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VoxTechnologies
Enterprise Network Series
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Alcatel 7420 Edge Services Router (ESR)
Frequently Asked Questions
Q. What is the Alcatel 7420 Edge Services Router (ESR)?
A. The Alcatel 7420 Edge Services Router (ESR) is a business services IP edge
router for service providers that redefines the meaning of wire-speed
performance. The 7420 ESR combines the intelligence to create and deliver the
most advanced business IP services at wire-speed with a scalable platform
providing high-density aggregation and linear performance growth. Also, the 7420
ESR provides carrier grade reliability and resiliency options that match service
expectations for emerging, mission-critical, IP-based business applications.
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Q. Who would use the Alcatel 7420 ESR?
A. The 7420 ESR targets the IP aggregation router market. It was optimized for
business subscribers and was built from the ground up to offer carrier-grade
reliability. The primary targets for the 7420 ESR are:
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Tier 1 ISPs including ISP divisions within full service providers, Tier 2
ISPs and PTTs that must aggregate hundreds to thousands of leased line
connections per point of presence (PoP)
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Regional service providers such as competitive local exchange carriers
(CLECs), incumbent local exchange carriers (ILECs), inter-exchange carriers
(IXCs) and regional Bell operating companies (RBOCs) that require
leased-line aggregation
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Service providers that need to tailor-make high-value IP services for
enterprise customers
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Data-centric business services groups within full service providers that
have decided to provide IP services
The 7420 ESR supports both T1 and E1 interfaces and so can provide aggregation
for customers worldwide.
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Q. Where is the Alcatel 7420 ESR positioned in a service provider's
network?
A.
The 7420 ESR is designed to aggregate large numbers of leased lines at the edge
of a service provider's core network-the Central Office (CO) or PoP-while
maintaining wire-speed throughput with services on. It can offer services such
as quality of service (QoS) and multiprotocol label switching/virtual private
network (MPLS/VPN), and then hand off traffic to an ISP's core router such as an
Alcatel 7770 or Alcatel 7670.
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Q. What should service providers expect from the Alcatel 7420 ESR?
A. The 7420 ESR is designed to meet service providers' expectations. It
offers:
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Intelligence: the ability to define, provision and manage advanced,
differentiated services
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Performance: wire speed delivery point for advanced network services
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Scalability and Density: on demand aggregation of customer circuits and
sessions in the least space
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High Availability: non-stop networking with carrier grade reliability; no
single point of failure
The 7420 ESR helps service providers pursue new revenue opportunities and gain a
competitive edge through its ability to offer differentiated services. At the
same time, it improves operating margins with its high density and reduces total
cost of ownership.
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Q. What are the common services offered over the Alcatel 7420 ESR?
Internet access-retail and wholesale: Internet access is carriers and service
providers' primary business IP service offering. It includes retail Internet
access from a service provider to small, medium or large enterprises and
Wholesale Internet access from a service provider to downstream ISPs.
Value-added access services include content and web hosting services.
Value-added business IP services: Service providers can realize new
revenues by offering advanced business IP services enabled by the Alcatel 7420
ESR. Some of the performance-optimized IP services in the ESR include:
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CoS/QoS: based on multi-field classification and DSCP, this allows ISPs to
differentiate between business-class data service and economy class as well
as VoIP and video
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Multicast services
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IP/VPN-MPLS and VR-which allows ISPs to offer a total private network
package to businesses that want to outsource management of their corporate
WAN network with defined Service Level Agreements (SLAs) over IP
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Access-rate control using CIR
IP aggregation: The 7420 ESR terminates and aggregates subscriber lines
from a diverse set of interfaces to be delivered to the network core.
Subscriber access networks include:
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SONET/SDH access rings for PPP and frame relay
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ATM multiservice networks aggregating PPP, frame relay and/or cell relay
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ATM interfaces for DSLAM DSL attachment
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ATM interfaces for broadband fixed wireless base station attachment
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Aggregation of application specific IP gateways, including BRAS, RAS, VoIP,
video via PoS, ATM or Gigabit Ethernet
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Q. Where does the Alcatel 7420 ESR fit within Alcatel's end-to-end product
portfolio?
A. The 7420 ESR complements Alcatel's product portfolio by strengthening IP
capabilities at the network edge. For example, it works with the Alcatel
7770/7670 core network products by providing leased-line and service aggregation
with complex lookup and classification. It applies differentiated services,
including QoS, access lists, committed access rate [CAR] and MPLS to every
packet before the packet is handed off to the core router. By specializing in
aggregation and services deployment, the 7420 ESR enables the core router to
focus on its primary task of backbone/core routing. Also, Alcatel's superior
network and services management software spans the entire network, allowing
service providers to define, provision and manage new revenue generating
services while optimizing performance.
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Q. What's the difference between the Alcatel 7420 ESR and a Broadband
Remote Access Server (BRAS)?
A. The 7420 ESR is a next generation IP router that can be used to offer
business IP services, including Internet access and IP VPNs. A BRAS, such as the
Alcatel 7411, is primarily used to offer residential Internet Access services.
So, the 7420 ESR complements the 7411 BRAS and can aggregate traffic from more
than one of them.
The 7420 ESR value-adds include:
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Support for industry-grade BGP-4: a robust, high performance BGP-4
implementation is a must to support a high number of external and internal
BGP peering sessions
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Supports for large routing tables: the current RIB size is 128,000
entries, scalable to 256,000 entries to support the entire Internet address
space with its summarized prefixes
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Wire-speed packet forwarding: the 7420 ESR has an aggregate forwarding
rate of 18 Mpps, thanks to its distributed network processor based
architecture
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Q. What are the high availability features on the Alcatel 7420 ESR?
A. The 7420 ESR provides high-reliability and high-availability-the elements
of non-stop networking. It is designed for hardware and software resiliency,
an ability to detect and recover from spontaneous failures, plus the ability
to perform scheduled upgrades or servicing. The system architecture and the
serviceable assemblies that connect to it employ the following hardware
redundancy and high-reliability features:
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Hot Swappable: all field replaceable, non-service affecting units
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Power: 1+1
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Cooling (Fan): N+1
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Switch fabric: 1+1
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System service module: 1+1
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SONET/SDH APS protection: 1+1
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Interface Redundancy: N+1, 1+1
High-availability is also a feature of the software design of the 7420 ESR,
thanks to its modular design. In addition, major system tasks such as routing,
forwarding, and system management and configuration, 
each run on separate processors and memory systems. The control and data planes
are separated throughout the system. This contributes in important ways to
reliability and performance predictability. It also ensures that in spite of
fabric, line card or control card failure, the system management software will
be able to communicate with the affected card. The result, here, is reliable
fault detection and isolation.
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Q. Will the primary line card automatically cut over to the secondary line
card in the event of a failure?
A. Yes. In the event of a failure, the software and hardware will
automatically switch over to the secondary line card, minimizing service
disruption. The master line card actively monitors the health of the secondary
line card and sends it the configuration information necessary to take over when
needed.
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Q. Are clusters of separate router shelves recommended for redundancy?
A. No. We believe that the present practice of clustering nodes is
sub-optimal and is in place primarily because of the historical lack of carrier
grade redundancy and resiliency features in routers. The 7420 ESR has
carrier-grade reliability designed into all aspects of the architecture with
control, fabric and line interface redundancy, separation of processing
resources, and reliable software design. Clusters of nodes are used in
conjunction with protocols such as VRRP or HSRP to allow a single chassis to be
circumvented in the event of failure. This option is costly, since it requires
more interfaces for the inter-node links and, as a result, provides lower
density than might otherwise be expected. When the 7420 ESR is deployed in a
redundant configuration, the components are protected within the chassis. This
averts the need to provide separate chassis for redundancy.
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Q. What characterizes the Alcatel 7420 ESR architecture?
A.
The 7420 ESR has an architecture designed to provide an ideal balance of
intelligence, to deliver next generation business IP services, scalability, for
investment protection and low operating costs, and reliability, to provide
carrier-grade, high availability performance. The architecture separates the
data and control planes to provide wire-speed performance, which does not
deteriorate when new IP services are enabled. Understanding that software
service requirements change over time and that technology standards continue to
evolve, the 7420 ESR's distributed NP architecture supports easy software
upgrades to provision and adapt new, enhanced software services and standards as
they are developed, and so provide investment protection. In addition, the 7420
ESR is designed to protect against any single-point failures. Power supplies,
cooling (fans), switching fabric module and the system services module are all
hot-swappable. The 7420 ESR is designed to take advantage of Alcatel's reliable,
carrier-grade network management software. By combining highly reliable hardware
and software Alcatel delivers a first-class edge services appliance that will be
reliable for years to come.
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Q. What are the key features and benefits of the Alcatel 7420 ESR's
architecture?
A. The 7420 ESR uses a NP-based architecture to deliver extremely high
throughput for thousands of leased-line connections, with IP services enabled
on every connection. With the separation of the data and control planes, and
the network processor on the line cards, the 7420 ESR also provides linear
growth and scalability with no compromise on performance. The key features
include:
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Intelligence, to provide parallel forwarding and policy application to
create new revenue opportunities and provide a competitive edge
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Wire-speed forwarding for the most complex, policy-based IP service
offerings
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Intelligence and flexibility to create advance, IP services leveraging
DiffServ, MPLS and advanced IP traffic management technologies
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Scalability, to reduce operating costs and protecting investment
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40 Gb/s, upgradable to 80 Gb/s
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unique distributed I/O + Network Processor combination
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high-density aggregation, scalable to thousands of T1s and E1s per rack.
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Reliability, to provide carrier grade performance with high availability
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NEBS Level 3 compliance, control, fabric, power and fan redundancy, 1+1
and 1+N interface redundancy, SONET APS, hot swap
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Q. What are Network Processors (NPs), and why are they better than
alternative technologies?
A. The NP is a relatively recent innovation that brings the speed of an ASIC
and the flexibility of a conventional CPU to bear on the scalability and
performance requirements of a next-generation router. The NP is a highly
integrated device designed to accelerate networking operations. It is
characterized by high I/O bandwidth, an array of hardware assistance elements,
and, most important, programmability. Programmability distinguishes an NP from a
custom network ASIC. The NP offers more than a simple ability to write to a
chip's registers to configure features. It has a machine language that enables
hardware accelerators and the development of custom algorithms that inspect line
rates and modify network traffic. As new services are defined or new standards
evolve, they can be provided through a quick software upgrade, without hardware
changes. In addition, an NP is often characterized by an array of processing
elements that can distribute workload in the NP and by parallel execution of
algorithms. An NP, like an ASIC, sits in the data path of a networking device,
and is optimized to perform or enable the classification, filtering, forwarding,
marking and policing functions.
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Q. Do feature modifications require hardware changes?
A. No. Unlike hardware- or application-specific ASIC-based switching models,
the 7420 ESR's network processors are programmable. Adding new services or
enhancing existing services are done through a software download. This reduces
the time and money it takes to implement network improvements or enhancements,
protecting your investment in the Alcatel 7420 ESR.
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Q. Does provisioning and enabling additional features affect the
performance of the Alcatel 7420 ESR?
A. No. Unlike software routers with centralized forwarding engines, the 7420
ESR has a distributed NP-based architecture that maintains forwarding rates even
with provisioning of new services. This ensures a no-compromise, service-speed
performance.
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Q. Are the Alcatel 7420 ESR's I/O and Media Interface modules
hot-swappable?
A. Yes, the interface modules can be installed or removed with the system
powered on. In a redundant configuration, after the traffic has switched over,
the idle line card can be replaced without interrupting the rest of the system.
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Q. Describe the Alcatel 7420 ESR's Network Equipment Building Systems
(NEBS) compliance.
A. The 7420 ESR system was designed to meet NEBS Level 3 requirements for
products installed in a telco transmission equipment facility.
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Q. What interface types can the Alcatel 7420 ESR aggregate?
A. The ESR supports virtually any combination of T1/E1, T3/E3 and OC-n/STM-n
interfaces, as well as FR and ATM services.
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Q. How many connections will the Alcatel 7420 ESR support?
A. The Alcatel 7420 ESR can scale to 9,000 T1 and 6,500 E1 connections per
seven-foot rack.
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Q. What types of interface cards will the Alcatel 7420 ESR support?
A. The ESR supports the following network interface cards:
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6-port clear channel DS3
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6-port channelized DS3
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4-port POS OC-3c/STM-1 (SR/IR/LR interface options)
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4-port ATM OC-3c/STM-1 (SR/IR/LR interface options)
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1-port POS OC-12c/STM-4 (SR/IR/LR interface options)
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1-port ATM OC-12c/STM-4 (SR/IR/LR interface options)
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Channelized OC-3/OC-12 (DS0/DS1/DS3)
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Channelized STM-1/STM-4 (n*64/E1/E3/DS3)
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Gigabit Ethernet (LX and SX interface options)
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Q. What level of channelization does the Alcatel 7420 ESR support on its
subscriber modules?
Channelized T3 module: The 7420 ESR channelized T3 card supports six
channelized DS3 ports per card. Each DS3 supports full-rate or subrate DS3
orDS1. Each T3 line card can support up to 168 T1 connections.
Channelized OC-12 module: For ISPs with available optical cable, the ESR
supports a channelized OC-12 line card. The channelized OC-12 module supports
full-rate and subrate DS3, DS1, DS0, and NxDS0 rates. The OC-12 line card
supports up to 12 independent channelized DS3 signals for 336 DS1s per card,
3024 DS1s per chassis with one uplink card and nine channelized OC-12 cards, or
more than 9000 DS1s per seven-foot rack.
Channelized STM-x module: The channelized STM-x will be available in a 4-port
STM-1 or single port STM-4 variant. The channelized STM-1 card supports
synchronous digital hierarchy (SDH) STM-1 (155 Mbps) channelized down to the DS0
level. The channelized STM-1 card is capable of supporting 252 E1 connections,
with a fully configured 7420 ESR supporting more than 2268 E1s per system or
over 6500 E1s per rack.
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Q. What uplink modules does the Alcatel 7420 ESR support?
Single port OC-12/STM-4 PoS module: This module supports up to 622 Mb/s
throughput over a standard SONET/SDH interface with a single-mode fiber,
intermediate-reach SC connector.
Single-port OC-12/STM-4 ATM module: The OC-12 ATM line card is a full-size
single-mode intermediate-reach line card that provides a 622 Mb/s SONET/SDH
connection to ATM networks.
Single-port Gigabit Ethernet module: This interface is a standards-based
802.3z Gigabit Ethernet implementation supporting full-duplex traffic along with
hot-swappable SX or LX options.
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Q. Does the Alcatel 7420 ESR support POS and ATM?
A. Yes. The 7420 ESR supports POS and ATM on the OC-n/STM-n interface
modules.
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Q. Does the Alcatel 7420 ESR's channelized sub-interface support frame
relay and PPP?
A. Yes, the 7420 ESR does support frame relay and PPP.
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Q. Which software services does the Alcatel 7420 ESR support?
A. The 7420 ESR supports L# routing protocols like BGP-4, OSPF, IS-IS and
RIPv2. In addition, it supports a comprehensive list of features for offering
services based on IP QoS/CoS, MPLS, DiffServ, MPLS-based IP VPNs, IP Mulitcast.
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Q. How does the Alcatel 7420 ESR's software architecture scale to meet
future requirements and evolving standards?
A. Evolving networking protocols, new network services and unique customer
requirements pose the need for a unique and flexible software architecture. The
7420 ESR features such an architecture, employing Network Processors (NPs). NPs
deliver the performance of custom ASICs with the flexibility of a software-based
solution. The NPs are distributed. Their use of microcode enables the 7420 ESR
to keep pace with rapid changes in technology and service needs while protecting
customers' existing technology investments. Services and I/O modules can be
reprogrammed and updated by loading new software instead of replacing chips or
entire boards. Its design gives the 7420 ESR great flexibility. For example,
Multi-Protocol Label Services (MPLS) and Differentiated Services (DiffServ) are
important but evolving standards. Both are supported by the system, but each
standard is likely to change over time. As changes in the standards manifest
themselves, they can be incorporated in software upgrades that update each
module's firmware with the improvements.
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Q. Describe the MPLS capability and features supported on the Alcatel 7420
ESR.
A. Service Providers have adopted MPLS to solve problems that could not be
solved with traditional IP routing. It is likely that some deployment scenarios
may require LER functionality to set up traffic engineered LSP's from the 7420
ESR. In some scenarios, the 7420 ESR may be deployed to act as a transit LSR.
The 7420 ESR supports LER and LSR capabilities to enable applications like
traffic engineering and MPLS-based VPNs.
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Q. What MPLS applications and features are supported by the Alcatel 7420
ESR?
A. The following MPLS applications and features are supported:
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Traffic engineering
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IP VPNs
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Fast rerouting
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Constraint based routing and path computation
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MPLS and QoS
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Q. How is the Forwarding Equivalence Class (FEC) defined and what options
are supported on the Alcatel 7420 ESR?
These classification parameters are also used to define the FEC. FEC information
is a key component for MPLS performance and QoS. The FEC is the information used
to identify a service and associated CoS. The 7420 ESR can establish a LSP per
existing FEC using standardized Label Distribution Protocol (LDP). The 7420 ESR
supports LDP downstream on demand as the signaling mechanism for MPLS. It also
supports conservative label retention mode when it receives unsolicited label
assignment messages.
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Q. What are the Alcatel 7420 ESR's network and services management
strategies?
A. The network and service management for the Alcatel 7420 ESR is consistent
and integrated with Alcatel's overall strategy. At the element level, the
Alcatel 5520 SNMP element manager is used to manage the 7420 ESR. The 7420 ESR
is also managed using an industry-standard command line interface (CLI), which
hence reduces the cost of training network administrators. The 7420 ESR is also
managed by the SNMP. At the network level, it is integrated with the Alcatel
5620 Network Manager and the ALMAVision IP Traffic Engineering tool. At the
service level, it communicates with Alcatel's family of management products.
This includes the 5740 Service Subscription Manager, the 5710 CORBA Service OSS
Interface and the 5730 VSM for IP VPNs.
Key features include:
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Single step provisioning from customer to service edge
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Intuitive sophisticated web-based GUI
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Quickly identifies customers and services affected by network faults
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IP VPN service provisioning
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Generates traffic, error, congestion and SLA reports
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Graphical view of topology
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Support for configuring links between routers
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Support for configuring routers
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MPLS Traffic Engineering tool
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Monitor IP objects (routers, IP links, LSPs)
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