Route Distinguisher and Route Target
Route Distinguisher
A Route Distinguisher is a unique prefix added to a customer's destination address to distinguish advertisements that might otherwise look the same. For example, overlapping VRF subnets can be distinguished by unique route distinguishers.
An RD is a 64-bit integer and is split into three parts:
- Type (always 2 bytes).
- Administrator subfield.
- Value or service-provider subfield.
Currently, three format types are defined.
| 2 bytes | 2 bytes | 4 bytes | |
|---|---|---|---|
| Type 0 | ASN | 4-byte value | |
| Type 1 | 4-byte IP | 2-byte value | |
| Type 2 | 4-byte ASN | 2-byte value |
Route Targets
A Route Target is a BGP extended community that controls the import and export of routing information between routing instances.