Patent ID: 7451241
Filing Date: 2008-11-11
Classification: H04L

Abstract:
1. A method for protecting a label switched path (LSP) between two label switch routers (LSRs) in a ring network that utilizes multiprotocol label switching (MPLS) to communicate packets of information, wherein each LSR in said ring network is connected to a right side neighbor LSR and a left side neighbor LSR by respective links, said method comprising: identifying a working LSP between first and second neighbor LSRs in said ring network, said working LSP having a first direction around said ring network; establishing a protection LSP between said first and second neighbor LSRs for communicating packets between said first and second neighbor LSRs in the event of a failure of the link that is utilized by said working LSP, said protection LSP utilizing said ring network and having an opposite direction to said first direction; switching packets from said working LSP to said protection LSP in response to a failure of said link that is utilized by said working LSP, wherein switching packets from said working LSP to said protection LSP includes adjusting time-to-live (TTL) values of said packets to account for the number of LSRs that are along said protection LSP; switching packets back to said working LSP from said protection LSP after said packets have traversed said protection LSP; and using TTL values from packets that have traversed said protection LSP to generate TTL values for said packets that are switched back to said working LSP from said protection LSP.