When the last link expires, the entire instance expires.
| TwoHopNeighbor (EventLoop& ev,
		   Neighborhood* parent,
		   const OlsrTypes::TwoHopNodeID id,
		   const IPv4& main_addr,
		   const OlsrTypes::TwoHopLinkID tlid) | TwoHopNeighbor | 
| inline OlsrTypes::TwoHopNodeID  id () | id | 
[const]
| inline IPv4  main_addr () | main_addr | 
[const]
| void  add_twohop_link (const OlsrTypes::TwoHopLinkID tlid) | add_twohop_link | 
Associate this N2 with an N1, using an instance of the association class TwoHopLink.
Parameters:
| tlid | the ID of a two-hop link. | 
| bool  delete_twohop_link (const OlsrTypes::TwoHopLinkID tlid) | delete_twohop_link | 
Delete the given N1 from the set of Neighbors which may be used to reach this N2.
Parameters:
| tlid | the ID of a two-hop link. | 
Returns: true if the last link to the TwoHopNeighbor was removed.
| size_t  delete_all_twohop_links () | delete_all_twohop_links | 
| inline const set<OlsrTypes::TwoHopLinkID>&  twohop_links () | twohop_links | 
[const]
| void  add_covering_mpr (const OlsrTypes::NeighborID nid) | add_covering_mpr | 
Add the given neighbor as an MPR which covers this node.
Parameters:
| nid | the N to count as one of this N2's covering nodes. | 
| void  withdraw_covering_mpr (const OlsrTypes::NeighborID nid) | withdraw_covering_mpr | 
Withdraw the given neighbor as an MPR which covers this node.
Parameters:
| nid | the N to count as one of this N2's covering nodes. | 
| void  reset_covering_mprs () | reset_covering_mprs | 
Reset the MPR coverage state for this N2 node.
| inline uint32_t  coverage () | coverage | 
[const]
Returns: The number of MPRs which cover this node.
| inline bool  is_covered () | is_covered | 
[const]
Returns: true if this N2 is covered by at least N1.
| inline uint32_t  reachability () | reachability | 
[const]
Returns: The number of MPR candidates which cover this node. This is not computed here but by Neighborhood, the parent. Note: This is NOT the same as a neighbor's reachability.
| inline void  set_reachability (uint32_t value) | set_reachability | 
| inline bool  is_reachable () | is_reachable | 
[const]
Returns: true if this N2 is reachable.
| bool  is_strict () | is_strict | 
[const]
An N2 is strict if it appears only in the two-hop neighborhood, and not in the one-hop neighborhood.
Returns: true if this N2 is strict.
| void  set_is_strict (bool is_strict) | set_is_strict | 
Set if this N2 is a strict two-hop neighbor.
Parameters:
| is_strict | true if this N2 does NOT also appear as an N1. | 
| const set<OlsrTypes::TwoHopLinkID>&  twohop_links () | twohop_links | 
Returns: the set of two-hop links pointing to this N2 node.