In an RSVP-based MPLS network, which ERO type specifies the exact order of routers through which an LSP must travel, without consulting the IGP?
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A. B. C. D.D
When a strict hop is configured, it identifies an exact path through which the LSP must be routed. Strict-hop EROs (Explicit Route Objects) specify the exact order of the routers through which the RSVP messages are sent.
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A: When a loose hop is configured, it identifies one or more transit LSRs through which the LSP must be routed.
The network IGP determines the exact route from the inbound router to the first loose hop, or from one loose hop to the next.
The loose hop specifies only that a particular LSR be included in the LSP.
https://forums.juniper.net/t5/Routing/loose-and-strict-option/td-p/164626In an RSVP-based MPLS network, the Explicit Route Object (ERO) is used to specify the exact path that an LSP (Label Switched Path) must take through the network. The ERO can contain different types of hops, including strict hops, loose hops, next hops, and labeled hops.
Among these, the strict hop is the ERO type that specifies the exact order of routers through which an LSP must travel, without consulting the IGP (Interior Gateway Protocol) for path selection. When a strict hop is used, the LSP must follow the exact path specified in the ERO, and any other paths that may be available in the network are not considered.
In contrast, a loose hop allows the LSP to take different paths between specified routers, as long as the destination is reached. The next hop is used to specify the IP address of the next router that the LSP must pass through. This is useful when the path to the destination is not known in advance, and the LSP must consult the IGP to find the best path.
Finally, a labeled hop is used to specify a specific label that must be pushed onto the packet at a particular hop in the path. This is typically used in situations where the label distribution protocol is used to distribute labels dynamically, and the ERO must specify a particular label for a particular hop.
In summary, the strict hop ERO type is used in RSVP-based MPLS networks to specify the exact order of routers through which an LSP must travel, without consulting the IGP. This provides a way to guarantee that the LSP follows a specific path through the network.