Introduction to the Junos Operating System Chapter 2: Junos Operating System Fundamentals 2012 Juniper Networks, Inc. All rights reserved. www.juniper.net Worldwide Education Services
Chapter Objectives After successfully completing this chapter, you will be able to: Describe the Junos operating system and its basic design architecture Explain traffic processing for transit and exception traffic Identify and provide a brief overview of Junos devices www.juniper.net 2-2
Agenda: Junos Operating System Fundamentals The Junos OS Traffic Processing Overview of Junos Devices www.juniper.net 2-3
The Junos OS Robust, modular operating system Provides industry-leading performance and scalability Based on the FreeBSD UNIX operating system www.juniper.net 2-4
Single Software Train A single software train for all platforms running the Junos OS Eases management overhead by providing a consistent set of features that are implemented in a consistent manner 12.0 12.1 J2320 TX Matrix www.juniper.net 2-5
Separation of Control and Forwarding All platforms running the Junos OS share a common design goal: Clean separation of control and forwarding functions Routing Engine RT FT The Junos OS Control Plane Internal Link Forwarding Plane Frames/Packets In FT Packet Forwarding Engine Frames/Packets Out www.juniper.net 2-6
Routing Engine Maintains routing and forwarding tables Controls and monitors the chassis Manages the PFE RT Routing Engine FT The Junos OS Control Plane Forwarding Plane Packet Forwarding Engine www.juniper.net 2-8
Packet Forwarding Engine Uses Layer 2 and Layer 3 forwarding tables, provided by the RE, to forward traffic toward its destination Implements various services such as policing, stateless firewall filtering, and class of service Frames/Packets In Control Plane Forwarding Plane Routing Engine FT Packet Forwarding Engine Frames/Packets Out www.juniper.net 2-9
Agenda: Junos Operating System Fundamentals The Junos OS Traffic Processing Overview of Junos Devices www.juniper.net 2-10
Transit Traffic Processing Transit traffic is forwarded through the local system PFE uses the forwarding table provided by the RE Examples of transit traffic include unicast and multicast traffic Control Plane Forwarding Plane Routing Engine CPU FT Frames/Packets In Packet Forwarding Engine Frames/Packets Out www.juniper.net 2-11
Exception Traffic Processing (1 of 2) Exception traffic is processed by the local system Traffic destined for the local system is processed by RE CPU In most cases, the PFE processes traffic requiring the generation of ICMP messages, such as TTL expired Control Plane Forwarding Plane Routing Engine CPU Frames/Packets In Frames/Packets Out Packet Forwarding Engine www.juniper.net 2-12
Exception Traffic Processing (2 of 2) Exception traffic is rate-limited on the internal link to protect the RE from potential DoS attacks Control traffic is given preference when congestion exists Routing Engine Control Plane CPU Forwarding Plane Built-In Rate Limiting Frames/Packets In Packet Forwarding Engine www.juniper.net 2-13
Agenda: Junos Operating System Fundamentals The Junos OS Traffic Processing Overview of Junos Devices www.juniper.net 2-14
Overview of Junos Devices Platforms running the Junos OS span switching, routing, and security roles and are suited for small to large networks in both enterprise and service provider environments Routing Switching Security www.juniper.net 2-15
Junos Routing Devices ACX Series LN Series M Series MX Series PTX Series T Series www.juniper.net 2-16
Junos Switching Devices EX Series QFX Series www.juniper.net 2-18
Junos Security Devices J Series SRX Series www.juniper.net 2-19
Summary In this chapter, we: Described the Junos OS and its basic design architecture Explained how transit and exception traffic is processed Identified and provided a brief overview of Junos devices www.juniper.net 2-20
Review Questions 1. What are some advantages of the Junos OS? 2. What are the primary functions of the control plane and the forwarding plane on Junos devices? 3. How are transit and exception traffic processed? 4. Name three platforms that run the Junos OS. www.juniper.net 2-21
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