# BFD Version Support

The JunosE Software supports both BFD Version 0 and BFD Version 1. When establishing a BFD neighbor session, the E Series router attempts to establish version 0 or version 1 sessions based on the capability of the BFD neighbor. Table 7 indicates how the routers establish sessions based on BFD version support:

Table 7: Determining BFD Versions

|  | E Series Routers Running JunosE 7.2.x (and later) | E Series Routers Running Software Versions Earlier than JunosE 7.2.x
| BFD Version Support | Version 0 and Version 1 | Version 0 Only
E Series Routers Running JunosE 7.2.x (and later) and Other Routers | Version 0 and Version 1 | Result = Version 1 | Result = Version 0
E Series Routers Running Software Versions Earlier than JunosE 7.2.x and Other Routers | Version 0 Only | Result = Version 0 | Result = Version 0
Other Routers | Version 1 Only | Result = Version 1 | No session (version mismatch)

| Note: You cannot configure the JunosE Software to send BFD Version 0 or BFD Version 1 packets. The JunosE Software determines the BFD version through auto-negotiation.