What is a Route Table; when do I need to change it for a vService or Backend Service?

Short answer

A Route Table is an isolated network domain within TR7 with its own interfaces, IP addresses, routes, firewall and default gateway (similar to VRF). In every setup, there is a DEFAULT table that cannot be deleted; if there is a single table, everything uses it and nothing needs to be changed. If the Backend Service can be reached only from the network of a table other than the default (e.g. if the network on which the vService is published and the network used to talk to the Backend Services are in separate tables), if a different exit path is required, or if networks (e.g. customers, environments) will be kept separate from each other, the Route Table field of the Backend Service or of the Network vService is changed.

How Does It Work?

• Each Route Table is a separate network domain; when an interface is moved to a table, its IPs and routes also go with it.
• Traffic in one table does not see the interfaces and routes of the other table. If communication between tables is required, a V-ETH (Peer) connection is established between them.
• Tables are added and managed from the Network → Route Tables screen.

Where Is It Selected in Load Balancer?

Object	Field	What it affects
Backend Service / Backend Group	Route Table (default DEFAULT)	TR7 connects to the Backend Service through the interfaces and routes of this table; health checks are also sent from this table. In the SNAT field, the Use Device IP and Health Check Source IP lists are limited to the IPs in this table; with SNAT Default, the source address is the Interface IP, on the same subnet as the server (or as the gateway, if the server is reached via a gateway), of the interface that goes to the server in this table.
Network vService	Route Table	The Frontend IP, SNAT IP and Backend Service lists are filtered according to this table. When the table is changed, the selected Frontend IPs, SNAT IP and Backend Services are cleared.
HTTP / L7 TCP vService	Frontend IP	Each Frontend IP is listened on in the table to which its own IP is bound; no separate selection is required.

The HTTP and L7 TCP vService form also has a Route Table field; this field appears only while QOS is on and more than one route table is defined, and it determines from which network domain the vService's log output is made.

When Is It Changed?

Your situation	What is done
There is a single Route Table (DEFAULT)	Nothing; it stays at the default
The network on which the vService is published (e.g. DMZ, the RT_DMZ table) and the network where the Backend Services are located (e.g. the server network, the RT_SERVER table) are in separate tables	The vService's Frontend IP is selected from the interface in the DMZ table; in the Route Table field of the Backend Services, the table of the server network is selected. TR7 receives the client from one table and connects to the Backend Service from the other table
The Backend Service can be reached only from a segment in another table	That table is selected in the Route Table field of the Backend Service
The networks of different customers or environments are kept separate from each other	The interfaces of each are moved to a separate table; the Backend Services and Network vServices are defined with the related table
The Network vService will be published in another segment	That table is selected in the Route Table field of the Network vService; then the Frontend IP, SNAT IP and Backend Services are selected again

Common Misconceptions

• "A Route Table is just a routing list." In TR7, a Route Table is a separate network domain with its own interfaces and IPs; tables do not see each other's traffic.
• "If the Backend Service's table is wrong, TR7 reaches it another way." TR7 connects to the Backend Service only from the selected table; if the server cannot be reached from that table, the health check fails.
• "Changing the Network vService's table preserves the other settings." When the table changes, the Frontend IP, SNAT IP and Backend Service selections are cleared and are made again.

How it is done in the documentation

• Route Tables · What Is Route Tables?
• Route Tables · Usage Location
• Backend Services · Route Table
• Network vService · Route Table

Related questions

• What do I need to do on the network side first to open a vService on an IP in a different subnet / VLAN?
• Can my backends be on different networks / in different route tables?
• What does "Default" in the SNAT field mean; can I choose a specific SNAT IP?
• Do I need to change my network topology to add TR7 (one-arm / two-arm / inline)?