windows-server-2003/net/rras/ip/igmp

#if (0)



//------------------------------------------------------------------------------

// Abbreviations:

//------------------------------------------------------------------------------



abbr:    struct type          description



pite:   PIF_TABLE_ENTRY:      pointer to interface table entry

pge:    PGROUP_TABLE_ENTRY:   pointer to group entry in group table.

GI_entry:                     the group entry for an interface.

pgie:   PGI_ENTRY:            pointer to group entry for an interface. It 

                              hangs from both pite and pge lists.

ppge:   PPROXY_GROUP_ENTRY:   pointer to group joined on proxy interface.

                              Hangs from pite & also listed in proxy hash table

ptg:                          pointer to timer global.                              

DCS:                          Dynamic critical section lock

DRW:                          Dynamic read-write lock

IF:                           Interface

groups-if list                list of all gi entries accessed through the 

                              ordered group list.

if-groups list                list of all gi entries accessed through the

                              ordered interface list.





    

//------------------------------------------------------------------------------

// Optimizations that can be done:

//------------------------------------------------------------------------------



1. Dynamically change the size of the interface, group, & proxy hash tables

2. Release InterfaceList locks early in AddInterface, DeleteInterface, etc.

   (in that case you have to set a flag saying being initialized, so that that

   interface is not enumerated)









//------------------------------------------------------------------------------

// Order of Locking:

//------------------------------------------------------------------------------



sockets-list    CSLock      protects the list of socket-event binding entries.

                            (many sockets, ie igmprtr interfaces are bound to 

                            the same wait-event entry).

                            Take write lock when the interface is being created,

                            deleted, activated or protocol change.

                            Take read lock when the input packet is being 

                            processed.



IF-list         CSLock      protects the ordered interface list 

                                g_pIfTable->IFLists_CS

                                

IF-bucket       DRWLock     protects the interface entry.

                            actually one lock for each interface hash bucket.

                            A write lock is required when an interface is 

                            created, deleted, activated or its config is changed.

                                g_pIfTable->[IFbucket].DRWLock

                                

Group-bucket    DCSLock     protects the group entry.

                            actually one lock for each group hash bucket.

                            Need this lock whenever accessing a group through

                            group hash table, or when adding/removing a GIentry

                            from a group list.

                                g_pGroupTable->[groupBucket].DCSLock



IF-groups-list  DCSLock     protects the list of gi_entries hanging from that IF.

                            actually one lock for each interface hash bucket.

                            can access/change a GI entry without this lock. 

                            however, this lock is required when a gi entry is 

                            created or delete.

                                g_pIfTable->[IFbucket].DCSLock

                                

Group-list      CSLock      protects the list of ordered groups.



Global lock     CSLock      protects

                                g_CS

Note: a problem arises when enumerating the groups-if list. I first take the

group-list lock, find the next group entry, release the group-list lock,

and then lock the group-bucket and access its fields.









//------------------------------------------------------------------------------

// Configuration

//------------------------------------------------------------------------------



1. Proxy cannot be configured on a RasServer interface, ie interface of type

   LOCAL_WORKSTATION_DIAL.

   

2. When IgmpRouter is configured on a RasServer interface(LOCAL_WORKSTATION_DIAL)

   no igmp Group Specific packets are sent in response to leave packets. This

   is based on the fact that there is only one ras-client on the other end.

   

3. When igmp router is configured on an interface, it sends StartupQueryCount

   General queries on that inteface spaced at StartupQueryInterval. The next

   General query timer is set to random value in [0,GenQueryInterval]. This is 

   so that when 'N' interfaces are configured with igmp router at startup, 

   all of them do not send General Queries at the same time (my own feeble 

   attempt to avoid synchronization of General Queries on different interfaces 

   of a router).







#endif // if (0)