Automatic Underlay Route Orchestration
In the CloudCampus Solution for network virtualization, the underlay network only needs to ensure Layer 3 connectivity, which can be implemented by configuring an Interior Gateway Protocol (IGP). OSPF is generally used on campus networks.
In Figure 1-10, all switches run OSPF, and the entire autonomous system (AS) is divided into three areas (areas 0, 1, and 2). Switch A and Switch B function as Area Border Routers (ABRs) and forward inter-area routes. After basic OSPF functions are configured, all switches should be able to learn routes to all network segments in the AS. The basic OSPF configurations include the ID of the VLAN to which each interface belongs, IP address of each VLANIF interface, OSPF function on each switch, and network segment of each area.
Manually configuring basic OSPF functions in traditional mode is inefficient. This is because a large number of OSPF items and interface IP addresses need to be configured. It takes a long time to log in to and configure switches one by one. In addition, configuring switches using command lines is error-prone and makes troubleshooting difficult upon faults. To address these issues, Huawei CloudCampus Solution for network virtualization provides the automatic underlay route orchestration function. With this function, iMaster NCE-Campus can automatically configure OSPF routes, divide OSPF areas, and deliver interface configurations based on the physical network topology. The physical network topology is imported to iMaster NCE-Campus based on the configuration plan or automatically learned by iMaster NCE-Campus.
Automatic underlay route orchestration falls in to single-area orchestration and multi-area orchestration, as shown in Figure 1-11.
When there are fewer than 100 switches in a network area where routes need to be deployed on the underlay network, single-area orchestration is recommended.
- All switches between the border and edge nodes on the fabric support automatic orchestration of OSPF routes. These devices refer to all aggregation and core switches if VXLAN is deployed across the core and aggregation layers, and refer to all core, aggregation, and access switches if VXLAN is deployed across the core and access layers.
- All switches between the border and edge nodes on the fabric are planned in area 0.
- Different VLANIF interfaces are planned on all switches for interconnection through OSPF. The interconnected Layer 2 interfaces allow packets from the corresponding VLANs to pass through.
- When configuring a fabric, you need to create loopback interfaces on the switches that function as border and edge nodes for establishing BGP EVPN peer relationships. Routes on the network segments where the loopback interface IP addresses reside are also advertised to area 0.
- If a Layer 2 switch is required for interconnection between the border and edge nodes and performs transparent transmission between them, this Layer 2 switch cannot be the core or aggregation switch. (When adding a switch to a site on iMaster NCE-Campus, you can set the switch role.) After the automatic OSPF route orchestration function is enabled, interfaces connecting this Layer 2 switch to the border and edge nodes allow packets from the corresponding VLAN to pass through.
When there are more than 100 switches in a network area where routes need to be deployed on the underlay network, multi-area orchestration is recommended.
- All switches between the border and edge nodes on the fabric support automatic orchestration of OSPF routes. These devices refer to all aggregation and core switches if VXLAN is deployed across the core and aggregation layers, and refer to all core, aggregation, and access switches if VXLAN is deployed across the core and access layers.
- The core switch is planned in area 0. Each downlink VLANIF interface on the core switch, as well as the aggregation and access switches connected to these VLANIF interfaces are planned in the same area.
- Different VLANIF interfaces are planned on all switches for interconnection through OSPF. The interconnected Layer 2 interfaces are added to the corresponding VLANs in trunk mode.
- On the core switch that functions as a border node, routes on the network segment where its loopback interface IP address resides are advertised to area 0. On an edge node, routes on the network segment where its loopback interface IP address resides are advertised to the area to which the edge node belongs.
- If a Layer 2 switch is required for interconnection between the border and edge nodes and performs transparent transmission between them, this Layer 2 switch cannot be the core or aggregation switch. (When adding a switch to a site on iMaster NCE-Campus, you can set the switch role.) After the automatic OSPF route orchestration function is enabled, interfaces connecting this Layer 2 switch to the border and edge nodes allow packets from the corresponding VLAN to pass through.