Ingress router
Encyclopedia
An "ingress router" is a Label Switch Router
that is a starting point (source) for a given Label Switched Path
(LSP). An ingress router may be an egress router
or an intermediate router for any other LSP(s). Hence the role of ingress and egress routers is LSP specific. Usually, the MPLS
label is attached with an IP packet at the ingress router and removed at the egress router, whereas label swapping is performed on the intermediate routers. However, in special cases (such as LSP Hierarchy in RFC 4206, LSP Stitching http://tools.ietf.org/html/draft-ietf-ccamp-lsp-stitching-06 and MPLS local protection
) the ingress router could be pushing label in label stack of an already existing MPLS packet (instead of an IP packet). Note that, although the ingress router is the starting point of an LSP, it may or may not be the source of the under-lying IP packets.
Label Switch Router
A label switch router , is a type of a router located in the middle of a Multiprotocol Label Switching network...
that is a starting point (source) for a given Label Switched Path
Label Switched Path
In MPLS networking, a Label Switched Path is a path through an MPLS network, set up by a signaling protocol such as LDP, RSVP-TE, BGP or CR-LDP. The path is set up based on criteria in the forwarding equivalence class ....
(LSP). An ingress router may be an egress router
Egress router
An egress router is a Label Switch Router that is an end point for a given Label Switched Path . An egress router may be an ingress router or an intermediate router for any other LSP. Hence the role of egress and ingress routers is LSP specific...
or an intermediate router for any other LSP(s). Hence the role of ingress and egress routers is LSP specific. Usually, the MPLS
Multiprotocol Label Switching
Multiprotocol Label Switching is a mechanism in high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels identify virtual links between...
label is attached with an IP packet at the ingress router and removed at the egress router, whereas label swapping is performed on the intermediate routers. However, in special cases (such as LSP Hierarchy in RFC 4206, LSP Stitching http://tools.ietf.org/html/draft-ietf-ccamp-lsp-stitching-06 and MPLS local protection
MPLS local protection
MPLS Fast Reroute is a local restoration network resiliency mechanism. It is actually a feature of RSVP Traffic Engineering . In MPLS local protection each LSP passing through a facility is protected by a backup path which originates at the node immediately upstream to that facility...
) the ingress router could be pushing label in label stack of an already existing MPLS packet (instead of an IP packet). Note that, although the ingress router is the starting point of an LSP, it may or may not be the source of the under-lying IP packets.