Una comprensión psicosocial de la juventud y los jóvenes

NAROS [Launois et al., 2003] is a mechanism that supports traffic engineering for un- equal load balancing distribution, without impacting the routing system. Thre draw- back of NAROS is that it requires modifications of end-hosts and does not preserve traffic flows across address changes [Launois et al., 2003; Savola and Chown, 2005; Dunmore et al., 2005].

Practical End-host Multihoming (PERM) [Thompson et al., 2006] enables flow sche- duling in multihomed hosts, by extending the Linux socket API. PERM also intro- duces the concept of collaborative multihoming, in which users share their Internet connection with others. Flows are distributed using a scheduling algorithm that con- siders flow volume, load of a link and the respective RTT. Nonetheless, such metrics are not measured and are based on estimation techniques.

Strawman architecture [Habib et al., 2007] also modifies the Linux socket API to perform flow distribution at the session layer. Flows are stripped over multiple con- nections to maximize throughput and minimize delay, jitter and loss. Multimedia applications are also supported, by allowing in-order delivery but without transport guarantees. The drawback of this architecture is the fact of using IP addresses for location and identification simultaneously.

Forwarding directive, Association, and Rendezvous Architecture (FARA) [Clark et al., 2003] follows a location/identifier split approach that optimizes end-host mobil- ity support by using rendezvous mechanisms. In FARA, no global namespace exists, instead the association IDs, the entity names and the end system address are used to establish communication between entities. FARA requires modifications in the net- work (i.e. for mapping) and on end-hosts, which does not facilitate its deployment [Ahlgren et al., 2005].

Layered Naming Architecture (LNA) [Balakrishnan et al., 2004] is a proposal that modifies end-hosts and the naming resolution system. LNA introduces a delegation system, where middleboxes stand-up on behalf of other entities, for instance, NAT routers or firewalls. Nonetheless, LNA introduces overhead with mappings, as they

2.6 End-host Multihoming

are performed twice.

Table 2.5: End-host multihoming proposals.

MH-Multihoming, OS-Operating System, Sim-Simulators.

Protocol MH Goals Strengths Flaws Implementation

R U L F Sim OS HIP1 √ _{X X X IP family} agnostic Deployment issues HIPSim++a _InfraHIPb HIP SIMA1 √ √ √ √ Security Limited policy specifica- tion – –

SHIM61 √ _{X X X Easier de-}

ployment than HIP Mobility and security issues REAP in OPnetc LinShim6d NAROS2 √ X √ X Load sharing for unequal paths No LoC/ID split. – – PERM3 √ X √ √ Security No LoC/ID split. – – Strawman3 √ _X √ √ _{Security No} LoC/ID split. – –

LNA1 √ X X X Delegation Overhead

in updates

– –

FARA1 √ √ _{X X Supports}

mobility

– –

a_{[Bokor, 2013]} b_{[Gurtov, 2013]} c _{[Khan, 2013]} d _{[INL, 2013]} 1_{Loc/ID split} 2_{Routing/TE decouple} 3_{Flow Strip} h

The pros and cons of the reviewed proposals for end-host multihoming support are summarized in Table 2.5, according to the multihoming goals fulfillment.

Identifier (Loc/ID) split is one of the approaches aiming to break the dual role of IP addresses. SHIM6 [Nordmark and Bagnulo, 2009] is a locator-identifier multihoming approach that adds a shim layer between the network and transport layers. SHIM6 uses REAP [Arkko and van Beijnum, 2009] to perform the detection of invalid loca- tors and recover in an application-independent fashion. SHIM6 also includes security mechanisms to enable the protection of nodes identity. Nevertheless, SHIM6 must be combined with other protocols, such as MIPv6, to provide mobility support.

HIP [Gurtov, 2008] is an identity protocol that also decouples identifiers from lo- cators. Its multihoming support relies on two approaches, one that resorts to the in- clusion of new options in the HIP messages, that is, the LOCATOR parameter, and another that employs a RendezVous Server that maintains the mapping between iden- tifiers and locators. Extensions to HIP [Pierrel et al., 2007] introduce load sharing and flow distribution support. The RendezVous servers are modified to store flow policies and HIP messages are updated to convey policies. This proposal extends the HIP4BSD implementation [Pekka Nikander, 2008], but is not publicly available.

NAROS [Launois et al., 2003] explores a routing/TE decoupling approach by im- plementing a server that holds the information of the appropriate source address a multihomed host must use when communicating with a certain peer. This approach alleviates the changes on routing systems (network part) but stresses the modification on the host part, as each node must query the server for each new communicating peer. With a different approach, LNA [Balakrishnan et al., 2004] introduces modifica- tion at the network side to accommodate mappings.

The strawman architecture [Habib et al., 2007] and PERM [Thompson et al., 2006] explore flow stripping mechanisms. Whilst such approaches have fine-grained capa- bilities (e.g. support of flow distribution according to policies), they require applica- tions to be modified to support multihoming. These proposals are implemented by extending the functionalities of the Linux sockets API.

2.7

End-site Multihoming

This section overviews end-site multihoming proposals that are tailored for networks. Such proposals are defined according to Definition. 2.3, introduced in subsection 2.1.3. End-site multihoming has gained more attention than end-host multihoming, mainly due to the routing scalability problems that the Internet is facing (e.g. high growth in the core routing). End-site multihoming approaches can be classified in three major types: First, address rewriting approaches, which change addresses in

2.7 End-site Multihoming

packets; Second, hierarchical approaches, which structure networks to address scal- ability; Third, mapping and encapsulation approaches, which implement locator/i- dentifier (Loc/ID) split paradigm, and as such, require mapping facilities to retrieve locator from identifiers, or vice-versa. Current IP routing architectures in Internet, such as Border Gateway Protocol (BGP) [van Beijnum, 2002], are not overviewed as these do not support Loc/ID paradigm.