From: Sean Donelan, Sent: Sunday, December 05, 1999 8:37 AM
For people with ultra-high reliablility requirements, a /19 isn't the solution.
But, from the discussion, a /19 would be part of the requirement, along with some form of LBDNS, like Resonate. Yes, the Net can get blackholed, but isn't that an error condition anyway? One that must be fixed? Also, we haven't discussed the security implications much. Keeping the rest of this in mind, those of us using tcp_wrappers, SSH, and other IP-based filtering, would have our lives simplified greatly if we had a common IP block that covered the entire domain, regardless of which provider a host is located in. VPNs would also be much less expensive to maintain. Simpler security == tighter security. The issue is that there is no way that the cases I have before me should need more than a /24, even if /20 requirements can be met by host count. Most of the hosts would be in NAT'd space anyway, for security reasons I shouldn't need to go into here. In fact, I could architect both domains into a /25, or even a /26, if I had to, using NAT'd space (it would be a tight fit with no growth allowance). To review the cases, I have two instances where I have geographically separated sites that need a common IP-block, with multiple providers. I have an interim solution now, using an SSH VPN, but the maintenance is killing me. Not to mention the fact that I still haven't reduced the packet load on the primary site. On one of the sites, distribution of the packet load is ONE of many reasons for the geo-physical separation. Ergo, that dog doesn't scale here. In fact, it could DOUBLE traffic at the primary site and add encryption processing load as well. As an aside, IPSEC (as one person had suggested) would not be an improvement, wrt packet traffic, at the primary site (while the implementation is slightly different, the general effects are the same). The only apparent route left would be to burn /24s at each end, even though I don't need them. I got no problem with that, but I thought that the priority goal was conservation of IP space. BTW, I obviously have sympathy for a movement that would generate an RFC for CONSISTENT route filtering policies.