Configure cbs350 VLAN to assign a different IP range then the router

[kmercrer]

Hi 

I have a cisco cbs350 that is connected to a router that provided an IP range that I did not want.  The VLAN1 is directly connected to the router with DHCP. 10.1.10.x I changed this so the switch would provide the DHCP.

I created new VLANs 10, and 20 on the CBS350 and added IPv4 Interface static 192.168.10.200 and 192.168.20.200 and added the DHCP service on the switch. 

I assigned the trunk port for all the VLANs.

The Problem is the VLAN 10 or 20 is not assigning the 192.168 DHCP addresses and when I manually assign a computer's address to 192.168.1.x I no longer have access to the router. 

What step am I missing?

[Karsten Iwen]

You say that the switch should do the DHCP, but which device should do the routing between the VLANs?

• If it is the router, the router also needs a trunk-interface with your VLANs 10 and 20 and IPs in that subnet. The DHCP server should assign the default-gateway IP from the router.
• If it is the Switch, then you need a transfer-subnet between the switch and the router. This could be the 10.1.10.x subnet. If the switch gets its IP by DHCP from the router, it should be fine. But if you configure that VLAN on the switch with a static IP, you also need to point a default route to the routers IP.

[kmercrer]

Hi Karsten, Thank you for your reply. I don't think the router the ISP provides has a trunk. but LAN 1 that is the . I did also try making LAN10 the native LAN and all ports defined as access ports but I think my problem is not knowing how to point to the default route. I tried ACL but it did not work. I don't think I did it correctly if ACL is the way to do that. I just factory reset the switch to start over.  I was thinking of adding the 192.168 to VLAN 1 but still was not sure on when I change the DHCP to be on the switch if that would work. Or, If I keep VLAN 1 as 10.1.10. x not sure how to route the LAN 10 correctly to 10.1.10.1

Could you point me to a resource that explains this?

IPv4 Forwarding Table

Destination IP Prefix Prefix Length Route Type

0.0.0.0              0          Remote    10.1.10.1       VLAN 1

10.1.10.0         24          Local       10.1.10.64     VLAN 1

192.168.1.0     24         Local       192.168.1.200

[Karsten Iwen]

And There is the next Problem. The Router would need a route back to the switch for the internal VLANs. First check if the router is capable of extra static routes. Perhaps you need a different device there.

[kmercrer]

Thank Karsten, So could I turn on DHCP on the switch and add the static to VLAN 1 and not setup the other VLANs . In the end I'm just looking for the port to give out 192.168 and not 10.1. I will ask about the static routes. 

[Karsten Iwen]

Yes, the correct port config is part of the DHCP success. But if the rest of the infrastructure is not capable to deliver the needed services, you still can’t access the internet.

[kmercrer]

Hi Karsten, Currently our infrastructure is the ISP router and the new cisco switch. We currently have running the ISP router and a few netgear routers connected to the ISP router, On the NETGEAR router we could just define the internet IP address, the subnet, def gateway, and DNS 1 - 2, and enable DHCP, define the start address of 192.168.1 1 and the MAX # of users. With that I would get the IP address I wanted. I wanted to remove the extra netgear router and the hubs and use the 1 cisco switch. But having a problem doing this. I'm sure I'm just missing something in doing the configuration (the wizard did not help) to make the switch work and provide the IP address of 192.168.1.x. I'm wondering if this gives a better view of what I'm looking to do.

Thank you for replying to my post.

[balaji.bandi]

The Problem is the VLAN 10 or 20 is not assigning the 192.168 DHCP addresses and when I manually assign a computer's address to 192.168.1.x I no longer have access to the router

The port should belong respected VLAN. to get an IP address from DHCP.

192.168.1.x  ( are you sure this IP address correct, you have 10.X  and 20.X IP range?)

[kmercrer]

Hi BB, If I could have the switch assign 1 VLAN to 192.168.1.x address and route to the routers 10.1.10.1 I would be happy. I think I don't understand how the route process works. The things I did try did not work.

[balaji.bandi]

can you post show run - also have you enable ip routing for the switch to perform l3 functions.

[kmercrer]

Hi BB, When I set all the port to Level 3 the system hung and I needed to restart it. I attached the run file.

[balaji.bandi]

show run - not full config.

[jimstewart77]

The switch isn't going to assign any DHCP addresses becase there are no address pools assigned.  You have turned on the server but its not doing anything.  You should see entries for each pool looking something like this

ip dhcp pool network mainlan
address low 192.168.1.160 high 192.168.1.199 255.255.255.0
default-router 192.168.1.200
dns-server 10.1.10. I

should have a line identifying where the internet gateway is

ip default-gateway 10.1.10. I

Your VLAN20 also lacks a switch address.  The switch needs its own IP address on each vlan.

If the CBS350 can't see the internet (use ping to test and NTP services shoukld connect) then your not even close.

[kmercrer]

Hi, Yes the CLI I made an error with the more. I have a different copy here. Thanks for taking a look.

[jimstewart77]

L3 routing is enabled by default and is done on a global not port level.  It would have a "no ip routing" in your show run if it was disabled.