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Configure same subnet on 2 ports on 5660 from CL?

Can I use the same subnet on 2 ports ?   Century Link (my fiber ISP) said they can't configure the 5660 to do this........ ?????   !!!!

I have a Century Link provided 5660 for my internet connection with a supplied /29,   port 2 is configured for internet,   port 3 is unused, port 4 is for my voice service, and 5 is my uplink from Fiber.

I want to activate/have configured port 3 to use as another port for internet access that I can use in seperate Ubiquity Security Gateway , Port 2 currently is in another gateway/router for my lan. (I am upgrading hardware and want to have the new gear up and tested before making the switch. SO i want both systems running at the same time (2 different physical networks).

I have 5 public IPs to use so can use a different IP for teh USG. CL said i would have to either purchase another /29 or split mine into /30s.    This doesn't seem correct to me.  Why can't they configure 2 ports for my internet access.   (I know i can just add another switch inline before my current gw/router, but i don't want to add a point of failure if i don't have to.)




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Re: Configure same subnet on 2 ports on 5660 from CL?

Can I use the same subnet on 2 ports? 

This isn't something that is configurable - you will run into issues with ARP and other protocols that operate based on layer 3 broadcasts that both interfaces would be expected to process/reply to. 

If the ISP is willing to break out the subnet into 2 seperate /30's then you can use 1 on the WAN connection like currently configured, then utilize the alternate address space for the secondary connection at the cost of 2 assignable IP's most likely. 

The other option is to add the IP's as a secondary address to your current interface and port forward that traffic downstream like you've already outlined. 

ADTRAN Product Support Engineer