LAN Routing

Re: Best way to connect 2 LANs (internal networks)?

 
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stlm
Occasional Advisor

Best way to connect 2 LANs (internal networks)?

Hello,

TL;DR: which is best? have an IP from LAN 1 in the router in LAN 2 and route it via this route, or have a new specific subnet between the 2 routers of the 2 LANs?

I have connected two (internal and trusted) LANs in two different ways, and both seem to work fine, so now I wonder which one is the "better" way...

Option 1

Have the router in LAN 2 configured with an IP from LAN 1.
So for a host in LAN 1 to reach a host in LAN 2, the router in LAN 1 will forward packets to the LAN 1 IP address in the LAN 2 router. Later the routes will be learned so the host will forward the packets directly to the LAN 1 IP in the LAN 2 router.

LAN 1: 10.0.0.0/24
Router GW IP: 10.0.0.1
host: 10.0.0.50

LAN 2: 10.1.1.0/24
Router GW IP: 10.1.1.1
Router IP from LAN 1: 10.0.0.200
host: 10.1.1.50

A traceroute from a host in LAN 1 to a host in LAN 2 will look like:

10.0.0.50 - 10.0.0.1 - 10.0.0.200 - 10.1.1.50
and once the routes have been learned, subsequent packets could be forwarded as:
10.0.0.50 - 10.0.0.200 - 10.1.1.50

Option 2

Have a new subnet (consisting of just 2 IPs) between the routers in LAN 1 and LAN 2.

LAN 1: 10.0.0.0/24
Router GW IP: 10.0.0.1
Router GW to LAN 2: 10.10.10.1
host: 10.0.0.50

LAN 2: 10.1.1.0/24
Router GW IP: 10.1.1.1
Router GW to LAN 1: 10.10.10.2
host: 10.1.1.50

So a traceroute from a host in LAN 1 to a host in LAN 2 will look like:

10.0.0.50 - 10.0.0.1 - 10.10.10.2 - 10.1.1.50

Thanks in advance!,

2 REPLIES 2
-Alex-
HPE Pro
Solution

Re: Best way to connect 2 LANs (internal networks)?

Hello  stlm,

I would do it like the following:

host->router1<---->router2---->host2

LAN 1: 10.0.0.0/24
Router GW IP: 10.0.0.1
host: 10.0.0.50

LAN 2: 10.1.1.0/24
Router GW IP: 10.1.1.1
Router IP from LAN 1: 10.0.0.200
host: 10.1.1.50

connection between the routers in L3(ip address on interfaces between the routers) router 1 ip  10.10.10.1/30, router 2 ip 10.10.10.2/30

route on router 1 - to reach 10.1.1.0/24 next hop 10.10.10.2/30

route on router 2 - to reach 10.0.0.0/24 next hop 10.10.10.1/30 

Hope this helps!

I am an HPE Employee

Accept or Kudo

stlm
Occasional Advisor

Re: Best way to connect 2 LANs (internal networks)?

Thank you Alex, 

that's, in fact, the option I currently have, each router with its own IP for their LANs and a new exclusive subnet for the link between the routers. Except I use a /31