Question: why ebgp ttl is 1?
Answer: By default, IOS sends BGP messages to EBGP neighbors with an IP time-to-live (TTL) of 1. ... The maximum value of the 8-bit TTL field in an IP packet is 255; instead of accepting only packets with a TTL set to 1, we can accept only packets with a TTL of 255 to ensure the originator really is exactly one hop away.