Solved: Configuring 851W Router as Second Router to Home Network

natestreet · ‎02-24-2008

This should be a pretty straight forward question but I am having trouble with configuring the router as I have no prior knowledge with Cisco IOS.

I purchased the 851W to practice for the CCNA which I eventually plan to prepare for but am currently pursuing other certs at the moment. With that said, I have a "Production" network which the house uses and a Lab network which is where my Cisco router fits in the equation. For what it's worth, I can not (do not) want to change anything with the way things are currently set up. They are using a LinkSys (WRT54G).

I've included a JPEG of what a workable solution is however, I do not know how to configure the Cisco IOS with these settings. Any help would be greatly appreciated.

Pretty much, the Lab network would run on a different subnet as the rest of the home network. Questions I have are would the Cisco router use my Linksys Router as the Default Gateway or the ISP's Internet Default Gateway.

Any help would be greatly appreciated, I have access to all administrative tools for both devices, it's figuring out what to put in them that is the hard part!

Nate

JORGE RODRIGUEZ · ‎02-24-2008

Nate, you are very welcome..I am also very glad I was a help and that you are preparing for your CCNA which Im sure you will do very well, study alot as well as do practice labs, I would also recommend to participate in these forums either by reading threads helping others or asking questions as this is the only way to achive full understanding of

networking/telecommunications .

"Do you know if the 851w is halting Discover Broadcast on that subnet?"

If you have a Windows DHCP server and want to use it to handle IP addresses to various subnets within your LAB environment you would need to configure IP helper-address under each of the interfaces of each of the subnets thus dhcp/BootP arp broadcast are fordwarded to dhcp server IP.. and yes! you router IOS is 1542 complient.

e.g

interface fastethernet0/1

Description 192.168.2.0_subnet

ip address 192.168.2.1 255.255.255.0

ip helper-address 192.168.2.201

See Ip helper-address http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/cs/csprtn1/csipadr.htm#2736

Best Rgds

Jorge

Don't forget to rate any helpful posts as resolved if it did helped

Jorge Rodriguez

View solution in original post

JORGE RODRIGUEZ · ‎02-24-2008

The answer is yes, for your 851W in 2.x subnet you can simply configure a default route which will point to your LinkSys router LAN Ip interface.

851W:

ip route 0.0.0.0 0.0.0.0 LINKSYS_LAN_IP_192.168.1.1

on LinkSys:

I believe your model should give you capability of configuring static routes so you need to tell linksys how to get to 192.168.2.x network.

e.g

Destination IP address of Subnet: 192.168.2.0

Subnet Mask: 255.255.255.0

Gateway IP: 851W_LAN_IP e.g 192.168.1.2

The static route on linksys is only needed if you want 192.168.1.x network be able to talk to 192.168.2.x network.

Thats it

If you have trouble lets us know.

Rgds

Jorge

Jorge Rodriguez

natestreet · ‎02-24-2008

Jorge! Thank you that worked perfectly!

This was good practice as I am preparing for the 70-291 exam! I think I'll say no to software routers for the time being!

I did have to do some modifications to the 851W in addition to your initial suggestion. Here is what worked for me:

1. Added a static default route to 192.168.1.1

2. Configured FastEthernet4 to use 192.168.1.2 Static IP

3. Configured FastEthernet1 to use VLAN1

4. Configured VLAN1 as 192.168.2.1 network

From there, configuring the static route on the LinkSys to talk to the Cisco router was a snap. Even though that I did not "need" this functionality for my lab, it did help me troubleshoot the Cisco router.

The next "task" for me is to migrate my current lab over to the 192.168.2.x subnet.

I had the idea of configuring a superscope on my DHCP server to distribute IP addresses to the 192.168.2.x subnet until I got my lab network fully up and running on the 192.168.2.x subnet. Do you know if the 851w is halting Discover Broadcast on that subnet? I imagine it would but do you know of a way around this? I turned off the DHCP server on the router itself and am currently using a static IP to talk on the two subnets. I suppose the technical term is if the Cisco 851W is 1542-compliant? I haven't seen it mentioned in any of the documentation.

Thanks again Jorge! That was a huge step in the right direction!

JORGE RODRIGUEZ · ‎02-24-2008

Nate, you are very welcome..I am also very glad I was a help and that you are preparing for your CCNA which Im sure you will do very well, study alot as well as do practice labs, I would also recommend to participate in these forums either by reading threads helping others or asking questions as this is the only way to achive full understanding of

networking/telecommunications .

"Do you know if the 851w is halting Discover Broadcast on that subnet?"

If you have a Windows DHCP server and want to use it to handle IP addresses to various subnets within your LAB environment you would need to configure IP helper-address under each of the interfaces of each of the subnets thus dhcp/BootP arp broadcast are fordwarded to dhcp server IP.. and yes! you router IOS is 1542 complient.

e.g

interface fastethernet0/1

Description 192.168.2.0_subnet

ip address 192.168.2.1 255.255.255.0

ip helper-address 192.168.2.201

See Ip helper-address http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/cs/csprtn1/csipadr.htm#2736

Best Rgds

Jorge

Don't forget to rate any helpful posts as resolved if it did helped

Jorge Rodriguez

natestreet · ‎02-25-2008

That is really good to know about the IP helper-address. I will need to try that the next time I play wih the router.

I had another question though which I should have brought up originally. Even though the router is working correctly with the VLAN oon a seperate subnet, shouldn't I be able to configure one of the fastethernet ports to the 192.168.2.0 subnet and not even worry about VLANs?

The CCNA will be a ways for me but I do plan on learning the Cisco IOS! As a programmer, this looks like it will be right up my alley!

Nate

JORGE RODRIGUEZ · ‎02-25-2008

Nate, you may live with just one subnet and one vlan in your LAB which I believe the default vlan for the 851W router is VLAN1, but it all depends what your requirements are and type of switch you have for LAB LAN if you wanted to create additional Networks and VLANS in 851 router. I am not sure but I believe 851W does not support VLANS meaning you cannot create SVI interfaces if you were to create additional networks in your LAB, you would need a L3 switch to create additional networks/VLANS in your LAB.

Best Rgds

Jorge

Jorge Rodriguez

natestreet · ‎02-27-2008

Thanks alot for the help Jorge. I have not had time to play around any more with my home lab network. For now, the VLANs will work just fine. I was concerned primarily about having enough ports to connect my three computers to (2 DCs, 1 XP). But if I can just have a switch on the VLAN port than that will work just fine for my home lab for now.

We use VLANs at work, however we only have the IP Phone System run on the VLANs.

Anyways, the CCNA is a future goal after the MCSEs!

Thanks again for the help!

Nate

JORGE RODRIGUEZ · ‎02-27-2008

Nate, you are very welcome and Im glad you resolved the issues. Thank you for the rating, if you have questions in the future I recommned when you have time to participate in these forums, there is a sea of information provided by forum participants.

Best Rgds, good luck in your studies

Jorge

Jorge Rodriguez