[nsp] /30 over WAN links

[Lindahl, Carl]

Time Warner Cable (RoadRunner) Does it.



traceroute to xxxx, 30 hops max, 40 byte packets
1 10.219.16.1 (10.219.16.1) 7.941 ms 7.950 ms 7.733 ms
2 24.218.191.245 (24.218.191.245) 7.976 ms 8.050 ms 8.137 ms
3 24.62.0.222 (24.62.0.222) 10.782 ms 8.273 ms 9.598 ms
4 * * *
5 192.5.89.202 (192.5.89.202) 15.510 ms 13.641 ms 14.332 ms
6 128.197.254.125 (128.197.254.125) 13.888 ms 14.332 ms 14.109 ms





-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net]On Behalf Of Chris Stone, MCSE
Sent: Friday, February 06, 2004 2:58 PM
To: cisco-nsp at puck.nether.net
Subject: RE: [nsp] /30 over WAN links


 Seems to me I saw something not too long about about Sprint (I believe)
using private net address for WAN interfaces like this to combat DoS
attacks. I mostly use public address space (/30's), but have in the past
used private net address and it presents no problems. You just cannot ping,
traceroute, etc to those interfaces from the outside world...

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Roman Volf
Sent: Friday, February 06, 2004 12:34 PM
To: limmer at core.com
Cc: cisco-nsp at puck.nether.net
Subject: Re: [nsp] /30 over WAN links

Does anyone out there use private RFC1918 address for PTP links? Does 
this break anything?


Roman

Steve Lim wrote:

> Ah good question. And I think the question actually led me to an 
> answer to my initial queries.
>
> I suppose if we think long term, where customers might have changes in 
> needs, it would make sense to number the WAN links with /30s. How 
> messy would it be, if you began with a /29 or /28 over the WAN, and 
> the customer's needs calls for more IPs? Worse, what if we started 
> with a /27, and the customer downsized? What's the next move? Renumber 
> to a preferred prefix? Sucky. Perhaps routing additional subnets would 
> make sense, if you started of with a /29, and needed more. But on the 
> converse, renumbering a /29 to a /30 because the customer has no need 
> for the extra IPs, isn't the best idea. Especially if DNS and Email 
> servers are on those IPs.
>
> So, I am concluding that if I number the WAN with the most efficient 
> subnet (a /30), I now have the option to add or subtract any size 
> subnet per static routing. Simple, uncomplicated.
>
>
> Many thanks all for the comments.
>
> SL
>
> Rubens Kuhl Jr. wrote:
>
>> Any scenario that would require or prefer numbered links nowadays ?
>>
>>
>> Rubens
>>
>
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