The Junos OS

The core of Juniper devices is the Junos OS. Junos OS is based on the FreeBSD UNIX operating system (OS). The OS implements a single software train through the entire line of Junos products. The same train is used from the entry-level J series routers to the service provider TX Matrix switches.

To create stable devices that can deliver high performance you need to adhere to sound logic and strict processes. Juniper has done this by keeping a clean separation between the control and forwarding planes on their devices. The control plane includes the routing engine and forwarding table. The forwarding table is linked to the packet-forwarding engine of the forwarding plane, allowing for stable control protocols and high speed forwarding capabilities. The forwarding plane is responsible for the other functions like policing, stateless firewall filtering, and class of service. Transit traffic is forwarded via the Packet Forwarding Engine without passing through the control plane. This is possible because the control plane updates the forwarding table for the forwarding plane. The exception traffic, traffic destined to the local device, is sent to the routing engine CPU.

Configuring Junos Devices

UNIX BSD Shell

Junos has the capability for a user to automatically login to the UNIX BSD shell just like you would normally with a Linux or UNIX device. For example, if you login as root, you will be placed into the UNIX BSD shell. You can’t perform any switching, routing, or security functions from the BSD shell. You must switch to operation mode where you can display statistics and configuration information. The UNIX BSD shell is designated with the % prompt. Here you can enter standard UNIX commands.

root@%

Operational Mode

You can enter operation mode by typing cli and pressing enter. Operational mode is designated with the > prompt. Once you’re in operation mode, you can utilize operational commands, and you can enter configuration mode from here.

root@%
cli root>

Configuration Mode

Entering configure or edit at the operational prompt will place you in configuration mode. Configuration mode is designated with the # prompt. You will also notice that the word edit appears above the prompt in brackets. This shows your level in the command hierarchy and it will change as you change levels.

root> configure
Entering configuration mode
[edit]
root#

Once you enter configuration mode, you are placed at the at the most global and least specific section of the configuration. You can now move directly to the section of the configuration that you would like to configure. For example, if you typed edit interfaces, you would move to the interface level. Once you’re at the interface level and you display the configuration, you will only see interface-level information. This is a nice feature when you have a large configuration, and you only wish to configure a specific part of the configuration.

You do have the option to display the configuration in Junos the same way that you displayed it in Netscreen Screen OS. This is accomplished with the show configuration command with the pipe option and the display set option.

show configuration | display set

Saving Configurations

You use the commit command to save a configuration to the Juniper device. If you make a mistake with a configuration and you save the configuration, you can use the rollback command to use a previous configuration. Actually, you can choose to use one of the last 50 saved configurations.

Monitoring, Maintaining and Troubleshooting Junos Devices

Monitoring

You have many commands in operational mode to display statistics about the Junos device. And, as with most vendors, you can send SNMP traps and SYSLOG messages to a server. Since the Junos device is a UNIX device you will also have access to all of the standard UNIX log files, and the log files are still available after a reboot since they are not stored in RAM.

Maintaining

One thing to keep in mind is that the Junos devices are not like a traditional router since they are based on a UNIX platform. The devices have directory and file structures just like a UNIX server, and it should be treated with care. You should follow the proper procedures when you want to shutdown a Junos device.

Troubleshooting

For troubleshooting you have a couple of options. Junos has the traceoptions function which is the equivalent of other vendors debug function. The traceoptions function is controlled by the traceoptions command. If someone is performing a trace, they are performing the same function as a debug. You can trace many protocols on the Junos devices. The traceoptions function will create a file on the local device. You can view the trace file with the show log command. There is also the monitor function. The monitor function will allow you to monitor in the log files on the Junos device in real-time. It is the equivalent of the tail –f command on UNIX devices. The monitor command used to control the monitor function. The Junos device writes many log files. This is much different than most vendors.

There are many exciting features in the Junos OS. As I mentioned you have direct access to UNIX shell. This comes in handy when you’re troubleshooting with the Junos devices. And you should feel at ease to know that there is a single OS train for all of the Juniper products. Also, take advantage of the help command. You will come up to speed quicker since it’s like having the manual at your finger tips.

Related Course
Junos Foundations: JNCIA-Junos Boot Camp (IJOS, JRE)

Excerpted from Global Knowledge White Paper: Introduction to Junos by Brad Wilson

Challenges

Ottawa Regional’s campus spans eight buildings, which are interconnected with a private fiber network. A physician office is connected to the main campus through T-1 circuits.

The hospital wanted to upgrade its 100 Mbps campus network to 10GbE. It also wanted to enhance network reliability and availability to meet the rigorous demands of healthcare IT, while minimizing complexity and reducing operating expenses. It was time for a new approach and “the new network.”

Ottawa Regional’s new campus network had to meet several requirements. First and foremost, it needed a high-performance infrastructure to support voice over IP (VoIP) and new healthcare information management software. Higher WAN speeds were also essential to support its enterprise virtual private network (VPN), remote access, and a quality voice experience.

The hospital also wanted to improve network resiliency. Its Ethernet switches were daisychained on the fiber, which meant that if one switch failed, the entire network could go down. Plus, the incumbent switches didn’t support Power over Ethernet (PoE), which the hospital needed to support IP telephony. Furthermore, the campus WAN architecture had a single point of failure that could negatively impact the hospital’s enterprise VPN, firewall, and WAN services.

Solution

The hospital deployed Juniper Networks routing, switching, and security solutions to build its new network and also installed new single-mode fiber between campus buildings to support high-performance networking. The campus network consists of Juniper Networks® EX Series Ethernet Switches. The EX4200 line of Ethernet switches with Virtual Chassis technology provides carrier-class performance in a single rack unit form factor that is easy to deploy and manage. The EX4200 switches are also powered by Juniper Networks Junos® operating system.

Virtual Chassis technology enables up to 10 interconnected EX4200 switches to behave and operate like a single logical device, reducing management overhead and operational expenses. Switches can be added to a Virtual Chassis configuration incrementally, as needed, delivering a scalable and energy efficient solution that doesn’t demand a large up-front investment.

Ottawa Hospital deployed Juniper Networks J Series Services Routers at the network edge. The J6350 Services Router is a modular router that’s ideal for enterprises running desktops, servers, VoIP, and enterprise applications. The Juniper routers connect the hospital to the high-speed Illinois Century Network (ICN) as well as AT&T for redundant WAN connectivity.

Juniper Networks SRX Series Services Gateways provide firewall, VPN, and intrusion prevention system (IPS) as well as antispam, antivirus, and Web filtering, protecting the hospital against known and emerging threats. Physicians and administrative staff at Ottawa Regional have secure remote access to key applications via any standard Web browser, thanks to Juniper Networks SA4500 SSL VPN Appliance. The use of SSL eliminates the need for preinstalled client software, changes to internal servers, and costly ongoing maintenance and desktop support. The SA Series provides Ottawa’s IT staff with extranet features that allow controlled access to differentiated users and groups without requiring infrastructure changes, demilitarized zone (DMZ) deployments, or software agents.

Results

One of Ottawa Regional Hospital’s biggest benefits from its new network is the ability to do more with less. With the new network the hospital increased network capacity more than 20 times from its previous infrastructure. The hospital has 10GbE links per fiber strand, which is enabled by a full 20GbE fiber ring to improve network resiliency. With J Series routers, the hospital has successfully migrated from a static routed environment to OSPF, which has improved network resiliency.

The EX Series switches gave the hospital the port density it needed to support core and edge access. It has 48 1GbE PoE ports in a compact platform on the EX Series switches. The routing infrastructure has sufficient room to grow as well, moving from supporting just one T1 to three T1s for redundancy.

Junos OS, a single network operating system that runs across Juniper Networks routing, switching, and security platforms, reduces cost and complexity, minimizes operator error, and increases reliability. Because Junos OS automates network operations in a streamlined system, Ottawa’s IT staff has more time to focus on strategic, proactive efforts.

The hospital has also been able to improve security to better comply with regulatory requirements such as the Health Information Portability and Accountability Act (HIPAA). The hospital now enjoys best-in-class enterprise network compliance security while protecting against emerging security threats. Plus, physicians and staff have secure and easy access to essential applications from anywhere, anytime, which allows the hospital to deliver better patient care.

Excerpted and reposted with permission from Juniper.net (pdf).