Hi All, so i've read about singtel ONR double NATing issue and I realised that I've been double NATing for the past 1 year. Question is, is it really that bad to have a private network within a private network? Network has been stable for me. From what I've gathered online it only becomes an issue with UPNP and maybe VPN? portforwarding and some online games that use P2P connections. Although not many games continue to do P2P anymore. My singtel contract has expired and since we are shifting house, we are relocating it to the new home.
Alternatively, we could sign up for a new plan. Starhub seems to offer an equivalent 500mbps with the same price. M1 does as well, but once you factor in their installation charges, fibre registration charges, etc it becomes more expensive.
NAT causes a performance bottleneck and breaks certain applications. There are workarounds for some of the broken things (eg UPNP, port forwarding etc) which often only work through a single layer of NAT.
A lot of things work better without NAT, but will transparently degrade in the presence of NAT so the user is less likely to notice - ie things will still work, but performance will be degraded. Things like p2p applications (gaming, voice/video calling, torrents etc) often fit into this category.
Widespread use of NAT also stifles innovation, for instance there are a LOT more protocols than just TCP/UDP, but they are rarely used because whereas a normal router does not care about higher level protocols, a NAT gateway will only forward protocols it has explicit support for. For instance there is a protocol called SCTP which unlike TCP has support for native multi pathing (ie using 2 connections at once, aggregating the throughput and transparently continuing to work if one fails - think of a mobile phone with both wifi and mobile data).
In general NAT is not something you want, it's something you are forced to live with because you don't have enough IP addresses to give one to each device. That's why NAT is almost never used with IPv6, it's technically possible but since it isn't necessary you'd only experience the negatives.
