Taqdir, My understanding is that Router Alert Label (value 1) is analogous to router alert option. IP header Option: For instance when record route or strict / loose source routing option is set in IP header, every router in the hop needs to look at the packet in detail (& not only forward it using the destination IP address). For this reason packets with Options marked are generally switched by software. Same is the case with Router Alert MPLS label & it provides the exact same function as Option field in IP Header. This label can be anywhere in the stack, however, not at the bottom of the stack. When a router receives a packet with label 1 at the top it punts the packet to CPU. CPU then forwards tha packet based on the next label. (Since the packet is being processed by CPU the path this packet takes to destination can be recorded). If a router has to forward the MPLS packet, it replaces the MPLS label of 1 at the top of the stack so that the next router in the path can perform similar function. (The only condition is that MPLS label 1 cannot be the bottom label in the stack). Hope this helps!!
________________________________ From: Taqdir Singh <[email protected]> To: "[email protected]" <[email protected]> Sent: Wednesday, 17 April 2013 11:17 AM Subject: [OSL | CCIE_RS] MPLS Router alert label 1 hi team.. what is router alert label.. in which scenario is it relly used.. not able to get any good details on it.. _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
