Home Networking

198 readers

1 users here now

A community to help people learn, install, set up or troubleshoot their home network equipment and solutions.

Rules

Please stay on topic.
Please use the search function to look for keywords related to what you want to ask before posting since most common issues have been answered.
No Ads. This community is for support and discussion. Ads and self promotion are not welcome here.
No product reviews or announcements. If you have a question about a product, be specific about what you want to know.
Be civil. Don't be a jerk. Not being a jerk is surprisingly easy.
No URL shorteners. URL shorteners tend to hide the real use of a link. For this reason, please use normal links, even if they're long.
No affiliate links.
No gatekeeping. With profession shall come professionalism. Extend help without judging others for their ignorance. The same goes for downvoting of comments or posts for "stupid questions" or not being as knowledgeable as others.

founded 1 year ago

MODERATORS

[email protected]

What would happen if 2 routers on the same ISP or same ISP WAN IP subnet had the same MAC? (alien.top)

submitted 11 months ago by [email protected] to c/[email protected]

5 comments fedilink hide all child comments

Just a random question/thought that popped up in my head: If you had one router with its real mac address connected to the internet on a particular ISP, and you cloned the Mac of another router to make it the same of the 1st one and connected it to the same ISP, would it make the connections for both or just one connection unstable, not work at all or would the ISP-level routing work around it?

As far as I'm aware ISPs (at least Virgin) lease routers their IP address based on their MAC. Essentially the ISP will be trying to lease the same IP to 2 devices at once.

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 1 points 11 months ago

Once I had 2 firewalls configured in High Availability for redundancy, active/passive, so if one dies the other becomes active. They both plug into the same ISP and use MAC address cloning to achieve this. Well the link between the 2 firewalls for heartbeat went bad and both became active with the same MAC.

The effect I experienced was 50% packet drop, every other ping failed as they both fought each other. Lesson learned and now I use at least 2 links between both firewalls in case one fails.