Peer-to-Peer Traffic in Operator Networks

Abstract

This paper examines the issues encountered by network operators when content providers utilize peer-to-peer (P2P) technologies to distribute media. After outlining the various causes of the conflict a set of potential solutions are presented. BackgroundP2P technologies are increasingly being used for legal distribution of media content. The generated traffic consists of bandwidth intensive file downloads as well as video streams, examples include Joost [2] and BBC's iPlayer [1]. For fixed broadband network operators this traffic has brought about a set of problems. Managed operator networks are usually partitioned into at least two parts. One partition provides guaranteed quality of service used for running traffic of value added services such as IPTV and VoIP and a best effort partition with no service guarantees provides data transport for end user Internet traffic. The outstanding issue is the introduction of contention for bandwidth in the best effort class in the operators network between regular Internet traffic (e.g., web surfing, email) and P2P traffic. The fair usage of the best effort section of the network is hence disrupted as users of P2P applications tend to use up a disproportionately greater share of the available bandwidth. The fair usage issue arises primarily due to the way P2P applications are designed, namely their greedy behavior whereby tens of parallel TCP sessions are simultaneously opened to speed up content delivery. Problem analysis and solution space2.1. Tromboning effect DSL Ethernet based broadband access networks consist of an aggregation network and an edge node connected to the core network. The aggregation network is made up of L2 switches as this helps ensure low cost and simplicity. The end users are connected to the aggregation network by means of access nodes (e.g., DSLAMs) and the aggregation network is connected to the core by edge nodes which perform IP routing. A widely used policy in Ethernet access networks is to force all unicast and broadcast traffic via the aggregation network to the edge nodes where routing, policing and traffic shaping is performed. This is implemented with a technology like MAC-forced forwarding [5].This common sort of setup brings about a so-called tromboning effect. The result of this effect is that end user traffic destined to another end user connected to the same access node would first be forced up to the edge node via the aggregation network after which it returns back via the aggregation network to the recipient end user. Moreover, the traffic between end users in the same subnet but connected to different access nodes must also go through the edge node. In this setup the P2P traffic between two users connected to the same access network would hence be sent twice via the aggregation network which is clearly suboptimal. Peer proximity and cachingSolutions addressing P2P traffic have included peer proximity awareness. The peers that are in close proximity are encouraged to exchange content between each other rather than fetching it from mor...

SoftEPC — Dynamic instantiation of mobile core network entities for efficient resource utilization

“…It can be seen from Figure 6(a) that the link mn has a very high utilization of up to 99% for TC-0 (note that node N hosts a P-GW). It is observed that this high utilization is caused by the tromboning effect [6], which is prevalent in centralized mobile network architectures. The utilization of this link drops dramatically to around 18% in TC-1 due to the loadaware optimized placement of softEPC functions in the GPNs.…”

BitTorrent Traffic Localization via Operator-Related Information

“…Two groups of solutions can be found here, that is locality awareness and network caching [2]. While the latter method can be performed by an operator alone, the former is done by peers with the carrier cooperation.…”

“…The unawareness of the underlying IP network related to P2P systems causes inoptimality of traffic flows in operators' networks [2], and is also responsible for undesirable interdomain (inter-carrier) traffic generating large costs. Additionally, random connectivity observed in those networks is suboptimal in the sense of the performance (download/completion time) that could be improved if P2P clients are connected having knowledge of their distance, network characteristics, geographical or networking localization.…”

Performance evaluation of P2P caches: Flash-crowd case

“…A significant portion of this traffic is exchanged between different domains. It is a real problem for ISPs (Internet Service Providers) [2], because of the possibility of congestion on inter-domain links and also due to high costs of such links.…”

“…In general, there are two basic groups of solutions that allow a decrease of the volume of the inter-domain traffic: locality (proximity) awareness and network caching [2]. In both cases a portion of the traffic is exchanged within ISP's domain instead of being transfered between various domains.…”