3troubleshootingjunos
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Troubleshooting JUNOS Platforms
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Power On, Pow Off, and Boot Media |
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JUNOS Platforms Hardware Troubleshooting • Chapter 4–5
Troubleshooting JUNOS Platforms
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dist ibuti n panels,Reproductionone of which might be located at the top of the rack where |
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Powering On JUNOS Platforms |
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Each device can be quipp with two redundant, load-sharing power supplies of the |
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same type, either AC or DC. Be sure to connect each power source properly. For |
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example, each power supply requires a dedicated power source. For sites with an AC |
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power sou ce, each power supply has one power cord, which plugs into a grounded |
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100–240 VAC power receptacle. For sites with a DC power source, power is normally |
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car ied a ound the site through a main conduit to frame-mounted DC power |
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intend to install the device. A pair of cables (–48 V and RTN) connects each DC supply |
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to the p |
wer distribution panel. Grounding studs are provided at the rear enclosure. |
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nnecting all cables, turn one power supply on first and then the second supply |
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avoid a large power spike.
Although the specifics of each power supply and Power Entry Module (PEM) vary by platform, note that after a power supply is powered on, it can take up to 60 seconds for status indicators—such as LEDs on the power supply and show chassis commands—to indicate that the power supply is functioning normally. You should ignore error indicators that appear during the first 60 seconds.
Continued on next page.
Chapter 4–6 • JUNOS Platforms Hardware Troubleshooting
Troubleshooting JUNOS Platforms
Powering Off JUNOS Platforms
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If you want to power off a device, we recommend that you do a graceful shutdown as |
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opposed to simply removing power from the system. A graceful shutdown initiates |
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when you issue a request system halt command. Once the system properly |
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halts, you can safely turn off the power supplies. Note that file system corruption can |
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occur if you remove power before executing a graceful shutdown because of the |
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multitasking nature of JUNOS Software. |
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JUNOS Platforms Hardware Troubleshooting • Chapter 4–7
Troubleshooting JUNOS Platforms
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Hardware Controls the Boot S quence |
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At power on, as the |
vice b gins the boot process, it first attempts to start the image |
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of software from the r |
movable m dia if it is installed in the Routing Engine. If this |
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attempt fails or if no media is present, the device next tries to boot from the image of |
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softwa e on the flash disk and then finally from the hard disk. |
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This sequence is controlled by hardware that waits for a special signal from the JUNOS S ftwa e ke nel, indicating a successful boot. If the hardware does not receive the signal after a few minutes, it forces the system to boot from the next available device in the b t chain.
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Chapter 4–8 • JUNOS Platforms Hardware Troubleshooting
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Troubleshooting JUNOS Platforms
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•ReproductionFlash disk (nonrotating disk): Some JUNOS platforms ship with |
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JUNOS |
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Three Forms of Boot and Storage Media |
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JUNOS platforms g rally support three forms of boot and storage media: |
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emovable media: Depending on the platform model, your device might |
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have a PC card slot (which reads flash disks), a compact-flash slot, or a |
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universal serial bus (USB) port. A copy of JUNOS Software on removable |
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media ships with most JUNOS platforms. |
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Software preinstalled on the flash disk. For example, the flash disk is the |
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primary boot device for M Series and T Series platforms. |
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Hard disk (rotating disk): Some JUNOS platforms have a backup copy of |
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JUNOS Software preinstalled on the hard disk. This disk also stores |
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system log files and diagnostic dump files. |
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A JUNOS platform typically boots either from the flash disk or from the hard disk. (While it is possible to boot the device from the removable media disk, you typically do not do so.) We refer to these disks as the boot media. The disk from which the device boots is named the primary boot medium, and other disks are secondary boot media. Depending on the platform, the primary boot medium is generally the flash disk, and the secondary boot medium is generally the hard disk.
Continued on next page.
JUNOS Platforms Hardware Troubleshooting • Chapter 4–9
Troubleshooting JUNOS Platforms
CLI Option to Control Boot Media at the Next Reboot
The slide illustrates the choices that you could make when selecting from which media to boot for two types of platforms—the M10i and the SRX210. When issuing a request system reboot command, you can flag which boot medium should be used next by including the media switch. Note that this flag is temporary and affects only the next reboot.
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Chapter 4–10 • JUNOS Platforms Hardware Troubleshooting
Troubleshooting JUNOS Platforms
ChooseReproductionthe Boot D vice at Boot Time
At times you might want to manually choose to boot from alternative media even though the flash file syst m is bootable. You can tell the system to boot from a given medium to override its desire to always boot from flash disk.
forTo select an alternative medium at the time of boot, watch for the boot loader screen shown on the slide. When prompted, enter a space to access the boot loader command prompt. From the prompt you can get some help with the ? key. As indicated in the initial help screen, typing reboot causes the device to reboot from the next device on the boot list. This device should be the hard disk because the flash disk is normally the first boot device. When needed, you can manually select the device to use when the reboot command executes by first using the nextboot command with the desired medium type specified as an argument.
The p efe red way to force a boot from the hard disk is to issue a request system eboot CLI command with the media switch and disk argument. You can also
select a boot device during the actual boot process when yo connect through the
c ns le. This technique is useful if you are unable to access the CLI, perhaps because a software fault in the flash file system (a fault that leaves the flash medium
b table but unusable from a JUNOS Software CLI perspective). Not
JUNOS Platforms Hardware Troubleshooting • Chapter 4–11
Troubleshooting JUNOS Platforms
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As supported JUNOS platforms boot, the current status of the boot process displays on the Craft Interface LCD.
Craft InterfaceReproductionLiquid Crystal Dis lay
forCraft Inte face LEDs
A se ies f diagnostic tests are performed the Flexible PIC Concentrators (FPC) du ing the b t p ocess. Blinking LEDs indicate tests in progress. They become solid
a ter c nclusi n of the testing period. Depending upon the platform, the Craft
Inter ace might also support LEDs for host module (Routing Engine and Control Board combination) Switch Interface Board (SIB) status.
Alarm LEDs Illuminate as Needed
Should any red or yellow alarms arise, the corresponding alarm LED illuminates on the Craft Interface. To see the specifics relating to a given alarm, you can look at the LCD on the Craft Interface (when present) or use the command show chassis alarms.
Chapter 4–12 • JUNOS Platforms Hardware Troubleshooting
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Troubleshooting JUNOS Platforms
PowerReproductionSupply and Pow r Entry Module LEDs
Depending upon the platform and power supply model, one or more status LEDs on each power supply or Pow Entry Module (PEM) might exist that you can use to determine if a power supply is functioning normally. Note that for some platforms you must wait at least 60 seconds after applying power to a power supply before you can
forexpect to see meaningful status indications. The self-test button present on some power supplies should never be used on a production system; this button is for enginee ing and Juniper Networks Technical Assistance Center (JTAC) use only.
JUNOS Platforms Hardware Troubleshooting • Chapter 4–13
Troubleshooting JUNOS Platforms
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Using the CLI to Troubl shoot |
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The slide highlights the topic we discuss next. |
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Chapter 4–14 • JUNOS Platforms Hardware Troubleshooting