This gives the name of the specific tunnel that this associated tunnel is protecting -- i.e., the primary path this entry stands ready to take over for, or vice versa. An admin uses this pointer to quickly locate the paired tunnel when investigating a protection-related event, without having to search the whole tunnel table for the matching partner. For example, seeing a partner name of vip-customer-primary-lsp on a backup tunnel entry immediately tells the admin which primary service this specific backup exists to cover.