Having difficulties setting up CCNA home lab

I have a ATT 2Wire 3600HGV Residential Gateway to connect to the internet. I'm trying to setup a few routers/switches behind it just to mess around on. Here's what I'm trying to setup:

[ISP] -- [ATT 2Wire RG] 192.168.1.254 -- 192.168.1.110 [R1] 192.168.2.1 -- 192.168.2.2 [R2] 192.168.3.0

R1 is a Cisco 2610XM and R2 is a Cisco 2610. I have it setup so that I can ping from R1 out to the internet:

R1#ping 4.2.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.2.2.2, timeout is 2 seconds:
!!!!!

but if I ping from a source of s0/0 (192.168.2.1) I can't ping the RG (192.168.1.254). I'm assuming the reason why is because the RG doesn't know how to get to the 192.168.2.0 network. I tried figuring out how to set it up to route to that network, and the only option I could find in the setup is this:

Supplementary Network:
Add Additional Network
Router Address:
Subnet Mask:
Auto Firewall Open:

I tried adding the 192.168.2.0 network in there but it just says "Errors" and that's it. It doesn't give any details.
I also did a traceroute from the s0/0 (192.168.2.1) interface on R1 to the RG (192.168.1.254) and it doesn't look like the packet is even getting there:

Tracing the route to homeportal.gateway.2wire.net (192.168.1.254)
1 * * *
2 * * *
3 * * *

I understand that the RG doesn't have a route back to 192.168.2.0, but shouldn't the ICMP packet at least be making it to the RG and then be dropped?

Here's my routing table on R1:

Gateway of last resort is 192.168.1.254 to network 0.0.0.0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
C 192.168.2.0/24 is directly connected, Serial0/0
S* 0.0.0.0/0 [1/0] via 192.168.1.254
is directly connected, FastEthernet0/0

Any idea how I can get it setup so that packets can be routed from the 192.168.2.0 network to the 192.168.1.0 network and back? I don't have an access server (and only one PC with one serial port) and I'd like to connect to several routers/switches at once (via telnet) but I can't if they don't have connectivity.

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

Greenmet29

Are you able to ping 1.254 from a 2.* device?

migi

Greenmet29 wrote: »

Are you able to ping 1.254 from a 2.* device?

Nope, it fails. 2.1 can ping 2.2 and vice versa, but neither can ping 1.254

NetworkVeteran

migi wrote: »

I have a ATT 2Wire 3600HGV Residential Gateway to connect to the internet. Here's what I'm trying to setup:

[ISP] -- [ATT 2Wire RG] 192.168.1.254 -- 192.168.1.110 [R1] 192.168.2.1 -- 192.168.2.2 [R2] 192.168.3.0

RG doesn't know how to get to the 192.168.2.0 network. I tried figuring out how to set it up to route to that network.. I tried adding the 192.168.2.0 network in there but it just says "Errors" and that's it. It doesn't give any details.

I understand that the RG doesn't have a route back to 192.168.2.0

Any idea how I can get it setup so that packets can be routed from the 192.168.2.0 network to the 192.168.1.0 network and back?

So:
+ RG knows about 192.168.1.0/24
+ RG doesn't know abut 192.168.2.0/24
+ You don't know how to configure RG so it can learn about other networks.

How about an alternate suggestion, that doesn't involve fiddling with RG at all, but allows you to configure a private network with many subnets (16), routers & devices (14 per subnet).

[ISP] -- [ATT 2Wire RG] 192.168.1.254 -- 192.168.1.253 [R1] 192.168.1.241 -- 192.168.1.242 [R2] 192.168.1.225

1. Leave RG untouched (RG-to-R1 IP: 192.168.1.254/24)
2. Configure the R1-to-RG IP as: 192.168.1.253/28
3. Use /28 subnets within your home network. For example, between R1 and R2:
a. Configure the R1-to-R2 IP as: 192.168.1.241/28
b. Configure the R2-to-R1 IP as: 192.168.1.242/28
c. Configure the R2-to-R3 IP as: 192.168.1.225/228

You might wonder, what happens when RG tries to send a packet to 192.168.1.242, and ARPs for its address? R1 will actually use a feature called "proxy arp" and reply as if it were 192.168.1.242. Proxy ARP is enabled by default in Cisco IOS.

Greenmet29

Sounds like the first thing you need is a route from R2 to the 1.* subnet

Greenmet29

NetworkVeteran wrote: »

So:
+ RG knows about 192.168.1.0/24
+ RG doesn't know abut 192.168.2.0/24
+ You don't know how to configure RG so it can learn about other networks.

How about an alternate suggestion, that doesn't involve fiddling with RG at all, but allows you to configure a private network with many subnets (16), routers & devices (14 per subnet).

[ISP] -- [ATT 2Wire RG] 192.168.1.254 -- 192.168.1.253 [R1] 192.168.1.241 -- 192.168.1.242 [R2] 192.168.1.225

1. Leave RG untouched (RG-to-R1 IP: 192.168.1.254/24)
2. Configure the R1-to-RG IP as: 192.168.1.253/28
3. Use /28 subnets within your home network. For example, between R1 and R2:
a. Configure the R1-to-R2 IP as: 192.168.1.241/28
b. Configure the R2-to-R1 IP as: 192.168.1.242/28
c. Configure the R2-to-R3 IP as: 192.168.1.225/228

You might wonder, what happens when RG tries to send a packet to 192.168.1.242, and ARPs for its address? R1 will actually use a feature called "proxy arp" and reply as if it were 192.168.1.242. Proxy ARP is enabled by default in Cisco IOS.

Nice to know!

migi

NetworkVeteran wrote: »

So:
+ RG knows about 192.168.1.0/24
+ RG doesn't know abut 192.168.2.0/24
+ You don't know how to configure RG so it can learn about other networks.

How about an alternate suggestion, that doesn't involve fiddling with RG at all, but allows you to configure a private network with many subnets (16), routers & devices (14 per subnet).

[ISP] -- [ATT 2Wire RG] 192.168.1.254 -- 192.168.1.253 [R1] 192.168.1.241 -- 192.168.1.242 [R2] 192.168.1.225

1. Leave RG untouched (RG-to-R1 IP: 192.168.1.254/24)
2. Configure the R1-to-RG IP as: 192.168.1.253/28
3. Use /28 subnets within your home network. For example, between R1 and R2:
a. Configure the R1-to-R2 IP as: 192.168.1.241/28
b. Configure the R2-to-R1 IP as: 192.168.1.242/28
c. Configure the R2-to-R3 IP as: 192.168.1.225/228

You might wonder, what happens when RG tries to send a packet to 192.168.1.242, and ARPs for its address? R1 will actually use a feature called "proxy arp" and reply as if it were 192.168.1.242. Proxy ARP is enabled by default in Cisco IOS.

I can't even connect to R1 now, not sure what happened. Logging in from console, it keeps stalling at:
*Mar 1 00:02:10.962: %PKI-6-AUTOSAVE: Running configuration saved to NVRAM

I have to head to work so I'll have to try this tonight. But wouldn't the below two ip addresses conflict? If I have the .1.0 /24 network assigned on the RG, I didn't think it'd be possible to add an IP from that subnet with a different mask on the R1 interface? This is what you have:
192.168.1.254/24
192.168.1.253/28

I appreciate the help. Thanks!

migi

R1 is configured with a default gateway and it does have a route to the RG (192.168.1.254)

R2 also has a route to the 192.168.1.0 network - I have RIP running and it has the 192.168.1.0 network in its routing table. It's able to ping R1's interface -- 192.168.1.110 -- but not the RG (192.168.1.254)

I'm heading to work so I will post more info later. Thanks for the help, everyone.

Greenmet29

You may also check with some of the places that sell the RAM. If I remember right they were pretty knowledgeable about the subject.

woops .. wrong thread.

I know that some at&t routers won't let you do things. That being said, i've never had to setup anything like that and my routers have been on the net. Maybe someone else can chime in on what the problem might be.

NetworkVeteran

It will work. This scenario is actually not all that uncommon, when dealing with educational and corporate networks.

migi wrote: »

If I have the .1.0 /24 network assigned on the RG, I didn't think it'd be possible to add an IP from that subnet with a different mask on the R1 interface? This is what you have:
192.168.1.254/24
192.168.1.253/28

When you assign an IPv4 address and mask to an interface, IOS verifies that the given address is a valid host address for the given mask. It doesn't query neighboring devices to verify they have identical masks. That's now how IPv4 works.

But wouldn't the below two ip addresses conflict?

Nope. 192.168.1.253/254 are unique and valid host addresses for either mask, and they agree on the broadcast address.

The only tricky part is convincing RG to forward packets destined for 192.168.1.1-192.168.1.238 to R1. RG will believe they are directly connected, so when it wants to deliver a packet to them, it will ARP for their MAC address. R1, if configured with Proxy ARP (on by default), will reply with its own MAC address. RG then forwards the packets to R1 (who uses its routing table to properly deliver them to their final destinations). If proxy ARP were off, R1 would only respond to ARPs for its own IP address.