Startup HomeLab

[Rekidu1337]

Hey all, I'm new to networking world, I have acquired a 3750x 48 port PoE from my organization (they retired it with new switches). I'm mainly interested in this switch as I read it's also a L3 Switch. One thing i'm struggling with configuring is my ISP modem to the switch, I currently don't have my own purchased modem, I have it leased by my ISP (no enough budget to get a modem currently). What I want to lab is creating my port #48 as the one that's coming from my ISP to the switch, and all my other ports get IP assigned by the 3750x making it the DHCP server and assigning IPs to my VLANs, I want to separate them by VLANs, ex. 10 (PoE cams), 20 (access desktops), 30 (smart devices). I know how to create the VLANs, assign the ports to each VLANs, I know that in order to create a port with routing capabilities I have to use ip routing and the no switchport command on that port. What i'm sort of struggling is on creating IPs from each subnet to the default router and then out to the ISP network to the internet. I'm probably very close to getting it right but if I had a separate router, I know feel more confident doing this trunking from SW to RTR and then just creating the sub IPs on that port. Kind of stuck when the switch itself is also working as a router. Any guidance works... Thank you!
P.S. sorry for the long post or if it doesn't make sense.

[Reza Sharifi]

Hi,

The issue is that you have to see how the ports on the ISP modem are configured. If the ports are configured as access ports, you can connect your 3750x switch to one of the ports and put all your devices in that same VLAN/subnet that is on the modem. If you are trying to have multiple vlans with multiple subnets on the 3750x, that is possible but the subnets will not reach the outside world (Internet) because the NATing is configured on the modem for the specific subnet you are using at home, and not for the other subnets you have on the switch. If you have access to the modem, you can find more info by logging into it and taking a look at the configuration. 

HTH

[Rekidu1337]

So the idea of creating Port 48 to grab whatever IP address the ISP provides me and then creating Port 47 as my L3SW/router to do PAT to Port 48 so it goes into the outside world wouldn't work? I was so hopeful. Ideally I'll just need to get rid of my ISP modem then, correct?

[Reza Sharifi · Accepted solution]

The 3750x series switches are not capable of doing NAT/PAT. Most ISPs setup and NAT one private subnet (usually in the range of 192.168.0.0) for you to use at home for your wired and wireless connections and if you want to add a second one, you would have to ask them or have access to the modem to modify the config. On the other hand, if you had a router, you could possibly connect the ISP connection to your router and do all the NATing yourself and build multiple private subnets on the switch and make them routable to the outside world. Usually, smaller ISPs are more flexible than larger ones like Verizon, Comcast, and AT&T, so you may want to talk to them.

HTH

[Rekidu1337]

Hey Reza,

Thank you for the response. I wasn't aware this switch didn't have the capacity to NAT/PAT which is a shame considering, like I mentioned I wanted to learn networking and was going to start with this SW. I still have other things I can do with it, but now I know my limitations. I really appreciate the time you took to respond.

[Reza Sharifi]

Good luck in your journey of learning networking!

The switch you have has a lot of features you can use and learn from. You can also purchase a couple of used routers on eBay and practice with them. They are not too expensive considering they are a few years old, but for what you trying to do they should be sufficient. Here is an example:

Please research and make sure the seller is reputable before purchasing.

https://www.ebay.com/itm/284074655493

HTH