SKFREE

SKFREE Pokec - 2byte vs. 4byte ASN

PCnity - 07.09.2017 - 18:40
Post subject: 2byte vs. 4byte ASN
Hello,

Mam sprostu newb otazku:

Doteraz moje prefixy providerovi oznamujem cez privatne ASN a teda ich origin je provideorovo 16 bit ASN... Hrozi mi nejake riziko ak prejdem na vlastne 32b public ASN?

Moze sa stat, ze nejaky "mensi" ISP dakde v Cape Towne nebudu mat v BGPcku zaznam pre moj prefix, lebo by ich routre nevedeli 4B ASN? Alebo je to uplny nezmysel a nemam co riesit?

Kedze RIPE uz moc 16b ASN davat nechce, obzeral som sa po nejakom markete, ale nic som nenasiel. Je to no issue, albeo proste 4B ASN nemaju "hodnotu" na rozdiel od IPv4?

Dik.
backslash_ - 13.09.2017 - 22:55
Post subject:
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.
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