OSI Stands for open system interconnection model.  This is reference or virtual model, you cannot see it , touch it ,but its exists conceptually just like electron, protons etc. OSI model is invented by ISO(International standard organization). ISO is non profit organization that defines several  standards. It is just like other standard e.g ISI mark,

Site to Site IPsec VPN

Topology Summary: To implement Flex VPN or IPSEC VPN the topology shown above. The motive is to make the reachability between LAN to LAN network i.e from to & vice versa. Currently we have configure simple connectivity in which R1 and R2 is reachable to each other via internet cloud. The basic requirement

Gre Tunnel

Topology Objectives Create Gre tunnel between Router A and Router c. We are creating tunnel to internal communication between two LAN segments without, advertising LAN IP in internet domain. Steps: Your end to end network should be reachable i.e the interface/node from where you are creating tunnel should reachable to destination interface/node. Here Router A

MPLS lsp path broken

Topology:   Objective: To test the broken LSP failover using LDP protocol. All router in the topology are running under OSPF area 0.LDP has been enabled between them. Currently LDP synced and LDP neighbor ship has been established between all routers. As depicted in topology Router R2 have two path to reach to Router R9