A Network Layer Approach to Enable TCP over Multiple Interfaces

Abstract

The mobile Internet is set to become ubiquitous with the deployment of various wireless technologies. When heterogeneous wireless networks overlap in coverage, a mobile terminal can potentially use multiple wireless interfaces simultaneously. In this paper, we motivate the advantages of simultaneous use of multiple interfaces and present a network layer architecture that supports diverse multiaccess services. Our main focus is on one such service provided by the architecture: Bandwidth Aggregation (BAG), specifically for TCP applications.While aggregating bandwidth across multiple interfaces can improve raw throughput, it introduces challenges in the form of packet reordering for TCP applications. When packets are reordered, TCP misinterprets the duplicate ACKS received as indicative of packet loss and invokes congestion control. This can significantly lower TCP throughput and counter any gains that can be had through bandwidth aggregation. To improve overall performance of TCP, we take a two-pronged approach: (1) We propose a scheduling algorithm that partitions traffic onto the different paths (corresponding to each interface) such that reordering is minimized. The algorithm estimates available bandwidth and thereby minimizes reordering by sending packet pairs on the path that introduces the least amount of delay. (2) A buffer management policy is introduced at the client to hide any residual reordering from TCP. We show through simulations that our network-layer approach can achieve good bandwidth aggregation under a variety of network conditions.

BATCP: Bandwidth-Aggregation Transmission Control Protocol

“…Chebrolu et al propose in [8][9][10][11] a network layer solution based on Mobile IP. The remote host has multiple care-of addresses, and the network proxy uses them to redirect incoming traffic from these addresses to the multi-homed node's local address.…”

“…Network layer solutions found in [8][9][10][11][12][13][14][15][16][17][18][19][20][21] have to deal with a common constraint: the requirement of a modified proxy server based on Mobile IP. Experimental results show that Mobile IP solely introduces a significant amount of delay in the communication, and thus minimizes performance [22][23][24].…”

A case for enhancing dual radio repeater performance through striping, aggregation, and channel sharing

“…In contrast, Multifacet is a custom dual interface repeater which does no need application of system modifications at end host modifications. Authors in [25,33] study end-to-end flow striping techniques, however, our flow striping is not end-to-end but restricted to a single hop.…”

Multipath aggregation of heterogeneous access networks

“…Chebrolu et al [35,36] present a network-layer architecture for bandwidth aggregation with an infrastructure proxy as its core element. Aware of the IP addresses on multihomed clients, the proxy estimates packet delivery times to intelligently stripe packets with the goal of minimizing packet reordering at the receiver.…”

“…In order to prevent firewalls in access networks to filter out IP packets that appear as spoofed, we encapsulate all traffic in L2TP [162] tunnels. As opposed to the IP-in-IP tunneling solutions proposed in [35] and [132], L2TP is applicable to our practical WLAN/HSPA scenario, because it uses NAT-punching to reach local interface addresses.…”