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ChefJay
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Location: Clearlake, CA, USA

Trouble Passing static IP's from ISP through RB1100 to 3rd party router

Tue Aug 31, 2021 2:26 am

Hello everyone,

Thanks for taking a look at my issue.

I've got an RB1100 setup with some public static IP addresses, I have a new large block of IP's from my ISP, but the I have to pass them through my RB1100 inorder for them to work. I'm not sure how to go about this with RouterOS. Any and all help would be great.

Basically we have a block of 5 public IP's, then we received a second block of IP's from the ISP, but the ISP says we have to pass them via layer 2 through our router to our tenants router that is connected to our Mikrotik.

I'm very lost.
 
joegoldman
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Re: Trouble Passing static IP's from ISP through RB1100 to 3rd party router

Tue Aug 31, 2021 7:27 am

There are many options - depending on how you want to use your resources.

You can setup a LAN, using gw address in the block and hand the rest out having all the 3rd party routers in that LAN

You can use a system like PPPoE and hand them out on the ppp interface

You can use private IP addresses to 'peer' and static route via that IP address

Or you can split your block up into smaller/tiny blocks (/30's) and use that - very wasteful on resources though.

Depends on how many IP's you got (What size subnet), how many customers you have, and if you expect it to grow.
 
sindy
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Re: Trouble Passing static IP's from ISP through RB1100 to 3rd party router

Tue Aug 31, 2021 9:57 am

the ISP says we have to pass them via layer 2 through our router to our tenants router that is connected to our Mikrotik.
Is that a contractual obligation that you must pass this whole block of IPs to this particular tenant, i.e. you have to serve as an extension of the ISP's network so that the ISP wouldn't have to install a dedicated physical link to the tenant? Or is it just an information from the ISP about how that block is being handled on their side, i.e. that they expect devices holding addresses from this block to respond to ARP requests sent by the ISP's router, and you are free to assign the addresses from that block to any tenants you may have?
 
ChefJay
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Posts: 40
Joined: Mon Mar 20, 2017 7:25 pm
Location: Clearlake, CA, USA

Re: Trouble Passing static IP's from ISP through RB1100 to 3rd party router

Wed Sep 01, 2021 3:04 am

There are many options - depending on how you want to use your resources.

You can setup a LAN, using gw address in the block and hand the rest out having all the 3rd party routers in that LAN

...
This seems like the best way to do this. So your saying I setup the VLAN gateway as the gateway address that was given to me by the ISP? This would basically make my Mikrotik a hop between the downstream router and the ISP's handoff, yes?
 
ChefJay
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Topic Author
Posts: 40
Joined: Mon Mar 20, 2017 7:25 pm
Location: Clearlake, CA, USA

Re: Trouble Passing static IP's from ISP through RB1100 to 3rd party router

Wed Sep 01, 2021 3:07 am

the ISP says we have to pass them via layer 2 through our router to our tenants router that is connected to our Mikrotik.
Is that a contractual obligation that you must pass this whole block of IPs to this particular tenant, i.e. you have to serve as an extension of the ISP's network so that the ISP wouldn't have to install a dedicated physical link to the tenant? Or is it just an information from the ISP about how that block is being handled on their side, i.e. that they expect devices holding addresses from this block to respond to ARP requests sent by the ISP's router, and you are free to assign the addresses from that block to any tenants you may have?
So we were originally given a block of 5 public static IP addresses. We have an EDGE Switch connected to our ISP's handoff and we have 5 different routers connected using those IP's. We now have need for more public IP's. We were then given a block of 5 more address, but we were told they have to be connected behind one of our routers using the current block of 5 static's we have.

I'm just not sure how to setup my Mikrotik (that's using 1 of the original 5 static IP's from my ISP) so that a router behind it can use one of the second blocks of static IP's.

The ISP tells me that we need to setup our Mikrotik as a hop for the second set of IP's.
 
sindy
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Re: Trouble Passing static IP's from ISP through RB1100 to 3rd party router

Wed Sep 01, 2021 12:49 pm

Assuming that your original "block of 5 addresses" is o.o.o.0, your 1100's own address on the ISP-facing interface is o.o.o.6, and the new "block of 5 addresses" (actually, 8 addresses if you don't waste them inefficiently) is n.n.n.0/29:

ISP's hypothetical Mikrotik:
/ip address
add interface=ether-to-ChefJay address=o.o.o.1/29
/ip route
add dst-address=0.0.0.0/0 gateway=?.?.?.?
add dst-address=n.n.n.0/29 gateway=o.o.o.6


Your 1100:
/ip address
add interface=ether-to-ISP address=o.o.o.6/29
add interface=ether-to-tenant address=100.64.0.1/30
/ip route
add dst-address=0.0.0.0/0 gateway=o.o.o.1
add dst-address=n.n.n.0/29 gateway=100.64.0.2


Tenant's hypothetical Mikrotik:
/ip address
add interface=ether-to-ChefJay address=100.64.0.2/30
/ip route
add dst-address=0.0.0.0/0 gateway=100.64.0.1


The above way, you've transparently handed over all the 8 addresses to the single tenant, and it is their job how they use them.

If you want to allocate to a given tenant only several addresses from the /29, the setup at the 1100 will be the same, except that you'll use one route per each /32 address, or possibly one route with a /31 destination prefix for two adjacent addresses or a /30 one for four. But the tenants will have to handle the addresses carefully, i.e. they will not be able to handle them as subnets as 3 IP addresses are "wasted" for a subnet. That's why a /29 is perceived as a "block of 5 addresses" although all 8 can be used if things are done slightly more carefully.

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