same IP on 2 interfaces ?

RouterOS Beginner Basics
1

Hi.
I read “Top 10 RouterOS configuration mistakes” on url = https://www.youtube.com/watch?v=BkZHRD6svQU
Number 10 is “never set same IP on different interfaces”

But here comes my configuration :

   .-------------------.------.
   |       RB 750      |      | 
   |  10.139.130.33    | eth1 | --- PC proxy      ip = 10.139.130.34
   |  192.168.1.247    | eth2 | --- GW to ADSL    ip = 192.168.1.254
   |                   | eth3 | -
   |                   | eth4 | --- Nano5 Antena  ip = 10.139.130.35
   |                   | eth5 | 
   |                   |      | 
   .-------------------.------.

The RB750 is the router between a WLAN, whose data comes from the Nano5 antena,
a PC that has a Squid Proxy,
and the ADSL where the authorized users can access.

So, I have one IP for eth1 (10.139.130.33)
another IP for eth2 (192.168.1.247)
and here comes the problem :

*** the antena is in the same network as the PC ***

What IP shall I assign to eth4 ?

2

If you want to keep the Nano5 Antena and the PC proxy in the same subnet you can bridge the ether1 and ether4 interfaces and just set an IP address to the bridge, then you will have something like a two port switch:

/interface bridge
add name=br1
/interface bridge port
add bridge=br1 interface=ether1
add bridge=br1 interface=ether4

/ip address add address=10.139.130.33 interface=br1

I hope this helps.

3

This is *** EXACTLY *** the pointer to the idea I was missing

Thanks a lot, a lot, a lot