30 May
2016
30 May
'16
3:01 p.m.
The basic idea would be that AMPR to AMPR traffic is a
go since it is
tunneled directly.
Public IP to AMPR is a no-go for tunneled networks.
They have a public Gateway IP anyway, so you should use that one for access
from the internet.
Marius, YO2LOJ
When you use Echolink from within AMPRnet but want to use a public IP you should
be very careful how to implement it. Some people configure an Echolink repeater
on an AMPRnet address and then route the traffic to some gateway where this address
is translated using NAT.
However, this does not work correctly! The Echolink repeater will register itself
with the Echolink system server which is on public internet, so the registration
address in the Echolink system is the address of your NAT router.
But internally, the repeater has a 44.x.x.x address so when someone from a 44.x.x.x
address connects the reply will come from the wrong address and the connection
does not go through.
This manifests itself when some other systems are natively on AMPRnet not using NAT.
For example, here in the Netherlands we have several repeaters with a true AMPRnet
address that is BGP routed, and we also run several Echolink proxies and relays
on AMPRnet addresses. In neighboring Germany, the NAT method is often used, where
the repeaters have a 44.x.x.x address but connect to the Echolink server via NAT.
As a result, no connections between the repeaters in these two areas are possible,
and worse: people using our Echolink proxies and relays cannot connect to German
repeaters or users.
It can be solved by not using NAT to translate the Echolink traffic to public
addresses, but instead run an Echolink proxy on the gateway system which converts
the internal AMPRnet address of the Echolink repeater to the public address of
the gateway. Unfortunately only a single proxy can be run per public IP address,
so a "normal" gateway with a single external address can only host a single
repeater.
To solve this, a number of proxies can be run e.g. in a datacenter where an IPv4
subnet is available for them (more and more difficult, of course!).
This has now been done in Germany.
The disadvantage of this solution is that all users that are on AMPRnet still connect
to the outside address. On a BGP routed AMPRnet network where no proxies or
translations are used, local users can connect the repeater directly.
Rob