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CDX54
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Route a single address

Thu Dec 01, 2011 4:11 am

I have a /28 block of public addresses and need to route some of them to internal routers. This is the topology:

x.177(cable modem)----x.178(mikrotik)---bridged network(on port ether2)---here is where I want to put x.y (x.179) on another mikrotik router.

How can I route a single public address without sub-netting, and losing half the addresses, my /24 block...

Thanks so much.

CW
Last edited by CDX54 on Fri Dec 02, 2011 6:42 am, edited 2 times in total.
 
pedja
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Re: Route a single address

Thu Dec 01, 2011 8:43 am

You cannot rute without subnetting. You may use dst-nat instead.
 
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dasiu
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Re: Route a single address

Thu Dec 01, 2011 8:51 am

Trying to understand... Where is the /28 subnet? Does the cable modem also have an IP address from the same /28 subnet? What is the gateway for the /28 addresses - is it still your device, or your provider's?
x.178 - is it configured in the same time on the mikrotik connected to gateway AND on "another mikrotik router"? (that's what diagram says...)
x.176 - is it IP address configured on cable modem?? x.176/28 is network address, not a device address. You have x.177-x.190 possible addresses

Or - in other words - is the /28 IP pool ROUTED to your network through DIFFERENT IP address on WAN?

If it is routed - You can try to route /32 address - by creating a PPP address (on first Mikrotik on ether2: address=192.168.0.1/32 network=x.178, on other Mikrotik: address=x.178/32, network=192.168.0.1)

If it is switched (the /28 is on WAN) - I would just bridge it through a vlan or vpls between the MTs.
 
CDX54
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Re: Route a single address

Fri Dec 02, 2011 6:41 am

dasiu,

Thank you for your reply. First things first, I corrected the diagram:

x.177(cable modem)----x.178(mikrotik)---bridged network(on port ether2)---here is where I want to put x.y (x.179) on another mikrotik router.

(The gateway / cable modem is x.177, the second router should have been x.179 the next address in the block)

Next, as above the gateway is x.177, after reading through your post I realized my error. So when I entered it into the main mikrotik as such it shows up as a /32 not /28. Don't know if this helps any.
;;; WAN Public
-D		x.x.x.178/32	x.x.x.177	ether1-gateway


My usable address range is x.178-x.190 as per my ISP.

Now on the first question you have about the cable modem, it appears that its address is x.177 as when I tracert from the mikrotik in the above diagram to a server connected directly to the second port on the cable modem it goes hop 0 = x.177 hop 1 = x.180

The gateway is my providers near as I can tell. Which from what I understand you saying that means it is routed and I should be able to route /32 addresses out to other devices (routers, servers, etc)?

Thank you so much again, I am really starting to like networking / routing but it is kicking my behind trying to wrap my head around some of the concepts.

CW
 
CDX54
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Re: Route a single address

Wed Dec 07, 2011 1:45 am

I ended up just doing 1 to 1 nat for each address to an internal address. Works fine so far.

CW

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