Specifications

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1.2 JUNOS Internet Software: Traffic Engineering and Control
Protocols and software tools, which are used to control and direct network traffic,
are critical to an Internet backbone routing solution. In fact, software control is
made more important by the fact that the size and complexity of backbone
networks are increasing at a time when service providers are looking to
differentiate themselves through value-added service offerings. To provide a
foundation for control, the M-xxx Routing Engine features JUNOS Internet
Software, which offers a full suite of Internet-scale, Internet-tested routing
protocols.
The JUNOS software features implementations of the BGP4, IS-IS, OSPF,
MPLS, DVMRP, and PIM protocols. A Juniper design team developed all
protocols in-house with extensive experience in addressing the scaling issues of
rapidly growing Internet backbone providers.
JUNOS software features a modular design, with separate programs running in
protected memory space on top of an independent operating system. Unlike
monolithic, unprotected operating system designs, which are prone to system-
wide failure, the protected, modular approach improves reliability by ensuring that
modifications made to one module have no unwanted side effects on other
sections of the software. In addition, having clean software interfaces between
modules facilitates software development and maintenance, enabling faster
customer response and delivery of new features.
The JUNOS software also provides a new level of traffic engineering capabilities
with its implementation of Multi-Protocol Label Switching (MPLS). Developed in
conjunction with the emerging IETF standard, Juniper MPLS offers enhanced
visibility into traffic patterns and the ability to control the path traffic takes through
the network. Path selection enables providers to engineer traffic for efficient use
of network capacity and avoidance of congestion. MPLS and traffic engineering
will become a crucial tool for providers as they scale their networks.
The JUNOS software features include:
§ Full-scale implementation of BGP4 with route reflectors, confederations,
communities, route flap damping, and MD5 BGP authentication
§ A flexible and scalable policy implementation for filtering and modifying route
advertisements
§ Scalable IS-IS and OSPF for filtering and modifying route advertisements
§ PIM Sparse Mode and Dense Mode, DVMRP, MSDP and IGMP for multicast
§ MPLS with LDP and RSVP extensions for traffic engineering
§ Configuration management features for enhanced usability
§ Secure remote access with SSH (USA version only)
1.2.1 JUNOS Internet Software: Class-of-Service Flexibility
The Juniper routers have been designed for a variety of class-of-service
applications. The queuing mechanism is based on a weighted round-robin
selection among four queues on outgoing interfaces. Three drop profiles per
Flexible PIC Concentrator (FPC) are available to control the rate of packet drops
based on utilization of buffer capacity. A Random Early Detection (RED)
algorithm handles congestion management based on these profiles, ensuring the
proper execution of the provider’s policy.
The Juniper routers give providers full flexibility in setting class-of-service levels
for customers. Service levels can be based on destination address, physical input
port, IPv4 precedence bits, MPLS CoS bits, virtual circuit, next-hop address,
and/or encapsulation type. The Juniper routers also offer the ability to overwrite
the precedence of incoming packets. In addition, a token-bucket mechanism has
been implemented on input to allow rate policing, enabling CIR (Committed
Information Rate)-type service for customers. Finally, a leaky-bucket mechanism
provides rate shaping on output ports.
1.2.2 Random Early Detection for Congestion Management
Random Early Detection (RED) provides network operators with the ability to
flexibly specify traffic handling policies to maximize throughput under congestion
conditions. RED works in conjunction with robust transport protocols (e.g. TCP) to
intelligently avoid network congestion by implementing algorithms which:
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Chassis MgmtChassis Mgmt
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