Route Overview

What Is a Route?

Routes are used to forward packets. A route contains information such as the destination, next hop, and route type.

You can create a propagation for attachments to automatically propagate routes to route tables or manually add static routes to route tables.

Figure 1 Propagated routes and static routes

**Table 1** Route types
Route Type	Description	Attachment Type	How to Create	Description
Propagated routes	Propagated routes are routes that attachments propagate to the route tables of the enterprise router. They cannot be modified or deleted.	VPC Virtual gateway Peering connection VPN gateway Global DC gateway CFW instance	To create a propagation, see Creating a Propagation for an Attachment in the Route Table.	Routes are classified into propagated routes and static routes. The routes shown in Figure 1 are described as follows: Propagated routes are from: Propagations automatically created in the default route table of the enterprise router for attachments, such as peering connection 2, virtual gateway 1, VPN gateway 1, and VPC 1 attachments. Propagations manually created in the custom route table of the enterprise router for attachments, such as virtual gateway 1, VPC 1, VPN gateway 2, and virtual gateway 2 attachments. Static routes are manually added to the custom route table of the enterprise router for attachments, such as VPC 2 and peering connection 3 attachments.
Static routes	Static routes are manually created and can be modified or deleted. Static routes are classified into common routes and blackhole routes. A blackhole route only has a destination and has no next hop. It drops all traffic sent to the specified destination.	VPC Peering connection CFW instance	To create a route, see Creating a Static Route.

Route Priority

If there are multiple routes with the same destination but different targets in a route table, the route priority is as follows:

Static route > Propagated route for VPC attachment = Propagated route for CFW instance attachment > Propagated route for virtual gateway attachment = Propagated route for global DC gateway attachment > Propagated route for VPN gateway attachment > Propagated route for peering connection attachment

Static routes are manually configured and the destination of each static route must be unique in a route table.
Propagated routes are automatically learned by the system and may have the same destination in a route table.
A static route and a propagated route may have the same destination in a route table.
If the destinations of different routes overlap, the longest prefix match routing is used. The route that has the longest subnet mask and is the most specific of the matching table entries is preferentially used to determine the next hop.
For example, if the destination of traffic is 192.168.1.12/32, the destination of one route is 192.168.0.0/16 with a VPN attachment as the next hop, and the destination of another route B is 192.168.1.0/24 with a VPC attachment as its next hop, the traffic preferentially matches the route with the VPC attachment as the next hop.

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