F5 Route Domains

--> Route domain concept is similar to VRF in Cisco, which is used to divide one routing table into multiple routing tables.

--> With the help of Route domains we can provide hosting service for multiple customers by separating each type of application traffic within a defined address space on the network.

--> With route domains, you can also use duplicate IP addresses on the network, because each of the duplicate addresses resides in a separate route domain and is separated from the network through a separate VLAN.

-->  For example, if you are processing traffic for two different customers, you can create two separate route domains. The same node address (such as 10.0.10.1) can reside in each route domain, in the same pool or in different pools, and you can assign a different monitor to each of the two corresponding pool members.

--> Route domains are identified by using Domain ID in F5 whereas in cisco numbers are used to identify VRF.

--> A route domain ID is a unique numerical identifier for a route-domain. You can assign objects to IP addresses (such as self IP addresses, virtual addresses, pool members, and gateway addresses) to a route domain by appending the %ID to the IP address.

--> The format required for creating a route domain ID in an object’s IP address is A.B.C.D%ID, where ID is the number of the relevant route domain.

--> For example, both the local traffic node object 10.10.10.30%2 and the pool member 10.10.10.30%2:80 pertain to route domain 2.

--> By default Route Domain ID "0" is used, If you do not manually create any route domains, all routes in the system assigned to route domain 0.

--> Any BIG-IP addresses that do not include the route domain ID notation are automatically associated with the default route domain.

--> A route domain ID must be unique on the BIG-IP system; that is, no two route domains on the F5 LTM can have the same ID.

--> Each route domain can have a Parent route domain identified using Pparent ID. The parent ID identifies another route domain on the F5 LTM that the system can search to find a route if it is not available in the route domain (child).

--> Forwarding of traffic between route domains is by default enabled between route domains in a parent-child relationship only.  We can disable this behavior by enabling strict isolation feature.

--> It is recommended to configure each route domain in the separate partition in F5 LTM.

Reference: F5