Connecting four different Networks

[Riemann5334]

I have four different industrial automation networks: N25, N10, N20, and N30. N25: x.25.0/24 (130 PLCs with Gateway x.25.230; 50 PLCs with Gateway x.25.1) All of them connected in the same Ethernet Switch and all of them permanently talking to each other. N10: x.10.0/24 (Gateway x.10.230) N20: x.20.0/24 (Gateway x.20.230) N30: x.30.0/24 (Gateway x.30.230) On Router A: N10 to VLAN port1 N20 to VLAN port2 N30 to VLAN port3 N25 to LAN port4 Nothing connected to the WAN port. I achieve communication between N10,N20,N30 and the ones of N25 that share the same Gateway, x.y.230 All the cases are static IPs, and there is no DHCP servers or other fancy thing. There is another existing network N21:x.21.0/24 with several routers and one of them have a network 192.168.20.0/24 somewhere in another location that has nothing to do with my N10. From a "higher authority" the two networks N21 and N25 are connected with a router x.25.1/192.168.21.5 This is the problem: From the Network N21, a workstation must be able to communicate with all the N10, N20, N30, and N25, but only the N25 that have a gateway as x.25.1 are the only ones accessible from the workstation (located in N21) I have three CISCO RSV4000 router. Question: How to connect them and their routing tables?

 

[bill001g]

You will need to put in static route in both routers telling them about the other.

You would point the 192.168.21.0/24 network to x.25.230 on the .1 router and point all the other networks to .25.1 on the .230 router. This fixes everthing except the .25 network. This is hard because it violates some of the design rules for subnets.
If you are lucky it will just work. Say 25.xx has a gateway of 25.1 but it wants to get to 20.aa. It will send its traffic to 25.1 and 25.1 will send it to 25.230 (because of your new static routes), which will then send the traffic to the correct end machine. The return traffic will go from the remote machine to 25.230 router and then directly back...ie not back though 25.1. You now have inconstant routing path...but it may or may not work.
The problem is that some routers are too smart. The 25.1 router may detect it is sending the traffic out the same port it received it on and block it or it may see that it never sees the return traffic and drops it. Most these are firewall type features that routers have on by default and you would have to find and disable if its possible.
The only way to really fix this is to add static routes to each end machine so it send the proper traffic to the proper gateway.

 

[enser]

My vote is always for a dynamic routing protocol like EIGRP or OSPF when trying to share RIBs between routers. Really all you need is one area (with OSPF for example), with each router participating in this area. It literally as easy as turning on OSPF, creating area 0, and then adding each of the 3 router's uplink interfaces to this area.
Not sure why you're using 2 GWs for clients in the same network (trying to load balance or something?)... but regardless as long as its as simple as you describe this will keep routing uniform and consistent in the environment.

 

[bill001g]

enser...problem is this is not "really" a cisco router it is linksys. On top of that it is more of a vpn/firewall than a router. At least this one supports static routes unlike many of the other products in the consumer market.

I suspect this is part of the reason cisco ditched the so called small business line of linksys routers. You cannot even compare them to the features of a IOS based cisco router.

 

[enser]

bill001g - you're absolutely correct. I should have looked up the device type! Just saw Cisco and stopped there. Of course I also shouldn't assume a re-branded Linksys can run a full suite of L3 routing protocols. You're also correct that at least you can manage it and it has basic L3 to begin with!

Haven't actually used a home/SMB switch for years... so its easy to forget.
To put things in perspective I recently 'scaled down' my home network to a Juniper SRX at the edge, a Juniper MX10 for my core BGP & MPLS 'needs' (aka playing around), a mix of Cisco 3750s & Juniper EX4200s for the LAN with a dash of Aruba WLCs for my WLAN. Excessive... definitely
Sounds like we're in similar professions so I'm guessing you understand the nice perk of toys you can acquire.
And yes, how nice was that Cisco/Linksys merger and its rather fast decoupling... Not too pretty and made me dissapointed in both parties. Oh well.


To get back on topic- think your answer gets the job done.