:original_name: er_01_0005.html

.. _er_01_0005:

Functions
=========

An enterprise router provides the functions listed in :ref:`Table 1 <er_01_0005__table10511144911816>`, allowing you to:

-  Manage attachments, custom route tables, associations, propagations, and routes.
-  Manage permissions, tags, and quota to improve service security.

.. _er_01_0005__table10511144911816:

.. table:: **Table 1** Functions of an enterprise router

   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Function              | Description                                                                                                                                                                                                                                           | Reference                                          |
   +=======================+=======================================================================================================================================================================================================================================================+====================================================+
   | Enterprise routers    | An enterprise router is a high-performance centralized router that supports route learning. When creating an enterprise router, you can set parameters such as its region, AZ, and name.                                                              | :ref:`Creating an Enterprise Router <er_01_0069>`  |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | After an enterprise router is created, you can still change its parameters based on service requirements.                                                                                                                                             |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Attachments           | You can attach network instances to the enterprise router.                                                                                                                                                                                            | :ref:`Attachment Overview <er_01_0019>`            |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | Network instances are attached to the enterprise router in different ways.                                                                                                                                                                            |                                                    |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | -  VPCs are attached to the enterprise router on the Enterprise Router console.                                                                                                                                                                       |                                                    |
   |                       | -  Virtual gateways are attached through the Direct Connect console.                                                                                                                                                                                  |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Route tables          | Route tables are used by enterprise routers to forward packets. Route tables contain associations, propagations, and routes.                                                                                                                          | :ref:`Route Table Overview <er_01_0024>`           |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | An enterprise router can have multiple route tables. You can associate attachments with different route tables to enable communication or isolation between network instances.                                                                        |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Associations          | Associations are created manually or automatically to associate attachments with enterprise router route tables.                                                                                                                                      | :ref:`Association Overview <er_01_0030>`           |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | -  Manually: Select a route table and create an association for an attachment in the route table.                                                                                                                                                     |                                                    |
   |                       | -  Automatically: You just need to enable **Default Route Table Association** and specify the default route table. The system automatically creates an association for an attachment in the default route table.                                      |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Propagations          | A propagation is created manually or automatically to enable an enterprise router to learn the routes to an associated attachment.                                                                                                                    | :ref:`Propagation Overview <er_01_0035>`           |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | -  Manually: Select a route table and create a propagation for an attachment in the route table.                                                                                                                                                      |                                                    |
   |                       | -  Automatically: You just need to enable **Default Route Table Propagation** and specify the default route table. A propagation is automatically created for an attachment in the default propagation route table.                                   |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Routes                | A route consists of information such as the destination address, next hop, and route type. There are two types of routes:                                                                                                                             | :ref:`Route Overview <er_01_0040>`                 |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | -  Propagated routes                                                                                                                                                                                                                                  |                                                    |
   |                       | -  Static routes                                                                                                                                                                                                                                      |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Sharing               | You are the owner of the enterprise router, and other accounts are the users of your enterprise router.                                                                                                                                               | :ref:`Sharing Overview <er_01_0095>`               |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | After you share your enterprise router with other accounts, these other users can attach their network instances to your enterprise router, so that their network instances can access your enterprise router.                                        |                                                    |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | This allows VPCs in the same region but different accounts to be attached to the same enterprise router.                                                                                                                                              |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Flow logs             | The flow log function records traffic logs of attachments on enterprise routers in real time. The logs allow you to monitor the network traffic of attachments and analyze network attacks, helping you achieve efficient O&M.                        | :ref:`Flow Log Overview <er_01_0108>`              |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | Flow logs can capture traffic of the following types of attachments:                                                                                                                                                                                  |                                                    |
   |                       |                                                                                                                                                                                                                                                       |                                                    |
   |                       | -  VPC                                                                                                                                                                                                                                                |                                                    |
   |                       | -  Virtual gateway                                                                                                                                                                                                                                    |                                                    |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Monitoring            | You can use Cloud Eye to monitor the network status of enterprise routers and their attachments.                                                                                                                                                      | :ref:`Supported Metrics <er_01_0103>`              |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Auditing              | You can use Cloud Trace Service (CTS) to record operations associated with your enterprise routers for future query, audit, and backtracking.                                                                                                         | :ref:`Key Operations Recorded by CTS <er_01_0091>` |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Tags                  | Tags are used to identify cloud resources. You can add tags to enterprise routers and route tables.                                                                                                                                                   | :ref:`Overview <er_01_0049>`                       |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+
   | Quotas                | Quotas can limit the number or amount of resources available to users, for example, how many enterprise routers can be created, how many attachments can be created for each enterprise router, and how many routes can be added to each route table. | :ref:`Overview <er_01_0056>`                       |
   +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------------------------------------+