|Prvý link na googli https://www.networkworld.com/article/2233273/cisco-subnet/understanding-4-byte-autonomous-system-numbers.html
Quote: › If a neighbor is Old-BGP, it either responds that it does not support the 4-byte ASN capability or does not respond to the Capability advertisement at all. In this case, the New_BGP neighbor can still bring up a session with the Old-BGP neighbor, but cannot advertise its 4-byte ASN. The neighbor wouldn’t understand it. Instead, New_BGP uses a reserved 2-byte ASN, 23456, called AS_TRANS (AS_TRANS is easily remembered because of its 2-3-4-5-6 sequence). This AS number is added to the My Autonomous System field of the Open message. Because AS_TRANS is reserved, no Old_BGP speaker can use it as its own ASN; only New_BGP speakers can use it.
Interoperable peering, then, is achieved because the New_BGP speaker “knows” its neighbor is an Old_BGP speaker and adapts to it; the Old-BGP speaker simply continues using legacy BGP rules.
Chápem ale tvoje obavy. Ak by to robila podobná banda, aká stojí za novým SK-NIC (alebo vlastne aj za tým starým), dopadlo by to tak ako hovoriš. Ak nie horšie.