Oddly, this guide suggests adding the PS3 to a DMZ *AND* setting up port-forwarding.
This is exactly right, and it exposes a major bug/flaw in most home-grade routers. Specifically, in a home-implementation a DMZ is not a DMZ. In the home implementation, the DMZ host is only outside of the SPI firewall; it does NOT have all ports open - as would be the case in a commercial DMZ implementation. All DMZs are not equal. The vendors are just protecting users from themselves.
From the other end of the problem, if you have only configured port-forwarding, but your machine is not in a DMZ I.E. still behind the router firewall, you'll still suffer very bad lag, but this time from the SPI firewall tracking the vector of each external packet.
I suffered terribly with lag with my PS3 only being in a DMZ - to the point I *never* saw my bullets hitting an enemy while watching their kill-cam view. In their kill-cam I look like, I'm just sitting there like a monkey appearing not to even fire - whereas from my in-game perspective, I emptied a whole mag and they still just killed me by magic!
After adding the PS3 to both the DMZ and configuring static port-forwarding as per the above link, I see my bullets raining down on the enemy for the first time while watching their kill-cam - the game is now fair and working for the first time!
This works, this is *the* fix, well done Treyarch, I can finally play your game as you intended and not sit there like a moron!
As it is so counterintuitive to implement a DMZ host and port-forwarding, I suspect the barrage of criticism Treyarch receive is likely due to the fact 95% of home-router vendors are being over-careful, and more effort needs to be done to inform all users - such as a message-of-the-day actually in game, and some kind of test-server to enable PS3 users to actually measure their lag stats/validate the configuration. Seeing your own bullets hitting the enemy for the first time is a very deterministic test, it's not an absolute measurement, which would be more useful.
I can only surmise that the port PnP stuff isn't implemented in the PlayStation and/or BO2 correctly as that *should* open all the ports the game requires when the PS3 is in the DMZ. Maybe that's the true root-cause.
I can now snap-shoot close range with SMGs for the first time since the game was released and actually win the 'draw' rather than die 100% of the time. This makes the game very deterministic and consistent from one match to the next.
Also, as an English resident, I'm getting added to USA matches for the first time in 3000+ games. This proves this change is radical.
Router (Linksys) Cisco E4200, firmware 1.0.05.
I can also regress this change by turning off static port-forwarding rules, which proves it's a true fix and not a fluke coincidence.