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Loopback Address Management

I'm about to start implementing loopback interfaces and /32 addresses for monitoring and management purposes. My question is what to do about address management. If I assign /32 addresses to each device I can see my routing tables growing quite large, if I summarize them to a /24 and advertise one /24 per site would I not be wasting alot of addresses?

Say I have a site with 10 devices, each with /32 Loopback addresses, and then I summarize this as a /24 across the WAN, I'd be wasting alot of addresses that way.

Does anyone have any suggestions on how to handle this? I find it odd that something that feels pretty crucial, such as management of devices has hardly any published case scenarios or best practices. I can't find much information at all on the subject. Any help would be greatly appreciated.

Robert

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Re: Loopback Address Management

robert.juric wrote:

I'm about to start implementing loopback interfaces and /32 addresses for monitoring and management purposes. My question is what to do about address management. If I assign /32 addresses to each device I can see my routing tables growing quite large, if I summarize them to a /24 and advertise one /24 per site would I not be wasting alot of addresses?

Say I have a site with 10 devices, each with /32 Loopback addresses, and then I summarize this as a /24 across the WAN, I'd be wasting alot of addresses that way.

Does anyone have any suggestions on how to handle this? I find it odd that something that feels pretty crucial, such as management of devices has hardly any published case scenarios or best practices. I can't find much information at all on the subject. Any help would be greatly appreciated.

Robert

Robert

If you are using private RFC 1918 addressing which i suspect you are then worrying about wasting addresses is nowhere near as important as if you were using public addressing.

Having said that there is nothing to stop you advertising a /25 or a /26 or a /27 etc.. So calculate the number of loopbacks you need per site and then choose the smallest subnet that will give you that many addresses eg. your site with 10 devices would need a subnet of 255.255.255.240 which gives you 14 useable addresses + broadcast.

Jon

Cisco are currently donating money to the Haiti earthquake appeal for every rating so please consider rating all helpful posts.

New Member

Re: Loopback Address Management

I see. I guess my coworkers have tried in the past to group our subnets by company division, which has left a lot of gaps in our schema. Trying to plan around this type of thinking has caused me a lot of headache. If we just contiguously assign addresses it would make life much more simple.

Thanks again Jon, you've been a great help lately.

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