How many BLB instances can a user create at most?

Currently, a user supports the creation of a maximum of 60 BLB instances. If you need to create more instances, you are welcome to apply by Ticket.

Does BLB limit bandwidth?

The BLB instance itself has no bandwidth limitation; however, if you need a public network access, you need to bind EIP whose bandwidth ranges from 1 to 1,000 Mbps. Learn about EIP.

What forwarding rules does BLB support?

• The 4-layer (TCP、UDP) listener supports three forwarding rules: weighted round-robin, least connection and source IP;
• The 7-layer (HTTP protocol and HTTPS protocol) listener supports two forwarding rules: weighted round-robin and least connection.

What monitoring information does BLB currently provide?

• The 4-layer BLB provides listener-level incoming traffic from the external network, outgoing traffic to the external network, number of instances, network traffic, network packets, and number of active connections.
• The 7-layer BLB provides listener-level incoming traffic from the external network, outgoing traffic to the external network, number of instances, network traffic, network packets, number of active connections, and number of requests.

How does health check work?

BLB automatically shields faulty nodes through health checks to achieve high service availability. BLB's health check has two types: TCP protocol health check and HTTP protocol health check.

• The TCP protocol health check works by sending tcp syn packets;
• The HTTP protocol health check works by sending HTTP GET requests.

How do I get the real IP of the visitor?

• For the 7-layer (HTTP protocol and HTTPS protocol) listener, the feature of "Get Real Access IP" is enabled before the BLB service listening is configured, and can be obtained through HTTP Header: X-Forwarded-For.

Note: If the request header sent by the client to BLB already contains HTTP Header: X-Forwarded-For, the current processing logic of BLB will add a new HTTP Header: X-Forwarded-For in the request header. Therefore, there will be two HTTP headers:X-Forwarded-For in the header in the request with the latter one being added by BLB.

• For the 4-layer (TCP protocol) listener, you can obtain the real IP address of the visitor from the external network without any configuration. If the visitor is an intranet BCC, the real IP address of the visitor cannot be obtained for the time being.

Does BLB support keep session?

The 4-layer (TCP protocol) listeners can implement keep session through the forwarding rules of source IP; the 7-layer (HTTP and HTTPS protocols) listeners implement keep session by inserting/rewriting cookies.

Does the backend BCC need external network bandwidth? Is it related to BLB's service capabilities?

If the BCC is only connected through BLB, the BCC may have no public network bandwidth.

Does BLB have DDOS protection?

After the DDOS attack exceeds 5G, the EIP will be set by the network operator as a black hole, which cannot be unbound and inaccessible. The server itself can be used normally. The black hole is only the public network EIP on the BLB. DDOS defense recommends that you use a high-defense IP. Detailed Reference