An Express Connect router (ECR) supports both equal-cost multi-path (ECMP) load balancing and nearby forwarding modes. The default forwarding mode is ECMP load balancing. If multiple Express Connect circuits in the same region connect to different access points, the ECMP load balancing mode distributes traffic across multiple paths, and the nearby forwarding mode forwards traffic over the optimal path to achieve low latency.
ECMP load balancing mode (default)
The ECMP load balancing mode distributes packets across multiple equal-cost paths, implementing load balancing. This effectively prevents congestion on a single path and improves the efficiency of network resource usage and service stability.
For more information about how to use Express Connect circuits and an ECR to establish active/active connections between a data center and Alibaba Cloud, see Establish active/active connections between a data center and Alibaba Cloud by using an ECR.
Nearby forwarding mode
The nearby forwarding mode forwards traffic over the optimal path. This minimizes traffic detours and reduces latency in traffic transmission.
Contact your account manager to obtain the mappings between zones and access points.
If one of the two paths available in nearby forwarding mode is disconnected due to a fault, nearby forwarding automatically becomes invalid. All traffic is switched from the faulty path to the other path.
If a zone does not have a nearby access point, traffic is still forwarded in ECMP load balancing mode.
If your Enterprise Edition transit router (TR) functions as a forwarding gateway in the cloud, you must create at least two zones in the region in which the TR resides before you create a virtual private cloud (VPC) connection to the TR. This minimizes traffic detours between the VPC and the Enterprise Edition TR, achieving lower transmission latency and higher performance. For more information, see Announcement: Optimization on VPC-connected Enterprise Edition transit routers and Scenario 1: Your data center needs to communicate with multiple VPCs in the same area, and the VPCs need to communicate with each other.
Procedure
Contact your business manager to obtain the location of the data center in which your cloud resources are deployed.
Contact your business manager to obtain the access points for Express Connect circuits in the data center.
Connect to the corresponding Alibaba Cloud data center by using Express Connect circuits from the access points. For more information, see Connect to Alibaba Cloud over a dedicated Express Connect circuit and Overview of hosted connections.
Create Express Connect circuits and virtual border routers (VBRs), and configure Border Gateway Protocol (BGP). For more information, see Create and manage a dedicated connection over an Express Connect circuit and Create and manage a VBR.
Create an ECR and associate it with the corresponding VBRs and VPC. For more information, see Create and manage an ECR.
Change the forwarding mode
Log on to the Express Connect console.
In the left-side navigation pane, click Express Connect Router (ECR). On the Express Connect Router (ECR) page, find the ECR that you want to manage and click the name of the ECR. The details page of the ECR appears.
In the Basic Information section, click Edit next to Forwarding Mode.
In the Edit Forwarding Mode among Regions dialog box, select ECMP Load Balancing or Nearby Forwarding and click OK.
References
DescribeExpressConnectRouterInterRegionTransitMode: queries the cross-region forwarding mode of an ECR.
ModifyExpressConnectRouterInterRegionTransitMode: modifies the cross-region forwarding mode of an ECR.