1,595 research outputs found
IP Fast Reroute with Remote Loop-Free Alternates: the Unit Link Cost Case
Up to not so long ago, Loop-Free Alternates (LFA)
was the only viable option for providing fast protection in pure
IP and MPLS/LDP networks. Unfortunately, LFA cannot provide
protection for all possible failure cases in general. Recently, the
IETF has initiated the Remote Loop-Free Alternates (rLFA)
technique, as a simple extension to LFA, to boost the fraction
of failure cases covered by fast protection. Before further stan-
dardization and deployment, however, it is crucial to determine
to what extent rLFA can improve the level of protection in a
general IP network, as well as to find optimization methods to
tweak a network for 100% rLFA coverage. In this paper, we take
the first steps towards this goal by solving these problems in the
special, but practically relevant, case when each network link is
of unit cost. We also provide preliminary numerical evaluations
conducted on real IP network topologies, which suggest that rLFA
significantly improves the level of protection, and most networks
need only 2 â 3 new links to be added to attain 100% failure
case coverage
Fast emergency paths schema to overcome transient link failures in ospf routing
A reliable network infrastructure must be able to sustain traffic flows, even
when a failure occurs and changes the network topology. During the occurrence
of a failure, routing protocols, like OSPF, take from hundreds of milliseconds
to various seconds in order to converge. During this convergence period,
packets might traverse a longer path or even a loop. An even worse transient
behaviour is that packets are dropped even though destinations are reachable.
In this context, this paper describes a proactive fast rerouting approach,
named Fast Emergency Paths Schema (FEP-S), to overcome problems originating
from transient link failures in OSPF routing. Extensive experiments were done
using several network topologies with different dimensionality degrees. Results
show that the recovery paths, obtained by FEPS, are shorter than those from
other rerouting approaches and can improve the network reliability by reducing
the packet loss rate during the routing protocols convergence caused by a
failure.Comment: 18 page
Real-time bandwidth encapsulation for IP/MPLS Protection Switching
Bandwidth reservation and bandwidth allocation are needed to guarantee the protection of voice traffic during network failure. Since voice calls have a time constraint of 50 ms within which the traffic must be recovered, a real-time bandwidth management scheme is required. Such bandwidth allocation scheme that prioritizes voice traffic will ensure that the voice traffic is guaranteed the necessary bandwidth during the network failure. Additionally, a mechanism is also required to provide the bandwidth to voice traffic when the reserved bandwidth is insufficient to accommodate voice traffic. This mechanism must be able to utilise the working bandwidth or bandwidth reserved for lower priority applications and allocate it to the voice traffic when a network failure occurs
SWIFT: Predictive Fast Reroute
Network operators often face the problem of remote outages in transit networks leading to significant (sometimes on the order of minutes) downtimes. The issue is that BGP, the Internet routing protocol, often converges slowly upon such outages, as large bursts of messages have to be processed and propagated router by router.
In this paper, we present SWIFT, a fast-reroute framework which enables routers to restore connectivity in few seconds upon remote outages. SWIFT is based on two novel techniques. First, SWIFT deals with slow outage notification by predicting the overall extent of a remote failure out of few control-plane (BGP) messages. The key insight is that significant inference speed can be gained at the price of some accuracy. Second, SWIFT introduces a new data-plane encoding scheme, which enables quick and flexible update of the affected forwarding entries. SWIFT is deployable on existing devices, without modifying BGP.
We present a complete implementation of SWIFT and demonstrate that it is both fast and accurate. In our experiments with real BGP traces, SWIFT predicts the extent of a remote outage in few seconds with an accuracy of ~90% and can restore connectivity for 99% of the affected destinations
Segment Routing: a Comprehensive Survey of Research Activities, Standardization Efforts and Implementation Results
Fixed and mobile telecom operators, enterprise network operators and cloud
providers strive to face the challenging demands coming from the evolution of
IP networks (e.g. huge bandwidth requirements, integration of billions of
devices and millions of services in the cloud). Proposed in the early 2010s,
Segment Routing (SR) architecture helps face these challenging demands, and it
is currently being adopted and deployed. SR architecture is based on the
concept of source routing and has interesting scalability properties, as it
dramatically reduces the amount of state information to be configured in the
core nodes to support complex services. SR architecture was first implemented
with the MPLS dataplane and then, quite recently, with the IPv6 dataplane
(SRv6). IPv6 SR architecture (SRv6) has been extended from the simple steering
of packets across nodes to a general network programming approach, making it
very suitable for use cases such as Service Function Chaining and Network
Function Virtualization. In this paper we present a tutorial and a
comprehensive survey on SR technology, analyzing standardization efforts,
patents, research activities and implementation results. We start with an
introduction on the motivations for Segment Routing and an overview of its
evolution and standardization. Then, we provide a tutorial on Segment Routing
technology, with a focus on the novel SRv6 solution. We discuss the
standardization efforts and the patents providing details on the most important
documents and mentioning other ongoing activities. We then thoroughly analyze
research activities according to a taxonomy. We have identified 8 main
categories during our analysis of the current state of play: Monitoring,
Traffic Engineering, Failure Recovery, Centrally Controlled Architectures, Path
Encoding, Network Programming, Performance Evaluation and Miscellaneous...Comment: SUBMITTED TO IEEE COMMUNICATIONS SURVEYS & TUTORIAL
Efficient Algorithms to Enhance Recovery Schema in Link State Protocols
With the increasing demands for real-time applications traffic in net- works
such as video and voice a high convergence time for the existing routing
protocols when failure occurred is required. These applications can be very
sensitive to packet loss when link/node goes down. In this paper, we propose
two algorithms schemas for the link state protocol to reroute the traffic in
two states; first, pre-calculated an alternative and disjoint path with the
primary one from the source to the destination by re-routing traffic through
it, regardless of the locations of failure and the number of failed links.
Second, rerouting the traffic via an alternative path from a node whose local
link is down without the need to wait until the source node knows about the
failure. This is achieved by creating a new backup routing table based on the
original routing table which is computed by the dijkstra algorithm. The goal of
these algorithms is to reduce loss of packets, end-to-end delay time, improve
throughput and avoiding local loop when nodes re-converge the topology in case
of failure.Comment: 15 page
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