Mohamad Chaitou

Multi-point to multi-point traffic engineering

The MPLS-TE technology, relying on the signaling protocol RSVP-TE, ensures traffic engineering (TE) features for point-to-point (P2P) and point-to-multipoint (P2MP) applications with strong bandwidth and availability needs. This paper defines the concept of multi-point to multi-point (MP2MP) TE-LSP that connects a group of nodes called leaves, acting as senders and/or receivers, with potentially distinct bandwidth needs. This helps in replacing the P2P or P2MP TE-LSPs that connect a group of nodes by one MP2MP TE-LSP which leads to reducing the number of TE-LSPs in MPLS-TE networks and hence improving its scalability. An MP2MP TE-LSP can be used also to support value added multi-point to multi-point applications such as visio-conferencing. The setup of an MP2MP TE-LSP relies upon minor extensions to RSVP-TE. An MP2MP TE-LSP is initiated by a root router and the signaling messages from the root to the leaves include the bandwidth requested by each leaf. The bandwidth reserved on a link in each direction is deduced from the bandwidth requested by upstream and downstream leaves. This mechanism inherits all good properties of MPLS-TE with only a few extensions and it permits to set up P2P and P2MP TE-LSPs since such TE-LSPs are special cases of MP2MP TE-LSPs.

Fast-reroute extensions for multi-point to multi-point MPLS tunnels

This paper proposes fast reroute extensions to RSVP-TE in order to support the protection of multipoint to multipoint (MP2MP) MPLS TE-tunnels. To protect an element (link or node) of a primary MP2MP TE-tunnel, we propose to use an MP2MP bypass TE-tunnel connecting a set of nodes around the protected element. During failure the primary MP2MP TE-tunnel is encapsulated into the MP2MP bypass TE-tunnel which calls for defining a new type of MPLS hierarchy, the multipoint to multipoint hierarchy. The node of the primary MP2MP TE-tunnel upstream to the protected element, called the upstream protecting node (UPN), selects the MP2MP bypass TE-tunnel to be used for the protection. By extending the point to multipoint MPLS hierarchy, which relies on the upstream label assignment, we discuss several extensions scenarios depending on the number of leaves of a bypass TE-tunnel and on the number of UPNs per bypass tunnel. The scalability/bandwidth-consumption tradeoff between these schemes is analyzed by means of simulations. The proposed method can be efficiently used for the protection of point-to-point and point-to-multipoint TE-tunnels as well, as such tunnels are actually particular cases of MP2MP TE-tunnels.

On Optimizing Leaf Initiated Point to Multi Point Trees in MPLS

Resource ReSerVation Protocol-Traffic Engineering (RSVP-TE), and Label Distribution Protocol (LDP) may be used to set up Point to Multi Point (P2MP) trees in MPLS. RSVP-TE performs better in optimizing network resources, while LDP is simpler but has no guarantee on resource optimization. This paper presents a comparative study between RSVP-TE and LDP in regards of resource optimization and the resulting impact on the amount of memory consumed. It shows that the amount of memory needed in the case of RSVP-TE grows linearly as the size of the tree increases. In contrast, an approximate constant behavior is observed in the case of LDP, yielding an important scalability property. The paper then proposes two extension to LDP aiming to achieve better resource optimization. In both extension, a new leaf is provided a partial tree knowledge, by involving either all the nodes of the tree or only its leaves. The leaf joins the tree by connecting to the closest node among the known ones. Valuable comparisons with RSVP-TE are performed, and they represent an important background to decide when and how to use each protocol.

Fast-reroute procedures for multi-point to multi-point MPLS tunnels

This paper proposes fast reroute extensions to RSVP-TE in order to support the protection of multipoint to multipoint (MP2MP) MPLS TE-tunnels. To protect an element (link or node) of a primary MP2MP TE-tunnel, we propose to use an MP2MP bypass TE-tunnel connecting a set of nodes around the protected element. During failure the primary MP2MP TE-tunnel is encapsulated into the MP2MP bypass TE-tunnel which calls for defining a new type of MPLS hierarchy, the multipoint to multipoint hierarchy. The node of the primary MP2MP TE-tunnel upstream to the protected element, called the upstream protecting node (UPN), selects the MP2MP bypass TE-tunnel to be used for the protection. By extending the point to multipoint MPLS hierarchy, which relies on the upstream label assignment, we discuss several extensions scenarios depending on the number of leaves of a bypass TE-tunnel and on the number of UPNs per bypass tunnel. The scalability/bandwidth-consumption tradeoff between these schemes is analyzed by means of simulations. The proposed method can be efficiently used for the protection of point-to-point and point-to-multipoint TE-tunnels as well, as such tunnels are actually particular cases of MP2MP TE-tunnels.