I am trying to collect information about using RFC 1918 space on an ISP
backbone. I have read the RFC several times, and I don't see where it
says that you cannot use 10/8 space to number your backbone links (/30s).
I know this is an old thread that has been rehashed several times, but can
anyone please send me links or information that I can use to convince my
boss that we should use our arin alloc'd space on our backbone instead of
using private space.
Also if anyone has opinions on naming conventions for backbone such as why
to or why not to even have dns resolution for your backbone and some
conventions please let me know.
Private hosts can communicate with all other hosts
inside the enterprise, both public and private. However, they cannot
have IP connectivity to any host outside of the enterprise.
All other hosts will be public and will use globally unique address
space assigned by an Internet Registry.
Then you have the policy that its best to filter any rfc1918 packets ingress
which then leads on to broken path mtu, missing traceroute hops... etc..
for the tiny number of addresses you need on p2p why does your boss care.
Generally it is not prohibited by the RFC, but it is bad form if you send
out ICMP that originates from 10space to places outside your network.
As such, it's generally bad form to use these numbers on intefaces in the
backbone, since those interfaces are likely to show up in ICMP time exceeded
messages unless you completely block traceroute through your backbone, which
is generally regarded as far worse form.
Looking at the categories of hosts in the rfc, it would be my opinion that a
router that connects you to the outside world would fall into category3 and
therefore need globally unique space. Just my opinion for the day. Most
people frown heavily upon traffic that goes from one public node to another
crossing rfc1918 space, there were many threads in years past about @HOME's
use of this tactic.
Usually numbering backbone routers with a 10/8 is not a necessary practice.
Any backbone routers communicating with the outside world are marked category
three and should have globally unique IP numbers. Plus, if you are an ISP (in
which it looks like you are..), it will help others on public internet to try
to track down abuse a little deeper through traceroutes, which will may be
help them identify the upstream provider of the offender.
You could also use RFC1918 numbers for your point-to-point /30 aggregation
blocks with the customers.. But.. since that would have effect on customer's
premise equipment, it would be better to give them globally unique space as
well, who knows if your customer comes back and yells at you for not being
able to get to his router's serial interface IP.
You could also use RFC1918 numbers for your point-to-point /30 aggregation blocks with the customers.. But.. since that would have effect on customer's premise equipment, it would be better to give them globally unique space as well, who knows if your customer comes back and yells at you for not being able to get to his router's serial interface IP.
This practice was implemented here in the early days, before I came along. There have been almost no requests to change by clients, and very, very few who even noticed/cared enough to ask why.
But as more VPNs are deployed, I've seen this break some implementations. So for two reasons we've begun the (large) task of renumbering all the /30 ptp links either public or unnumbered:
1) Ensures all clients who decide to implement VPN don't run into frustration because of this practice. We want to encourage better security practices, and VPN can be an integral part of that.
2) The script kiddies won't mistakenly assume that we're not doing source address filtering. I'm sure that seeing a private address in traceroute probably makes you a more desirable target in certain circles.
There is only one case where I would recommend using a private address on a public link. We have a client periodically attacked, and in some cases the attackers have simultaneously attacked our own infrastructure. They now have only one path to them here, and every hop past the border is RFC1918.
I am trying to collect information about using RFC 1918 space on an ISP
backbone. I have read the RFC several times, and I don't see where it
says that you cannot use 10/8 space to number your backbone links (/30s).
As mentioned, routers tend to be seen as 'category 3' devices. See also
second and 3rd para on page 4.
I know this is an old thread that has been rehashed several times,
but can anyone please send me links or information that I can use to
convince my boss that we should use our arin alloc'd space on our
backbone instead of using private space.
If you are indeed a leaf-node, enterprise network your boss may be
right. There are ways to do things with unnumbered links too. But
how important is being able to diagnose and repair problems quickly?
The more complex the network is, the more fragile it is and the longer
your boss' boss will be yelling at your boss to yell at you to get it
fixed.
I prefer to just use /31s (see rfc3021) - the 'wasted address space'
whine evaporates.