Multiprotocol Label Switching ( MPLS) Segment Routing (SR), SR-MPLS in short, is anrnMPLS data plane-based source routing paradigm in which a sender of a packet is allowed tornpartially or completely specify the route the packet takes through the network by imposingrnstacked MPLS labels to the packet. SR-MPLS could be leveraged to realize a unified sourcernrouting mechanism across MPLS, IPv4 and IPv6 data planes by using an MPLS label stack asrnunified source routing instruction set while preserving backward compatibility with traditionalrnMPLS networks. rnThe Segment Routing is a promising Traffic Engineering (TE) model that provides end-to-endrncommunications. SR can observably improve the network utilization and control the routingrnpath flexibly by encoding route information into a list of segments, i.e., the Segment List (SL).rnThe key feature of SR is that it adopts the source routing paradigm, which implies the routingrnpath followed by a packet is determined and written to the packet header by the first switch ofrnSR networks (called Ingress SR switch). rnThe motivation of this thesis is to investigate and analyze the impact of implementing SRMPLSrnonrnQualityrnofrnServicern(QoS).rnThernimpactrnonrnQoSrnparametersrnisrnanalyzedrnbyrnusingrntwornrnscenarios;rnTraditionalrnUnifiedrnMPLSrnintegratingrnfourrndomainsrnintornsinglernMPLSrndomainrnandrnrnSegmentrnRoutingrnoverrnUnifiedrnMPLSrnintegratingrnfourrndomainsrnintornarnsinglernMPLSrndomain. rnrnSimulationrntoolsrnsuchrnasrnEVE-NG,rnOstinato,rnCiscornrnIPSLA technology are used to comparernperformances of the two scenarios. The analysis results show that in SR-MPLS throughput isrnimproved on average by 32%, latency is improved by 24%, packet loss is improved by 20.4%rnand jitter is improved by 12.6% compared to Label Distribution Protocol (LDP) based UnifiedrnMPLS. From the results, one can understand that any service provider can benefit fromrndeploying Unified SR-MPLS. Segment Routing is a new routing paradigm that provide a betterrnend-to-end QoS guarantee, making traditional MPLS network more efficient and scalable.