klepysik (klepysik) wrote,

Difference between Graseful and signaled restart in OSPF

Difference between Graseful and signaled restart in OSPF
Делаю свою презентацию и никак не могу найти "понятные" отличия между graceful and signaled restarts.
От rfc уже голова болит :(
Может кто может помочь?
На данный момент выяснила что-

OSPF Graceful restart :
Graceful restart using LSA checking indicates whether a changed LSA
will result in the termination of graceful restart by a helping router.

OSPF signaled restart :
1. This draft extends the OSPF Hello packet format to include TLVs, which can then be used to include
additional signaling of various types, such as graceful restart capability and a graceful restart.
2. This draft describes a mechanism through which two OSPF routers can resynchronize their link-state
databases at any point .

Короче graceful смотрит есть ли измененные LSA чтобы узнать если падают раутеры, то врубает graceful. А signaled использует hello packets и если не получает - врубает signaled.

Кто- то может что то добавить?

p.s. helping router для graceful restart это :
When a neighbor router that is on the same network segment as the restarting router receives a grace-LSA from the restarting router, the neighbor enters helper mode as long as the following criteria are met:
•The neighbor must have a full adjacency with the restarting router over the associated network segment.
•There have been no changes to the link-state database since the restarting router began restarting.
•The grace period has not yet expired.
•Local policy allows the neighbor router to act as a helper router.
•The neighbor router must not be in its own graceful restart process.
•Helper mode for this router has not been disabled by the network administrator.

Helper Mode Exit
The helper router stops performing helper mode for its neighbor when one of the following events occur:
•The grace-LSA that was originated by the restarting router is flushed, to signify that the restarting router has exited the graceful restart process successfully.
•The grace period of the grace-LSA expires.
•A change in link-state database contents indicates a network topology change, forcing the termination of the graceful restart process.
RFC 3623

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