US 7,388,828 B2 | ||
Method for rerouting MPLS traffic in ring networks | ||
Shaul Nakash, Kfar Sava (Israel) | ||
Assigned to ECI Telecom Ltd., Petach Tikva (Israel) | ||
Filed on Oct. 29, 2004, as Appl. No. 10/975,921. | ||
Claims priority of application No. 158656 (IL), filed on Oct. 29, 2003. | ||
Prior Publication US 2005/0094554 A1, May 05, 2005 | ||
Int. Cl. H04J 1/16 (2006.01); H04L 12/28 (2006.01) |
U.S. Cl. 370—218 [370/222; 370/392] | 11 Claims |
1. A method for protecting packets of MPLS traffic in ring networks comprising a ring having a plurality of nodes, in case
when a section extending between at least two nodes of said ring becomes faulty, wherein the MPLS traffic comprises two or
more Label Switched Paths (LSPs) entitled to protection, and wherein each of said packets carries an original label corresponding
to a specific LSP, the method comprising:
at a first edge node bordering the faulty section, redirecting the MPLS traffic in the opposite direction along the ring,
via a shared protection path;
when being redirected to the protection path at the first edge node, providing each of the redirected packets with an additional,
outer label to its label stack, said additional label indicating the fact that the packet is carried along the protection
path;
recognizing the packets belonging to the redirected MPLS traffic by detecting, at the protection path nodes presence of said
additional label;
for each packet arriving at a particular node along said protection path and recognized as belonging to the redirected MPLS
traffic by detecting said additional label, determining whether the particular node is the packet's egress point from the
ring,
said determining being performed depending on arrangement of the protection path:
in case said protection path is arranged as a chain of point-to point LSPs (a point-to-point, ptp, protection path) or multipoint-to-multipoint
(mptmp) protection path, the determining comprises mandatory checking the original, inner label of the packet at the particular
node,
in case said protection path is arranged as a multipoint-to-point (mptp) protection path, the determining comprises checking
the original, inner label of the packet if said particular node is a termination point of said mptmp protection path,
the method then comprises
allowing egress of said packet of the redirected MPLS traffic from the ring at said particular node, if said particular node
is either the termination point of the mptp path or the packet's egress node from the ptp or mptmp protection path,
forwarding said packet of the redirect MPLS traffic to a next node along the ring, said particular node is neither the termination
point of the mptp protection path nor the packet's egress node from the ptp or mptmp protection path.
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