Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

The Effect of Delay Mismatch in MPLS Networks Using 1+1 Protection



David W. Griffith, Sanghun Lee, L Krivulina


High-capacity optical-fiber backbone networks protect information flows belonging to their premium customers by routing two copies of the customer's data over disjoint paths. This scheme, known as 1+1 protection, ensures that the customer will experience no service interruptions even if a fiber cut occurs somewhere in the network. A protection scheme based on this concept was proposed for Multi- Protocol Label Switched (MPLS) packet flows at the Spring, 2002, meeting of the Internet Engineering Task Force (IETF) by a team from Lucent. The Lucent proposal will require the MPLS routers located at the ingress and egress edges of the MPLS network to protect certain data flows by creating two disjoint label switched paths (LSPs). Packets using the 1+1 protection service are duplicated at the ingress router, assigned an ID number, and sent to the egress router over the two LSPs. The egress router retrieves the least-delayed copy of each packet and forwards it to the destination, discarding the more-delayed copy. A sliding window allows the egress router to function even when packet losses occur. This scheme allows data to flow even if a link failure occurs on one of the LSPs, but a sufficiently large difference in the propagation delays associated with the two protection LSPs can cause performance degradations that may reduce the protected flow's quality of service (QoS) below what is acceptable to the customer. In this paper we examine the impact of delay mismatch on the probability of packet loss and on packet jitter, and we show that both of these metrics are adversely affected by large LSP delay differences.
Proceedings Title
Proceedings of the 2002 International Conference on Parallel Processing
Conference Location
August 18-21,
Conference Title
(Vancouver, Canada)


MPLS 1+1 protection, QoS


Griffith, D. , Lee, S. and Krivulina, L. (2003), The Effect of Delay Mismatch in MPLS Networks Using 1+1 Protection, Proceedings of the 2002 International Conference on Parallel Processing, August 18-21, , [online], (Accessed June 14, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created May 1, 2003, Updated February 19, 2017