Cisco Router 2821: Will this work?

[Aerone803]

I hope this is in the right forum... Alright everyone, I have a bit of an issue here... 

I am attempting to put a Cisco 2821 router onto my home network, yes home lol. I'm trying to do this for a learning process as well as use this enterprise level router to help control my internal network. My goal is to have the Cisco router connect right to the modem and then have two wifi routers connect to the Cisco router, and I plan to have them be on separate networks. I want to apply a rate limit command on one link and designate that link as the guest network(I've tried using an end user router with guest network ssid capabilities but it failed, hard). I also want the Cisco router to have dhcp off while the wifi routers keep them on but I understand that might not be best as the Cisco router may need to assign the routers an ip address for them to work. 

However the problems I see are... The router only comes with two gigabit ports and I need three ports, not necessarily being gigabit, so problem A would be getting another module that can support simple data transport for the home router. I do think I have a module that can work, the NME-16ES-1G, however I'm not sure if I can use the ports as simple ethernet ports. I mean I know I have a good chance at making it act like an L3 port but will this be enough? Any tips anyone?

[Jay Lohano]

Hi Aerone803,

If you can make the module work with Cisco 2821 then you can make this solution work. 

I am assuming you have an internet connection. Plug that on Gig0/0 with all the relevant IP Address and a defualt route. Then, connect the second port i.e. Gig0/1 to the NME-16ES-1G module. This will be your trunk port. Now you can create to VLANs on your switch module, create subinterfaces on Gig0/1. Plug both your wireless routers to the switch module. Configure them on the right VLANs. You can run DHCP on the Cisco 2821 for both the VLANs. Now just configure your wireless routers with relevant SSIDs and off you go. 

Now for the difficult part. You can either of the two options:

1. QoS Shaping. Configure two policy maps, shape them to the bandwidth you want to allow for that VLAN to use and apply on the subinterfaces.

2. I think you should also be able to use rate limit command on the subinterfaces but I am not sure. Give that a try as well.

Let us know how you go.

-Jay

[Aerone803]

Well,  the NME-16ES-1G module can actually be installed right into the router, giving me 16 more ports to use. However my issues are that these ports aren't like the other gigabit ports as I hear these ports on the NME-16ES-1G are switch ports, and may or may not be able to be a L3 routed port. I mean I could just stick the modem into gi0/0 and the gi0/1 into the wifi router that won't be my guest network. Then I could plug the guest network wifi router into the NME-16ES-1G interface, even if I need to use a vlan to assign a port an ip address. However I'm just not sure if it will work like that. 

[devils_advocate]

You can create Vlans on the router and use SVI interfaces instead of Routed ports.

I can't remember off the top of my head whether your module supports this but you using the no switchport command on the L2 module interfaces which will make them L3 ports with the ability to assign an ip address. 

[Aerone803]

Yeah, I'm just making sure that either way it goes, I should be able to get the NME-16ES-1G or the NM version and connect an end user wifi router to it without any trouble. 

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages wha2tsoever (including, without limitation, damages for loss of use, data or profit) arising  out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

BTW, if you can connect your router to a switch that supports VLAN trunking, you can run multiple logical interfaces across one physical interface.

Regarding using a switch module, most only support L2.  However, you can define a SVI and run the SVI as a L3 interface.

[Aerone803]

And if the switch port I install into the router is capable of L3, it should work just like any other port right?

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages wha2tsoever (including, without limitation, damages for loss of use, data or profit) arising  out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

I recall (?) SVIs on the ISRs might not support everything a true routed port does.

One issue, often you won't get the same level of performance as the built-in routed ports.  However, that's more often tied to using a HWIC port (even a 1 or 2 port routed port) vs. using ports off the NM.

[edit]

Forgot to mention, there are NMs that do provide L3 switch ports, basically those modules are a miniature 3750 L3 switches.  Again, most others are just L2 switch ports and require a SVI for L3.  With those if you only assign one switch port to a VLAN, it comes closest to being a routed port.

As above, there are also HWIC routed port modules (and L2 port HWIC modules).  The HWIC routed ports module ports have all the features of the built-in ports.

[Aerone803]

From my understanding, the NME-16ES-1G should also be able to run a L3. Either way, I won't run into any issues if I use a switch port, vlan or not, right? And by issues I mean... I should be able to link an end user wifi router(tp link) to it and it will function normally. 

[Jay Lohano]

Hi Aerone,

The NME-16ES-1G is a layer 2 switch module. The only way you can make it work in your situation is by thinking of it as a layer 2 switch and configure it as "router on a stick" configuration. You can create SVIs on the router, create a trunk from router port to the switch port, create vlans, associate switch ports in those vlans, connect your wireless bridge to the respective switch ports and verify connectivity.

-Jay