tailieunhanh - Mission-Critical Network Planning phần 10

Đây là lý do tại sao truyền dữ liệu không đồng bộ là đôi khi được gọi là bóng. Với truyền dữ liệu không đồng bộ, cập nhật cam kết tại các trang web chính kể từ khi thuế thu nhập cá nhân cuối cùng của vấn đề các nhân đôiTài liệu thực hành dành cho học viên | 370 Using Recovery Sites of networking with a recovery site. In this example the recovery site has a network presence on an enterprise WAN. In a frame relay environment the location could be connected using permanent virtual circuits PVCs . Routers are then configured with the recovery site address to preserve the continued use of the same domain names. This makes service seem available anywhere in the domain regardless of the physical location. Load balancing can be used to redirect and manage traffic between the primary and recovery sites enabling traffic sharing and automatic rerouting. Transparent failover and traffic redirection to the recovery site can be achieved in combination with domain name and Web infrastructure to ensure continuous Web presence. Ideally whether a user accesses a primary or recovery site should be transparent. Redirection of the domain to a different Internet protocol IP address can be done using some of the techniques discussed earlier in this book. Internet access to the recovery site can be realized through connectivity with the same ISPs that serve the primary site or an alternate ISP that serves the recovery site. Branch locations that normally access the primary location for transaction processing and Web access through a PVC could use virtual private network VPN service as an alternate means of accessing the recovery site. Automatic failover and redirection of traffic requires that data and content between the two sites be replicated such that the recovery site is kept up to date to take over processing. This implies that data and content must be updated at either the primary or recovery site implying bidirectional replication between the sites. Data replication should be done on an automated predetermined schedule if possible. Data should be instantaneously backed up to off-site storage devices as well. Active and backup copies of data should exist at both sites. As already mentioned a SAN can be good way to facilitate data .