Patent ID: 8289961

Claim:
A method performed on a network element implementing an Open Shortest Path First (OSPF) protocol to handle Link State Identifier (LSID) collisions to prevent different link state advertisements (LSAs) associated with different routes from sharing the same LSID, wherein each LSA is identified by an assigned LSID, the method comprising the steps of: during an LSID assignment process for a first route, performing the following steps: generating a tentative LSID for the first route; determining that the value of the tentative LSID is already assigned to an LSA for a second route, and further determining that one of the first and second routes is a host route, wherein the host route is a route that has a host route mask, and wherein the first and second routes are different; responsive to a determination that the host route is the first route, performing the following step: suppressing the first route to prevent an LSID collision between the first and second routes, wherein the step of suppressing includes the step of not originating an LSA for the first route; responsive to a determination that the host route is the second route, performing the following steps: suppressing the second route to prevent an LSID collision between the first and second routes, wherein the step of suppressing includes the step of purging the LSA for the second route; and originating an LSA for the first route with the value of the tentative LSID; wherein network reachability for a range subsuming the host route is provided through the one of the first and second routes that is not suppressed; and whereby LSAs for different routes, including host routes, are prevented from sharing the same LSID while each of the routes is reachable even in the presence of suppressed host routes.