Inter-domain Routing Protocol Research Articles

Domain Constrained Multicast: A New Approach for IP Multicast Routing

One of major reasons why IP multicast has not been well deployed is the complexity of IP multicast routing. Since existing IP multicast routing protocols have been designed independently of IP unicast routing protocols, a router must maintain routing tables for both IP mutlicast and unicast routing. This is, in particular, a big burden for an inter-domain router. In addition, by using existing IP multicast routing protocols, we cannot realize an application that a sending host outside the designated domain sends IP multicast packets only towards the designated domain. To resolve above issues, we propose a new architecture for IP multicast, which is called Domain Constrained Multicast (DCM). In this architecture, IP multicast packets are forwarded to a border router of the designated domain using IP unicast routing. And then, IP multicast packets are delivered inside the designated domain using IP multicast. We propose an address format when realizing the DCM architecture using IPv6. We describe the extension of the DCM architecture for applying it to inter-domain IP multicast routing. Finally, we have compared the DCM architecture for inter-domain routing, with existing inter-domain IP multicast routing protocols such as MSDP and BGMP.

Automated provisioning of BGP customers

Manual configuration of IP routers is an expensive, time-consuming, and error-prone process. For large Internet service providers, establishing service for new customers is a major part of the financial cost of running the network. Increasingly, these customers want to exchange routing information with their provider(s) using the border gateway protocol (BGP), a complex and highly programmable interdomain routing protocol. This article describes how a provider can configure its connections to BGP-speaking customers, from the technical questions asked of new customers to the individual configuration commands applied to the production routers. We present a case study of a technical questionnaire and describe how the provider assigns unique identifiers such as IP address blocks, interface names, and access control list numbers on behalf of the customer. Next, we describe an example set of provisioning rules that use the customer-specific information to generate a sequence of configuration commands - a configlet - for adding the new connection to the network; our configuration rules are expressed using Cisco Internet Operating System (IOS) commands as an example. Then we describe a database schema for storing and accessing the customer-specific data, and discuss how to use a virtual view on this database to populate a template that captures the syntax of the router commands. Our provisioning system provides an inexpensive, efficient, and accurate way for a provider to configure connections to new BGP-speaking customers.

Towards a logic for wide-area Internet routing

Interdomain routing is a massive distributed computing task that propagates topological information for global reachability. Today's interdomain routing protocol, BGP4, is exceedingly complex because the wide variety of goals that it must meet---including fast convergence, failure resilience, scalability, policy expression, and global reachability---are accomplished by mechanisms that have complicated interactions and unintended side effects. The complexity of wide-area routing configuration and protocol dynamics requires mechanisms for expressing wide-area routing that adhere to a set of logical rules. We propose a set of rules, called the routing logic , which can be used to determine whether a routing protocol satisfies various properties. We demonstrate how this logic can aid in analyzing the behavior of BGP4 under various configurations. We also speculate on how the logic can be used to analyze existing configuration in real-world networks, synthesize network-wide router configuration from a high-level policy language, and assist protocol designers in reasoning about new routing protocols.

An Approach to Seeking Policy Disputes Based on Dispute Cycle Avoidance and Configuration Guideline

The Border Gateway Protocol (BGP) is the de facto interdomain routing protocol used to exchange network reachability information between ASes in the global Internet. However, Varadhan et al. [19] has shown that the conflict of BGP routing policies can cause BGP to diverge. This paper presents an approach to seek the set of conflict routing policies based on dispute cycle avoidance. The stable paths problem, a static formalism that captures the semantics of interdomain routing protocol, provides the theoretical foundation for this approach. And this approach draws on the simple path vector protocol to identify the dispute cycles that cause routing oscillation first, and then queries which routing policies lead to these cycles in a distributed manner. Finally, it determines conflict routing policies based on dispute cycle avoidance. Moreover, we present a method to determine the severity level of dispute routing policies based on AS relationships and configuration guidelines of routing policy presented by Gao and Rexford [4]. And this method can help Network administrators determine the top-priority routing policies to be fixed and improve the efficiency of debugging routing policies. In addition, a simulation instance is given in order to explain results of this method.

The stable paths problem and interdomain routing

Dynamic routing protocols such as RIP and OSPF essentially implement distributed algorithms for solving the shortest paths problem. The border gateway protocol (BGP) is currently the only interdomain routing protocol deployed in the Internet. BGP does not solve a shortest paths problem since any interdomain protocol is required to allow policy-based metrics to override distance-based metrics and enable autonomous systems to independently define their routing policies with little or no global coordination. It is then natural to ask if BGP can be viewed as a distributed algorithm for solving some fundamental problem. We introduce the stable paths problem and show that BGP can be viewed as a distributed algorithm for solving this problem. Unlike a shortest path tree, such a solution does not represent a global optimum, but rather an equilibrium point in which each node is assigned its local optimum. We study the stable paths problem using a derived structure called a dispute wheel, representing conflicting routing policies at various nodes. We show that if no dispute wheel can be constructed, then there exists a unique solution for the stable paths problem. We define the simple path vector protocol (SPVP), a distributed algorithm for solving the stable paths problem. SPVP is intended to capture the dynamic behavior of BGP at an abstract level. If SPVP converges, then the resulting state corresponds to a stable paths solution. If there is no solution, then SPVP always diverges. In fact, SPVP can even diverge when a solution exists. We show that SPVP will converge to the unique solution of an instance of the stable paths problem if no dispute wheel exists.

Security issues in control, management and routing protocols

The TCP/IP suite is the basis for today's Internet, yet it lacks even the most basic mechanisms of authentication. As usage of the Internet increases, its scarcity of built-in security becomes more and more of a problem. This paper describes serious attacks against Internet control and management protocols, with an emphasis on the ICMP protocol, as well as some of the well-known vulnerabilities of the inter-domain routing protocols. All the presented attacks have at least one common feature: they exploit intrinsic network security flaws. The paper also discusses various solutions to these security breaches, including the use of IPsec.

Persistent route oscillations in inter-domain routing

Hop-by-hop inter-domain routing protocols, such as border gateway protocol ( BGP) and inter-domain routing protocol ( IDRP), use independent route selection to realize domains' local policies. A domain chooses its routes based on path attributes present in a route. It is widely believed that these inter-domain routing protocols always converge. We show that there exist domain policies that cause BGP/IDRP to exhibit persistent oscillations. In these oscillations, each domain repeatedly chooses a sequence of routes to a destination. Complex oscillation patterns can occur even in very simple topologies. We analyze the conditions for persistent route oscillations in a simple class of inter-domain topologies and policies. Using this analysis, we evaluate ways to prevent or avoid persistent oscillations in general topologies. We conclude that if a hop-by-hop inter-domain routing protocol allows unconstrained route selection at a domain, the protocol may be susceptible to route oscillations. Constraining route selection to a provably “safe” procedure (such as shortest path) can reduce the number of realizable policies. Alternatively, a routing policy registry can help detect unsafe policies.

Intra- and inter-domain multicast routing protocols: A survey and taxonomy

A multicast routing protocol should be scalable, robust, use minimal network overhead, consume minimal memory resources, inter-operate with other multicast routing protocols, and be easy to implement. The mechanism used to manage the multicast group (participants join and leave throughout the multicast session) is an important issue when designing a protocol for multicast routing. Other design choices are influenced by the distribution of the participants over the routing domain (sparse or dense), the role of the participants in the group (source, receiver, or both), the number of groups and participants per group, and the requirements of the participants in terms of transmission delay. In this study a taxonomy of IP multicast routing protocols for dynamic groups will be presented. This taxonomy will be used to classify a surveyed set of intra- and inter-domain multicast routing protocols and to discuss successful protocol design regarding satisfaction of the multicast application's latency requirements as well as the network's resource consumption requirements.

A routing policy description language for the inter‐domain routing protocol

The inter-domain routing protocol (IDRP) is a strategic routing control protocol designed for wide use in OSI and the Internet. In IDRP, it is possible to impose fine route control reflecting local policies regarding the operation and management of networks; however, the configuration becomes extremely complicated with an increased number of policies. In this paper, a language is designed to describe routing control policies and various necessary knowledge configurations. A tool is installed for proper configuration from the policies and knowledge described by the design language. All knowledge necessary for the configuration is described by the “is-a” relation, and an inference engine is established based on the transitive law and succession relation. In addition, descriptions of framepolicies are made possible by using the “if-then” rule. © 1998 Scripta Technica. Electron Comm Jpn Pt 2, 80(6): 58–65, 1997

The viewserver hierarchy for interdomain routing: protocols and evaluation

We present an interdomain routing protocol based on a new hierarchy, referred to as the viewserver hierarchy. The protocol satisfies policy and type of service (ToS) constraints, adapts to dynamic topology changes including failures that partition domains, and scales well to a large number of domains without losing detail (unlike the usual scaling technique of aggregating domains into superdomains). Domain-level views are maintained by special nodes called viewservers. Each viewserver maintains a view of a surrounding precinct. Viewservers are organized hierarchically. To obtain domain-level source routes, the views of one or more viewservers are merged (up to a maximum of twice the levels in the hierarchy). We also present a model for evaluating interdomain routing protocols, and apply this model to compare our viewserver hierarchy against the simple approach where each node maintains a domain-level view of the entire internetwork. Our results indicate that the viewserver hierarchy finds many short valid paths and reduces the amount of memory requirement by two orders of magnitude.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Integrating security in inter-domain routing protocols

Network routing protocols work in a vulnerable environment. Unless protected by appropriate security measures, their operation can be easily subverted by intruders capable of modifying, deleting or adding false information in routing updates. This paper first analyses threats to the secure operation of inter-domain routing protocols, and then proposes various counter measures to make these protocols secure against external threats.

Effect of packet losses on end-user cost in internetworks with usage based charging

One of the most sensitive and controversial aspects in incorporating usage based charging in internetworks is the accounting of the packets that are dropped by transit domains during transit from source domain to destination domain. From the perspective of network users, lost packets are a waste of resources, and constitute additional burden on them. We use simulation to quantify the effect of packet losses on end-user cost in an internetwork consisting of transit domains with usage based charging policies. Our simulation shows that time based cost, packet based cost and byte based cost are differently affected by the changes in the packet loss probability of the inter-domain route. This will have implications for inter-domain routing protocols.

IDRP protocol analysis

IDRP is an inter-domain routing protocol that is based on the path-vector routing algorithm. This paper analysis storage complexity of the protocol and suggests possible local techniques for reducing it.

Secure control of transit internetwork traffic

Abstract When independent administrative domains (ADs) interconnect their networks, usage control mechanisms are needed to preserve the autonomy of each AD. Neither traditional network access control methods nor current internetwork routing protocols are well-suited to the enforcement of network usage policies. Consequently, new policy sensitive inter-domain routing protocols are under development. While these protocols are designed to enforce network policies, they raise new security-related concerns. This paper explores the design of transit control mechanisms for sensitive environments and investigates the performance overhead of the proposed mechanisms. After evaluating the application of stub-network access control and policy routing techniques, we describe and evaluate a secure policy routing protocol for transit ADs.