Cisco 1751 router-on-a-stick 3

[tyl3r32]

Hi guys,

I'm pretty new to Cisco stuff and I'm trying to play around with some equipment. I've got a 1751 router and a 2950 switch and I am trying to setup a router on a stick to route between multiple vlans. Is this possible? I currently have the one and only ethernet port on the router setup with sub-interfaces. The problem that I am having is that I have a linux box on one vlan which is able to ping both sub-interfaces (in this case 192.168.168.251 & 192.168.1.1), but I have a Vista machine that is only able to ping the 192.168.168.251 interface. What am I doing wrong? Thanks in advance!

 

[tyl3r32]

Well guys, I finally got a chance to get back to this...however, the ip routing command did not work. I'm really not sure what is going on with this. I'm going to try starting from scratch when I get a chance, but if anyone has any suggestions, I'd be very appreciative. Thanks for all your help so far!

 

[routerlabs]

The configuration of the Cisco devices seems to be right. A 2950 switch is a switch, not a router. It can have one vlan interface for management, but it cannot take part in routing. It can switch more than one vlan, but it cannot route between vlans. Other devices like Catalyst 6500 can do both, but not the 2950 series.

The router should be able to ping your servers in both vlans. If not, check the IP numbers on the router and the servers.

Even if the router can ping both servers there is no routing connection between the serves. Each server needs a route that is pointing to the other server via the router. Server 1 says: To send a packet to Server 2 I have to give the packet to the router. The router knows how to reach the other server. This has to be configured in both directions.

List the routes on both serves:
On Linux: ip route show or netstat -rn
On Windows: route print or netstat -rn

Make sure you have the proper routing on the servers. A default route pointing to the router should do it.

I have an example online on

http://www.routerlabs.de/ethernet-switch/router-on-stick/index.html.

VLANS are created when you issue the "switchport access vlan 2" command. Show run shows the config, sh vlan just gives you some more information on vlans, and a different view.

Hope this helps.

 

[pmoorey]

1. Verify that all access/trunk interfaces are UP, verify all Sub-interfaces on router are UP.

2. Verify that all networks appear in the routing table as connected - 'sh ip route connected'

3. From each host ping their default-gateway

4. From each host ping the alternative sub-interface on the router, i.e. from PC in VLAN 2 try to ping VLAN 3 interface IP address.

5. Remember that firewalls on the hosts could easily be dropping your ICMP test.

Peter
CCNA, Cisco Qualified Specialist

 

[tyl3r32]

Thanks the responses guys. I've been really busy lately and I haven't had time yet to try that out. I'll let you know as soon as I do though. Thanks again!

 

[burtsbees]

Forgot to mention to make sure of your default gateways...for the Vista machine, 192.168.168.251; for the Linux box, 192.168.1.1. Also, in the switch, try this
no ip default-gateway

Burt

 

[tyl3r32]

OK. So I took a long time to get back to this, but I finally found the time : ) So, I started from scratch, erasing the configs on the router and switch, as well as the vlan.dat file on the switch. Created vlan 2 and 3 on the switch, configured the exact same way, except I set vlan 2 as native. Configured 2 sub interfaces on the router, the exact same way, except, once again, sub interface 2 is set for native. Put my Vista machine (IP 192.168.1.100, gateway 192.168.1.1) on vlan 2 and my Linux box (IP 192.168.168.101 gateway 192.168.168.251) on vlan 3. Here's the zinger...from my Linux box, I can ping everything; both sub interfaces on the router AND my Vista machine...however, the Vista machine will only ping itself and the 192.168.1.1 sub interface on the router. I tried turning off my firewall as well, and that didn't solve the problem either. It seems like this would be a Vista problem since I can ping everything from the Linux box and all interfaces are setup identical, but I just don't know. Does anyone have any insight on this matter?

 

[tyl3r32]

Woo hoo! I finally got it to work! I found out that I had to setup a route in Vista to get to the router through my second NIC. I did this by going into a command prompt and typing:

route -p add 192.168.168.0 mask 255.255.255.0 192.168.1.100

After I did that, everything works. Thank you everyone for your help. I wouldn't have been able to get this setup without you guys!