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VLANS & UC520/CE520

Hi, I have a problem with routing across VLANs.

I have two data vlans set up on the above boxes: 192.168.6.0/24 & 192.168.3.0/24.

There is a UC520 box with its default ip in the 6.0 range, and all of the CE520s (three of them) also have an ip in the 6.0 range. All of the equipment are connected by the trunk ports.

The 6.0 network's default route is the UC520 and all clients can route correctly and more importantly see the CME/CUE web page at 10.1.10.1.

The 3.0 network's default route is an SBS server which is connected to one of the CE520 switches. All clients can route between each other and the SBS server no problem. However none of the clients including the SBS Server can see 10.1.10.1.

What I have done to fix this is set up one of the ports in the UC520 as being assigned to the 3.0 VLAN and connected one of the two switches with the 3.0 clients to that port. This hasn't worked.

I can't really experiment as it is a live network.

Any suggestions as to what is wrong?

Thanks

dphal

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Cisco Employee

Re: VLANS & UC520/CE520

Hi,

If I understand what your set up is, it sounds like you are routing 192.168.3.0/24 client traffic to the SBS server which does not have a route to the 10.1.10.0/24 network on the UC500. Typically, client traffic would be routed to the UC500 and coincidently is how the 192.168.6.0/24 is routing as you expected.

There are a couple of ways to solve this problem.

1) Add a VLAN3 interface on the UC500 with an IP address that is in the 192.168.3.0/24 subnet.

1a) Configure a DHCP server on the UC500 for this subnet and have clients get an address with a default gateway address of the UC500 IP address assigned to VLAN3.

1b) Add a default route in the SBS server to also point to the UC500 IP address assigned to VLAN3

This will allow full routing to all subnets the UC500 has in its routing table including the internet.

2) If you only want the 192.168.3.0/24 subnet to be able to reach the SBS server and the 10.1.10.1 subnet and prefer to use the SBS as your DHCP server and router for the 192.168.3.0/24 subnet, then you will need to add a static route in the SBS server to point to a UC500 interface.

So you'd repeat step 1) from above and then add the static route in the SBS server pointing at that newly configured UC500 IP address.

If you still have trouble getting to the 10.1.10.1 address, make sure you have a trunk set up between the UC500 and CE520 and VLAN3 is permitted through the trunk.

Hint: Using a tracert command on the Windows PCs can help you see each hop as it traverses the network to the destination. If it stops at the SBS server IP address then you know that's as far as the packet makes it and indicates that the SBS does not know how to route the packet forward. Typically the last IP address is the device that needs the routing table updated to pass the packet on to its destination.

Hope this helps,

Steve

4 REPLIES
Cisco Employee

Re: VLANS & UC520/CE520

Hi,

If I understand what your set up is, it sounds like you are routing 192.168.3.0/24 client traffic to the SBS server which does not have a route to the 10.1.10.0/24 network on the UC500. Typically, client traffic would be routed to the UC500 and coincidently is how the 192.168.6.0/24 is routing as you expected.

There are a couple of ways to solve this problem.

1) Add a VLAN3 interface on the UC500 with an IP address that is in the 192.168.3.0/24 subnet.

1a) Configure a DHCP server on the UC500 for this subnet and have clients get an address with a default gateway address of the UC500 IP address assigned to VLAN3.

1b) Add a default route in the SBS server to also point to the UC500 IP address assigned to VLAN3

This will allow full routing to all subnets the UC500 has in its routing table including the internet.

2) If you only want the 192.168.3.0/24 subnet to be able to reach the SBS server and the 10.1.10.1 subnet and prefer to use the SBS as your DHCP server and router for the 192.168.3.0/24 subnet, then you will need to add a static route in the SBS server to point to a UC500 interface.

So you'd repeat step 1) from above and then add the static route in the SBS server pointing at that newly configured UC500 IP address.

If you still have trouble getting to the 10.1.10.1 address, make sure you have a trunk set up between the UC500 and CE520 and VLAN3 is permitted through the trunk.

Hint: Using a tracert command on the Windows PCs can help you see each hop as it traverses the network to the destination. If it stops at the SBS server IP address then you know that's as far as the packet makes it and indicates that the SBS does not know how to route the packet forward. Typically the last IP address is the device that needs the routing table updated to pass the packet on to its destination.

Hope this helps,

Steve

New Member

Re: VLANS & UC520/CE520

Hi Steve,

Thanks for the reply.

To clarify one area yes you are right I do want the SBS Server on the 3.0 network to be the router for the 3.0 network.

I had set up an interface on the UC500 in the 3.0 range however I have been unable to ping this interface from any machine on the 3.0 network.

I need to test the traceroute as per your suggestion.

Am I correct in saying that since the CE520s are in transparent bridging mode then they should simply pass on packets from each network?

I have checked each of the trunks on the CE520s and the UC520 and they all appear to be configured correctly.

As an aside I changed the default route/gateway on one of the hosts on the 3.0 network to the UC500 box and tried to ping the 10.1.10.1 network and it still failed.

I can provide the config if that would assist.

Thanks again for your reply.

Cisco Employee

Re: VLANS & UC520/CE520

"I had set up an interface on the UC500 in the 3.0 range however I have been unable to ping this interface from any machine on the 3.0 network."

Here's some things to check.

1. make sure the subnet masks are the same on all the 3.0 machines including UC500

2. make sure the CE520 is configured with VLAN3 and the trunk port to the UC500 is configured to allow VLAN3

3. make sure that the speed and duplex settings of the ethernet port on the switch and the UC500 are the same.

You should be able to ping the 3.0 IP address on the UC500 from any 3.0 machine. Note: this doesn't mean you can ping the 10.1.10.1 address, your SBS will need a route to that subnet but first you need to get the connectivity to the 3.0 UC500 interface working.

"Am I correct in saying that since the CE520s are in transparent bridging mode then they should simply pass on packets from each network?"

Yes, each VLAN is a layer 2 broadcast domain and the CE520 bridges traffic between ports that are assigned to specific VLANs. That is, machine A can reach machine B on VLAN3 but machine A cannot reach machine C on VLAN5 without going through a router (e.g., UC500)

If you're still not having any luck.. Send me the config for both the UC500 and CE520 along with the output of the command "show cdp neighbor" from both boxes and I'll see if I spot any problems.

Sorry this is such a pain. It shouldn't be this difficult.

Steve

New Member

Re: VLANS & UC520/CE520

Hi Steve,

You're right when you say it shouldn't be this difficult.

I went back and tried a configuration that hadn't work previously and now it works so that devices on the 3.0 network can now ping and be pinged by devices on the 6.0 network.

The config I now have is to have an additional port on the UC520 in switching mode and one of the 3.0 switches attached to this port, as well as all of the ports except for the uplink ports on the CE520 switches belonging to VLAN3. The switched port on the UC520 and the uplink ports on the CE520 need to belong to the default vlan for some reason for this to work.

My only issue now is that I still can't ping the 10.1.10.1 device from the SBS box even after I set the route to the 10.1.10.1 device via the interface on the UC520. However if I add the route on a 3.0 desktop it works. I will keep investigating.

Thank you very much for your help.

Damian Halloran.

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