Juniper HW Overview

I. Juniper® Routers and Junos™

I.A Juniper® Routers Hardware and Features

1. Routers Types

Juniper routers are primarily available in the following series:

· E-Series,

· J-Series,

· M-Series, and

· T-Series.

However, here we discuss overview of different series of routers and architecture and functioning of a typical M-Series router. A Juniper router runs JUNOS™ networking software and supports Internet Protocols. The following discussion would enable us to understand the hardware and software components of a Juniper router in more detail.

E-Series Routers: The E-series network router support a suite of Internet routing protocols, including BGP-4, IS-IS, OSPF, and RIP. E-series edge routers ideal for service providers that operate high-capacity POPs.

The E-series family of Broadband Services Routers provide large bandwidth capacities and advanced QoS capabilities, and designed to act as the aggregation point where service providers accept and authenticate remote connections from customers.

The E-series family provides bandwidth capacity options from 5, 10, or 40 Gbps up to 100 and 320 Gbps and supports high-port density WAN interfaces in a compact package.

Interface options include OC-3/STM-1, OC-12/STM-4, OC-48/STM-16, Fast Ethernet, and Gigabit Ethernet, as well as channelized DS-1, DS-3, E1, and E3.

J-Series: The J-series Services Router hardware platform that is suitable for smaller sites, including remote, branch, and regional offices. The J-series routers offer advanced routing, QoS, security, and management policies.

M and T-Series: Juniper® enterprise level routers are primarily available in a. M-series and b. T-series routers. T-series and M-series platforms share a common architecture that separates routing, forwarding, and services functions to facilitate scalability and security. The M-series family can be deployed in both the service-provider environment and high-end enterprise environments.

The routers offer filtering, policing, rate limiting, and sampling where as the T-series platforms use the T-series Internet Processor for route lookups and notification forwarding.. The M-Series routers are available in M5, M10, M20, M40, M160, and others. The T-series routers are available in T320 and T-640.

A typical chassis for M5 router is shown below (This is given for educational purpose only, please refer official website for exact information). The front and rear views of M5 Internet Router are given.

M5 Chassis Front Panel:

M5 Chassis: Rear Panel:

The rear panel of the M5 router is shown in the above figure. It contains a routing engine, forwarding engine, and power supplies. These will be discussed in the coming sections.

2. Hardware components

The major hardware components in a Juniper routers are given below:

Router Chassis:

Chassis is a rigid sheet metal, which contains all other router components. Please refer to the typical router chassis below.

Front Panel REAL PANEL

Flexible PIC Concentrators:

The FPCs contains the Physical interface Cards (PICs) used in the router and connect them to other router components. FPCs install into the front of the router in either a vertical or horizontal orientation, depending on the router.

Physical Interface Cards:

PICs are used to connect to a network media. PICs receive incoming packets from the network and transmit outgoing packets to the network. PICs encapsulate the packets received from the FPCs before transmitting them to the network.

Routing Engine:

The Routing Engine consists of an Intel-based PCI platform running the JUNOS software. The Routing Engine maintains the routing tables used by the router. Routing Engine consists of a CPU; SDRAM for storage of the routing and forwarding tables and other processes; a compact flash disk for primary storage of software images, configuration files, and microcode; a hard disk for secondary storage; a PC card slot (on some M40 routers, a floppy disk) for storage of software upgrades; and interfaces for out-of-band management access.

Power Supplies:

Each Juniper Routers has one, two, or four load-sharing power supplies. The power supplies are connected to the router midplane (on an M40 router, to the router backplane), which distributes the different output voltages throughout the router and its components. Some routers can operate using either AC or DC power while the other routers operate with DC power only.

Cooling System:

The cooling system keeps all router components within the recommended operating temperature limits. If one component of the cooling system fails or is removed, the system automatically adjusts the speed of the remaining components to keep the temperature within the acceptable range. The cooling system for each router is unique and can consist of fans, impellers, and air filters


3. Router Architecture for M-series Routers and T-series Platforms:

The router architecture separates routing and control functions from packet forwarding operations, which results in increase in the performance of the router.

Each router consists of two major architectural components:

  • The Routing Engine, which provides Layer-3 routing services and network management.

  • The Packet Forwarding Engine, which provides all operations required for transit packet forwarding.

Figure 1: Simplified Router Architecture:

The routing engine constructs one or more routing tables, from these routing tables routing engine generates a table of active routes called forwarding table, this table is then copied into packet forwarding engine.

Routing Engine is the logical location to store the JUNOS software. The Routing Engine operates all routing protocols and makes all routing table decisions, herby building a master routing table with the best path to each destination. The router then places these best paths into the forwarding table on the Routing Engine and copies that same data into the forwarding table on the Packet Forwarding Engine.

4. Features:

The important features of M-Series and T-Series routers include the following:

a. IPv4 and IPv6 unicast and multicast support

b. Routing: Supports IS-IS, RIP ng, BGP, OSPF v3, and Static

c. IP/MPLS routing

d. L2 VPNs, L3 VPNs

e. Supports ICMP v6

f. Offers CLI, and JUNIScript API

g. The routers support a variety of high-speed interfaces (including SONET/SDH, Ethernet, and ATM) for large networks and network applications.

h. High Availablility Options such as Graceful RE Switchover (GRES), and Bidirectional Forwarding Detection (BFD).


JUNOS logical-router

Hmm… interesting:

esigpri@SRLAB1# help topic logical-routers overview
OverviewLogical routers perform a subset of the actions of a physical router and
have their own unique routing tables, interfaces, policies, and routing
instances. A set of logical routers within a single router can handle the
functions previously performed by several small routers.The following are supported on logical routers:
* Open Shortest Path First (OSPF), Intermediate System-to-Intermediate
System (IS-IS), Routing Information Protocol (RIP), RIP next
generation (RIPng), Border Gateway Protocol (BGP), Resource
Reservation Protocol (RSVP), Label Distribution Protocol (LDP), static
routes, various multicast protocols, and Internet Protocol version 4
(IPv4) and version 6 (IPv6) are supported at the [edit logical-routers
protocols] hierarchy level.

* Basic Multiprotocol Label Switching (MPLS) for core provider router
functionality is supported at the [edit logical-routers protocols
mpls] hierarchy level.

* All policy-related statements available at the [edit policy-options]
hierarchy level are supported at the [edit logical-routers
policy-options] hierarchy level.

* Most routing options statements available at the [edit
routing-options] hierarchy level are supported at the [edit
logical-routers routing-options] hierarchy level. Only the
route-record statement is not supported at the [edit logical-routers
routing-options] hierarchy level.

* You can assign most interface types to a logical router, including
SONET interfaces, Ethernet interfaces, Asynchronous Transfer Mode
(ATM) interfaces, ATM2 interfaces, Channelized Q Performance Processor
(QPP) interfaces, aggregated interfaces, link services interfaces, and
multilink services interfaces.

* Source class usage, destination class usage, unicast reverse path
forwarding, class of service, firewall filters, class-based
forwarding, and policy-based accounting work with logical routers when
you configure these features on the physical router.

* Multicast protocols, such as Protocol Independent Multicast (PIM) and
Distance Vector Multicast Routing Protocol (DVMRP) are supported at
the [edit logical-routers logical-router-name protocols] hierarchy

The following restrictions apply to logical routers:
* You can configure a maximum of 15 logical routers on one physical

* The router has only one configuration file, which contains
configuration information for the physical router and all associated
logical routers. Master users can access the full configuration.
However, logical router users can access only the portion of the
configuration related to their particular logical router.

* All configuration commits performed by a logical router user are
treated as commit private. For more information on the commit private
command, see the JUNOS System Basics Configuration Guide.

* If a logical router experiences an interruption of its routing
protocol process (rpd), the core dump output is saved in a file in the
following location:
/var/tmp/rpd_logical-router-name.core-tarball.number.tgz. Likewise, if
you issue the restart routing command in a logical router, only the
routing protocol process (rpd) for the logical router is restarted.

* If you configure trace options for a logical router, the output log
file is stored in the following location:

* The following Physical Interface Cards (PICs) are not supported with
logical routers: Adaptive Services PIC, ES PIC, Monitoring Services
PIC, and Monitoring Services II PIC.

* Graceful Routing Engine switchover, sampling, port mirroring, IP
Security (IPSec), and Generalized MPLS (GMPLS) are not supported.

* Rendezvous point functionality for multicast protocols within a
logical router is not supported.

* Label-switched path (LSP) ping and traceroute for autonomous system
(AS) number lookup are not supported.

Logical Routers and Virtual Routers

A virtual router is not the same as a logical router. A virtual router is
a type of simplified routing instance that has a single routing table. A
logical router is a partition of a physical router and can contain
multiple routing instances and routing tables. For example, a logical
router can contain multiple virtual router routing instances.


esigpri@SRLAB1# help reference logical-routers logical-routers

logical-routers logical-router-name;

Hierarchy Level


Release Information

Statement introduced before JUNOS Release 7.4.


Configure a logical router.


logical-router-name–Name of the logical router.

Usage Guidelines

See “Logical Router Configuration Guidelines”.

Required Privilege Level

routing–To view this statement in the configuration.
routing-control–To add this statement to the configuration.