On 7/28/21 4:14 PM, Janko Mivšek via 44Net wrote:
Rob PE1CHL via 44Net je 28. 07. 21 ob 14:40 napisal:
There is no need to explain that. I am fully aware which person on the TAC has come up with this shit and that it is only intended to fix his own broken network. All the others chime in that they have no issue and don't need any fix.
I really like to have an explanation of a statement that HAMNET is broken, and from both sides, from you Rob and from Jan DG8NGN as a HAMNET architect.
In my opinion, what is wrong with German HAMNET is the way it routes to internet.
There is no symmetric routing. The network is an island that can only be used as an intranet, and when traffic is destined towards the internet, it will be routed to some random nearby place where it traverses a home router towards internet, being NATted to the commercial IP of that home user. This causes problems with protocols like Echolink, because echolink tries to communicate two ways between IP addresses, and registers addresses in a central server. That of course will not work when there is NAT in place.
The network also has issues with its route tables. It does not route based on a single table with most-specific-subnet-first, but rather it has multiple tables which are examined sequentially. That means that you cannot route an entire country network one way, and some subnet another way, and have a predictable outcome.
Sometimes systems in the network are multi-homed (they have both a 44.x and a commercial IP address), but they lack the proper policy routing. So when you connect from a 44.x address to the commercial IP address of such a system, they route back over the AMPRnet because they only route depending on the destination of the packet, not depending on the local source. The proper way would be to route such traffic (with the commercial IP->44.x) directly to internet, while 44.x->44.x traffic is routed over radio.
These are all things that can be fixed internal to the network. The presence of a backbone network would make that easier, as this could be used to tie the whole German network to internet in a uniform way without NAT. It is then still their decision whether they want to do that bidirectionally for all traffic, or have built-in restrictions on incoming internet traffic.
Rob