Inter-Domain Routing with Multi-Dimensional QoS Requirements

Abstract

External border gateway protocol (eBGP) is the ubiquitous protocol used today for advertisement of reachability information and for route selection among administrative domains (autonomous systems or ASs) in the Internet. However, many emerging needs in commercial and military networking have exposed limitations of the current eBGP. In particular, these IP networks of the future carries a very diverse mix of applications, with very diverse quality of service (QoS) requirements (in the broad sense of the phrase). Some of these networks also have a very diverse set of component networks (wireless and wireline, fixed and mobile with different degrees of mobility, long lived and short term ad-hoc) and some of the component networks may be very dynamic in their service capabilities. These scenarios call for enhancing eBGP to allow for multi-topology and QoS-aware routing, using several QoS metrics in decision making. In such an enhanced BGP, more than one route (or path vector) may be propagated in BGP_UPATE messages, helping optimize with respect to different QoS metrics as needed by different traffic types. In this paper, we discuss such an enhancement of eBGP. We develop details of advertisements, route thinning, and route selection needed to make the eBGP multi-topology and QoS-aware in the sense described above. We take the eBGP and internal BGP (iBGP) advertisement and route selection process and identify any modifications needed at each stage. We also discuss interactions between eBGP and iBGP and between BGP and the interior (intra-domain) gateway protocol (IGP) needed to make the approach work end-to-end. We also discuss alternative ways to ensure that packets follow the selected end-to-end routes (both within and between domains). In particular, the potential uses of MPLS, source routing, tunneling, and DiffServ/ToS bits for this purpose are discussed in the paper