Implementation and performance evaluation of diffserv enabled MPLS testbed for Linux using past information of queue

The advent of Multi Protocol Label Switching (MPLS) has reach beyond the original idea behind the development of MPLS. The original idea behind MPLS was to facilitate fast packet switching using 20 bit MPLS Label header. Presently Traffic Engineering has drawn considerable major interest of the researcher. In this paper we describe an algorithm to use multiple Link Switching Path (LSP) for MPLS which is implemented in GNU Linux under link overload condition. This work has been done using MPLS-Linux GNU project. This algorithm collects the statistics of Hierarchical Token Bucket (HTB) queueing discipline inside Linux Advanced Routing and Traffic Control (LARTC) subsystem. HTB allows the sharing of unused allocated bandwidth among the leaf classes under the same parent class of queue defined by the administrator of Network. Our algorithm will split the low priority traffic over multiple LSPs during overload and fallback to single LSP in the absence of overload. A Kernel module has been developed to consistently check the bandwidth usage and HTB buffer health to feed the information to our algorithm and communiacting another user space program to trigger the traffic split. The communication between Kernel and user space program is done by Netlink socket. As a process of modifying the exisitng Kernel code we have also verified the interoperability of Differentiated Services Code Point (DSCP) in IP and Experimental bits (EXP) in MPLS. An experimental testbed has been setup using Linux and performance metrics such as delay, packet loss has been analyzed for MPLS with and without traffic splitting on overload condition on this testbed.