> # Link Initialization WWN Usage

> Exchange Link Protocol (ELP) and Exchange Fabric Protocol (EFP) use WWNs during link initialization. The usage details differ based on the Cisco NX-OS software release.

> Both ELPs and EFPs use the VSAN WWN by default during link initialization. However, the ELP usage changes based on the peer switch’s usage:

> - If the peer switch ELP uses the switch WWN, then the local switch also uses the switch WWN.
> - If the peer switch ELP uses the VSAN WWN, then the local switch also uses the VSAN WWN.

> Note As of Cisco SAN-OS Release 2.0(2b), the ELP is enhanced to be compliant with FC-SW-3.

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