some switches it is based on the amount of nodes on the network. In most cases if you have that many nodes you will swamp the switch with trafic and chew up all its throughput before you max out your vlans.

 

[flowdam]

Kid- Thanks for the explanations on which switch to use for the different applications. I would like to ask another question if you don't mind. My particular scenario plays out like you describe for the layer 3 switch, but I don't know that I'm ready to drop 3g's for the it. All I'm wanting to do is basically bridge between my plant network(10.71.XXX.XXX) and a control system that I can use the standard 192.168.1.XXX you speak of. This way bubba can change out a remote I/O module without knowing BootP, but I can assign one plant network address that all the communication and programming can pass through. Would there be a more cost effective solution to doing this routing? Maybe a Stratix 6000 with some other basic router or possibly the L208-F2G-S2 Lynx layer 3 managed switched referenced earlier at $2000 is as inexpensive as I'm going to get.

All comments or alternative solutions welcome.

For your current application ok. But for your overall knowledge you stall want to use IGMP when using multicast even within a VLAN.

Remember a layer 2 VLAN is nothing more than making 2 or networks within a single switch or multiple switchs.

In a example 8 port stratix 6000 I can have a network of 192.168.1.xxx and it is assigned to ports 1-4 and a separate network of 10.10.60.xxx and it assigned to ports 4-8

I can put my I/O and drives on 10.10.60.xxx and I want IGMP turned on and on the network of 192.168.1.xxx I can put my HMI's and some non critical I/O and still turn on IGMP because of the multicast traffic.

Because it is a stratix 6000 these vlans can't see each other and each network will only communicate to my logix processor via its own network interface which would be a ENBT. You could not comm to both these networks with a compactlogix with a built in port though.

Using a stratix 8300 or any router or layer 3 smart switch I could have communications between 10.10.60.xxx and 192.168.1.xxx.

IGMP snooping works in VLANs on the stratix 6000 the only thing different is the querier is shared between vlan's. There is no Querier per vlan in the 6000.

 

[nwboson]

IGMP snooping - great idea, but there are cheaper more reliable alternatives

Reliable setup of networks for industrial control is a tough topic to learn. I've setup multiple networks that span the globe using VLANs, routers, VPNs, and managed switches within the networks. I found it troubling how industrial networking equipment suppliers have spread the notion that IGMP snooping is important. I don't buy it for one simple reason: industrial networks should never be configured dynamically. They should be statically configured to handle the worst case traffic scenario so you KNOW your vital plant data comm is 100% reliable.

IGMP snooping helps the switch minimize problems from ill-mannered devices that perform broadcasting (such as Allen Bradley Compact Logix and Control Logix): snooping helps limit the broadcasting domain. But your network segmenting should have done that in the first place.

My recommendation would be to simply use a quality managed switch if you want to connect to multiple subnets at once, or use carefully layed out unmanaged switches that are only connected to particular subnets. Then connect the subnets to a router and use the router as your forwarding/comm manager. The broadcast domains are fully managed this way just like the IGMP snooping - each subnet is a broadcast domain. This concept of switches that connect to routers that manage domains is how the entire Internet is designed and works so well: we PLC engineers simply need to follow the same paradigm.

There are lots of good industrial switches out there: pick your favorite brand and flavor of mounting / power supply scheme. Industrial routers are much tougher to select and configure.

I tend to now buy the Cisco Linksys managed switches (SGE2000) for larger installations (VERY cost effective, super reliable) and mount them in their own cooled rack. I use the Mikrotik RB450G router as my preferred router for panel mounting. The 450g can do about any router trick imaginable and mounts nicely in its aluminum case to a panel. This setup allows fully redundant wiring between switches (great idea in industrial networks) using link aggregation and LACP. It supports VLANs so you can appropriately segment your networks (I suggest ONLY using port VLANs and no tagged VLANs).

One thing I noticed in the prior drawing was a ring. If a ring is present, make real sure your network supports RSTP to break the ring or broadcast storms WILL OCCUR. The Cisco/Mikrotik setup above is capable of supporting RSTP.

 

[robw53]

when i put the ethernet cables between the 3 panels i went about it the wrong way without look into it properly and didnt realise until after that i couldnt configure it like that, so i no longer have the link between the two mixers, and now i have my Stratix 6000 fitted and working.
still alittle more fine tuning and utilising the predefined tags.

Rob

 

[The Plc Kid]

The primary reason for people pushing manged switchs with IGMP snooping was before logix V18 all you had was multicast and unicast was not even a option when V18 cam out it was a option and I think in V19 and above it is the default so if you are running V18 firmware you will need to do some legwork and see how your system is etup and if you are using v19 or above a unmanaged switch without IGMP will be fine for most small to mid sized networks.

I myself still like having a managed switch for the diagnostic and triubleshooting features.

 

[flowdam]

Thanks for the feedback everyone.

I'm going to look farther into the unicast option. Is this also something that can be configured in the latest revision of PanelviewPlus HMI's? They seem to be one of our biggest culprits for sending unwanted traffic to the network.

 

[robw53]

We have a network with 6 L32E with 5 PV 600's and 1 PV+1000 one of the PLC's is producing and consuming between the other 5 processors with no managed switch, this was setup with the 5 processors running V16 and the main one running either V18 or 19 if I updated the firmware on the 5 processors to V19 would I need to reconfigure anything or would they default to Unicast messaging even though at the moment they are multicast?

Rob