GCP provides two load balancers namely Network and HTTP(s) where the former works on layer 4 and the later works on layer 7.
There is also a documentation which states that even HTTP traffic can be load balanced by a network load balancer. This slightly confuses which load balancer to choose for a web app in GCP. It is better to understand the differences before selecting one for the project.
What are the differences between them based on the workflow, setup, region/zone based, options for session affinity, and other settings?
Network load balancer Vs HTTP(s) Load Balancer
+---------------------+------------------------------------------+------------------------------------------------------+
| Category | Network Load Balancing (NLB) | HTTP(S) Load Balancing (HLB) |
+---------------------+------------------------------------------+------------------------------------------------------+
| 1. Region / | NLB supports only within a region. | HLB supports both within cross-region |
| Cross-Region | Does not support cross-region | load balancing. |
| | load balancing | |
+---------------------+------------------------------------------+------------------------------------------------------+
| 2. Load balancing | NLB is based on IP address, port | HLB is based only on HTTP and HTTPS |
| based on | and protocol type. Any TCP/UDP | protocols. |
| | traffic, even SMTP can be | |
| | load balanced. | |
+---------------------+------------------------------------------+------------------------------------------------------+
| 3. Packet | Packet inspection is possible and | HLB cannot inspect packets. |
| inspection | load balance based on packets | |
+---------------------+------------------------------------------+------------------------------------------------------+
| 4. Instance | No need of creating instance group. | Managed / UnManaged Instance group |
| Group | Target pools need to be created. | is necessary for creating HTTP / HTTPS |
| | Instance can be just tagged to the pool. | load balancer. |
| | Ideal for unmanaged instance group | |
| | where instances are non homogeneous. | |
+---------------------+------------------------------------------+------------------------------------------------------+
| 5. Workflow | Forwarding rules is the starting point. | This is quite complex in HTTP(s) load balancer. |
| | It directs the request to the | Global forwarding rulesroutes direct the request |
| | target pools from which compute | to target HTTP proxy, which in turn checks the |
| | engines will pick the request. | URL map to determine appropriate backend |
| | | services. These services in turn direct the request |
| | Forwarding rules -> target pool | to the instance group. |
| | -> instances | |
| | | |
| | | Global forwarding rules -> Target HTTP proxy -> |
| | | URL map -> Backend Sevices -> instance group |
+---------------------+------------------------------------------+------------------------------------------------------+
| 6. Types of | Basic network load balancer which | 1. Cross-region load balancer uses only one |
| load balancer | directs the request based on IP address, | global IP address and routes the request |
| | port and the protocol within the region. | to the nearest region. |
| | | |
| | | 2. Content-based load balancer is based |
| | | on the URL path. Different path rules need |
| | | different backend services. for eg: /video |
| | | and /static require two separate backend services. |
+---------------------+------------------------------------------+------------------------------------------------------+
| 7. Session affinity | Session affinity can be set, but only | 1. Client IP Affinity: This directs the same |
| | during the creation of target pool. | client ip to same backend instance by |
| | Once it is set, the value | computing hash of the IP. |
| | cannot be changed. | 2. Generated Cookie Affinity: Load balancer stores |
| | | cookie in clients and directs the same client to |
| | | same instance with the help of retrieved cookie. |
+---------------------+------------------------------------------+------------------------------------------------------+
| 8. Health check | Health check is optional, but network | Health can be verified by either using HTTP |
| | load balancing relies on HTTP Health | heath check or HTTPS health check. |
| | checks for determining instance health. | |
+---------------------+------------------------------------------+------------------------------------------------------+
The above table is based on my perspective. If anything is incorrect or If I had missed something, please feel free to comment and I will add it to the table.
Here is the link for instructions on setting up an HTTP load balancer in GCP.
In addition, I would like to mention there are 3 main aspects to consider in choosing the correct Load Balancer (LB) in GCP:
1) Global versus regional
2) External versus internal
3) Traffic type
Please find more information on this chart as well.
来源：https://stackoverflow.com/questions/41535226/what-are-the-differences-between-network-and-https-load-balancer-in-gcp