BGP and Anycast

BGP is a technology that is generally used in IDC multi-line computer rooms, that is, the integration of multiple lines connected to the computer room. Realize multi-line single IP. Because the earliest multi-line computer rooms are dual-line and dual-IP, now many dual-line computer rooms begin to use this technology, making it easier for users to operate when using IP.

Anycast technology has the following advantages:

1. Different clients will access different destination hosts, This process is transparent to the client, thus realizing the load balancing of the destination host;

2. When the network connected to any destination host fails, causing the destination host to be unreachable, the client request can be automatically processed without human intervention. Routing to the nearest destination host currently reachable provides redundancy for the target host to a certain extent;

3. When the destination host is under DoS attack and cannot be reached, the client request will also be routed to other destinations due to the unreachable network On the host, and during a DDoS attack, due to the load balancing effect of Anycast, it avoids a single destination host from bearing all attack traffic, so it improves the security of the destination host to a certain extent;

Fourth, because Anycast uses routing metrics to "closest" "The destination host,which improves the client response speed.

However, the Anycast technology also has certain limitations:

the shared unicast address in Anycast cannot be used as a client to initiate a request, because the response to the request may not necessarily be returned to the initiated Anycast unicast address. Therefore, currently Anycast is only suitable for some specific upper-layer protocols. From the current practical application, the most extensive application of Anycast is the deployment of DNS.