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Network Infrastructure ISP questions

Question, trying to understand.  Scenario.  Have one isp with network isp router to our main site router.  Need another block of public addresses from ISP to assign to tenants on different floors, let’s say that block is  The tenants NEED static addresses.  This is hypothetical situation I am trying to understand.  See attachment for network map.

 So, two questions here:

  1. How does the isp get you that second block of addresses?  Do they just create a sub interface on their router for additional block?  I mean I know you can create sub networks on the interfaces but that would not allow you to subnet out the second ip block to be used for the tenants, correct?  I know you could add a layer 2 device between isp and main site router and directly plug in tenants there, but let’s assume there isn’t a layer 2 device.  I just want to know what the configs would need to be on the main site router and the isp router to allow that second network to be used for the tenants.
  2. If subnetting the to /29 I created 4 subnets, where they can be used for the four tenants listed below.  I would assume that I need VLANS in order to prevent one tenant from assigning an ip from another tenants subnet?



Hi bboklewski,See my

Hi bboklewski,

See my responses below:

1. I'm an ISP, I have single connection with customer. Customer needs more IP addresses. I just create a static: "ip route <you side of p2p>" I probably already have a redistribution policy for statics, I just add that into my prefix list and its goes up. You your main site router, you just need to add routing toward your tenant's next hops. Otherwise, if you use BGP, then you announce this new prefix like any other prefix...and insure you have routing toward your tenant's devices.

2. Yes. You need 4 VLANs if you need segmentation between tenants. What happens when your tenants need more IP addresses? If your ISP gives you IP space, then they do the static routing as outlined in 1. You then add a secondary IP address on your main site router's interface facing the tenants--the tenants deal with further routing. If you get your own IP space, then same thing applies, except with a BGP configuration as outlined in 1.



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