Tham khảo tài liệu 'routing 3', công nghệ thông tin, chứng chỉ quốc tế phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Large-Scale BGP 287 r ample 3-147 After the neighbor remove-private-AS Command Has Been Added to Idaho s BGP Configuration the Private AS Numbers of AS 100 s Client Autonomous Systems Are Hidden from Austria Austria show ip bgp BGP table version is 214 local router ID is Status codes s suppressed d damped h history valid best i internal Origin codes i - IGP e - EGP . - incomplete Network Next Hop Metric LocPrf Weight Path 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 100 i 24 0 0 100 i 24 0 32768 i 24 0 32768 i 24 0 32768 i Austria Case Study BGP Confederations BGP confederations make large transit autonomous systems more manageable by enabling the administrator to break the AS into subautonomous systems. The subdivided AS itself becomes the confederation and the subautonomous systems are the member autonomous systems. Autonomous systems outside of the confederation see the entire confederation as a single AS and do not see the member autonomous systems. Because the member autonomous systems are hidden from the outside they may use either public or private AS numbers although best practice suggests using private AS numbers. The advantage of confederations is that they sharply reduce the number of IBGP peering sessions. IBGP is used normally within each member AS but a special version of EBGP known as confederation EBGP is run between the autonomous systems. No IBGP sessions are configured from a BGP speaker in one AS to a BGP speaker in another AS within the confederation. Figure 3-28 shows an example of a confederation. AS 1200 has been subdivided into three confederation autonomous systems AS .
