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I am investigating connectivity issues in a network setup with 4 routers - A1, B2, B3, and B4.

A1 is the modem/router that connects to the internet at large. It is using pretty much the default settings

WAN IP:       (assigned by ISP)
LAN IP:       192.168.1.1
DHCP range:   192.168.1.100-192.168.1.254
Subnet mask:  255.255.255.0

B2 is configured as a wireless access point. There is an ethernet cable connection between a LAN port on A1 and LAN port on B2. DHCP is disabled. It has a LAN IP of 192.168.1.2

B3 and B4 are both configured as routers within the network created by A1

WAN IP:       (assigned by A1 using DHCP)
LAN IP:       192.168.5.34
DHCP range:   192.168.5.100-199
Subnet mask:  255.255.255.0

This means B3 and B4 have distint WAN IPs - e.g. 192.168.1.100 and 192.168.1.101 - but have the same LAN IP and DHCP ranges.

In my research, I came across a post on Tom's Hardware that says B3 and B4 should not be using the same DHCP range, but it doesn't explain why

Just make sure each router uses different IP scopes. IOW, if we assume router #1 is using 192.168.1.x, then perhaps router #2 uses 192.168.2.x and router #3 uses 192.168.3.x.

Could these overlapping IP address ranges cause general connectivity problems for clients connected to these "nested routers" - i.e. B3 and B4? Or is the recommendation of using different IP scopes just a matter of good "hygiene"?

EDIT: Here is a diagram

Diagram of network with two subnets that have overlapping IP scopes

Enrico
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    This is high on my list of questions that would benefit from a diagram. Don't worry if you have to link it in from elsewhere (ie, you don't have enough rep to inline the image directly), someone will copy it in for you. – MadHatter Mar 19 '17 at 21:04
  • No worries, and thanks. Can you confirm that both B3 and B4 are NATting their 192.168.5 traffic before it goes out onto the 192.168.1 network, and that no host behind B3 will ever need to directly communicate with a host behind B4 (and vice-versa)? – MadHatter Mar 19 '17 at 21:35
  • I believe B3 and B4 are NATing their traffic - although I don't see an explicit option to enable/disable that. Hosts behind B3 do **not** need to communicate to hosts behind B4 and vice-versa – Enrico Mar 19 '17 at 21:38
  • If you ever need to grow your network then using the subsequent 3rd octet between routed networks could be a problem for expanding configuration where you could be using `192.168.1.0 /24` now and may need to scale one network up to `192.168.1.0 /23` for example so I personally like keeping those `10` apart such as `192.168.1.0 /24`, `192.168.10.0 /24`, `192.168.20.0 /24`, and so on to give each a little room for growth if it could be an issue potentially. – Pimp Juice IT Mar 20 '17 at 00:01

0 Answers0