THAI CPE

• An exception packet could be a routing protocol update, a locally addressed packet, or a packet requiring the generation of an ICMP error message. The CPU on the router's control board handles these exception packets and performs the appropriate action.
  
  
• 
  
  
• Operates routing protocols, loads the JUNOS software, and controls the CLI are the functions of the Routing Engine.
  The Routing Engine performs multiple functions, including operating the routing protocols on the router, loading the JUNOS software, and controlling the CLI. The Packet Forwarding Engine controls packet forwarding.
  
  
• Routing Engine router component is responsible for creating the forwarding table.
  The Routing Engine builds the master routing table, selects the best path to each route, and places those next hops into the forwarding table.
  
  
• The PIC I/O Manager ASIC is responsible for transmitting packets function.
  The PIC I/O Manager ASIC is responsible for receiving and transmitting data packets from the physical media connected to the PIC.
  
  
• The Internet Processor ASIC is responsible for performing route lookups function.
  The Internet Processor ASIC consults the forwarding table on the control board to determine the next-hop router along the path to the destination.
  
  
• The I/O Manager ASIC is responsible for creating J-cells function.
  The I/O manager ASIC is responsible for multiple functions in the router. One of those is the creation of J-cells from the original data packet.
  
  
• The Distributed Buffer Manager ASIC is responsible for storing packets in memory function.
  The primary role of the Distributed Buffer Manager ASIC is storing and retrieving J-cells from the packet storage buffer.
  
  
• A unicast packet is flowing through the Packet Forwarding Engine. Incoming I/O Manager ASIC receives the packet after the incoming PIC I/O Manager ASIC performs its functions.
  After receiving the packet from the physical media and performing any link-layer functions, the incoming PIC I/O Manager ASIC sends the packet to the incoming I/O Manager ASIC on its FPC.
  
  
• Switching control board CPU component of the router is responsible for handling exception packets.
  The CPU on the router's control board is responsible for handing exception packets. Some of those exception packets might reach the Routing Engine.
  
  
• IP packets with TTL=1 and Routing protocol updates are considered exception packets.
  Routing protocol updates and packets requiring an ICMP error message (TTL=1) are considered exception packets. A Juniper Networks router does not communicate using the HTTP or SMTP protocols. Therefore, these packets must be transiting the router and are handled by the Packet Forwarding Engine.
  
  
• mgd JUNOS software daemon is responsible for operating the CLI.
  The Management Daemon (mgd) is responsible for controlling the CLI process.
  
  
• rpd JUNOS software daemon is responsible for controlling the routing protocols.
  The Routing Protocol Daemon (rpd) is responsible for all routing protocol activity on the router.
  
  
• When issued from the top of the configuration hierarchy, save saved-file command creates a file called saved-file that contains the entire candidate configuration.
  The save command takes portions of the candidate configuration and places them in a file you specify. When used from the top of the hierarchy, this process saves the entire candidate configuration.
  
  
• rollback 5 command places the juniper.conf.5.gz file in the candidate configuration.
  load override juniper.conf.5.gz and load merge juniper.conf.5.gz will look for the juniper.conf.5.gz file in the user's home directory, where it is not stored by default.
  
  
• /var/home is the router store each user's home directory.
  Each user configured on the router receives his or her own home directory in the /var/home section of the hard drive.
  
  
• Internal flash drive is the primary boot media for the JUNOS software.
  The router's internal flash drive is the primary boot location for the JUNOS software.
  
  
• Internal hard drive is the secondary boot media for the JUNOS software.
  The router's internal hard drive is the secondary boot location for the JUNOS software.
  
  
• request system software add filename command loads a new version of the JUNOS software into the internal flash drive.
  The request system software add filename command loads a copy of the JUNOS software onto the router's flash drive.
  
  
• Ctrl+A Emacs keystroke takes the cursor to the beginning of the command line.
  To reach the beginning of the command line, use the Ctrl+A keystroke. Ctrl+E takes you to the end and Ctrl+W deletes the previous word. Ctrl+D closes your terminal during a load merge terminal operation.
  
  
• load merge terminal command allows you to paste text directly into the candidate configuration.
  The load merge terminal command allows you to cut and paste configuration directly into the router.
  
  
• When committing configuration, commit confirmed command allows the router to automatically return to a previous configuration.
  The commit confirmed command allows the router to return to the previous configuration automatically if don't issue a regular commit within the default 10-minute timer.
  
  
• 
  
  
• The format consists of a two-character media type designator followed by the FPC slot number, the PIC slot number within an FPC, the port number on the PIC, and the logical unit. the format is media_type-fpc/pic/port.unit.
  
  
• Each Juniper Networks router contains the fxp0 and fxp1 permanent interfaces. All interfaces contained on a PIC are considered transient because they can be removed at any time.
  
  
• The inet, inet6, iso, and mpls protocol families are configurable on a Juniper Networks interface.
  
  
• Each interface in the JUNOS software requires some logical properties. These often include the Layer 3 and Layer 2 addressing information for enabling proper network operation.
  
  
• The show interfaces extensive command, information such as the current status, input/output byte and packet statistics, and input/output error counters are available in the command output.
  
  
• Both loopback and BERT testing help to locate trouble spots on a physical network circuit.
  
  
• 
  
  
• Type, FPC, PIC, and port is the order of elements in the JUNOS software interface naming convention.
  The order is the media type, FPC slot number, PIC slot number, and PIC port number.
  
  
• 0 through 7, left to right are the FPC slot numbers for an M40e numbered.
  An M40e has eight vertical FPC slots. They are numbered 0 through 7, left to right.
  
  
• 0 through 3, right to left are the PIC slots numbered on an M20 FPC.
  An M20 has four PIC slots in each FPC. Since the FPC has a horizontal orientation, the PIC slots are numbered 0 through 3, right to left.
  
  
• Permanent and transient are two different types of interfaces on a Juniper Networks router.
  Juniper Networks routers have two types of interfaces: permanent and transient.
  
  
• Keepalives, Description, and FCS are the example of a physical interface configuration.
  Only the protocol address is a logical property of an interface.

• OSPF hello packets that are sent from a remote router and are destined for the local router and Telnet traffic that is sent from a remote host and is destined for the local router are two examples of RE exception traffic.
  
  
• A BGP router only uses the MED attribute, by default, when multiple routes in the Adjacency-RIB-In table have arrived from the same neighbouring AS.
  
  
• By default, a Response message carries 25 route entries. When plain-text authentication is configured, one route entry is used to store the authentication data. Therefore, only 24 route entries can be advertised in this scenario. Using MD5 authentication, however, requires the use of two route entries, leaving a capacity of 23 RIP routes in the message.
  
  
• ge-4/3/2:
  
  • media type Gigabit Ethernet interface in slot 4 in the chassis/slot 3 of the FPC/port 2 in a PIC.
  • media type Gigabit Ethernet interface on FPC 4/PIC 3/Port 2.
    
    

• RIPv2 defaults to advertising Response messages using the 224.0.0.9/32 multicast group address.
  
  

• Using an MPLS network to support Layer 3 VPNs.By default, the JUNOS software stores VPN routing information advertised between Provider Edge routers in the bgp.l3vpn.0 routing table.
  
  

• The JUNOS software places a single next-hop entry into the forwarding table for each valid route in the routing table, by default. Can modify this behaviour by configuring a routing policy within the [edit routing-options forwarding-table] configuration hierarchy.
  
  

• 3 prefixes will match route-filter 192.168.0.0/16 upto /17. The upto match type stops the evaluation of the route filter and matches the routes found at the specified level. This route filter matches the 192.168.0.0/16, 192.168.0.0/17, and 192.168.128.0/17 routes.
  
  

• The Routing Protocol Daemon (rpd) software process is responsible for / in charge of operating all routing protocols in the JUNOS software.
  
  

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Certification Levels:

• Up to four levels per track:
  
  • JNCIA - Internet Associate
    
    • Multiple choice exam
  • JNCIS - Internet Specialist
    
    • Multiple choice exam
  • JNCIP - Internet Professional
    
    • Multiple choice exam
  • JNCIE - Internet Expert
    
    • One-day, lab-based exam
      

Introduction to JUNOS Software:

JUNOS Software:

• Robust, modular operating system
  
  • Provides industry-leading performance and scalability
  • Based on the FreeBSD UNIX operating system
    
    
• Protocols
• Interface Mgmt
• Chassis Mgmt
• SNMP
• Security Services
• ...
  

Single Software Train:

• A single software train for all platforms running JUNOS Software
  
  • Eases management overhead by providing a consistent set of features that are implemented in a consistent manner
    

Separation of Control and Forwarding:

• All platforms running JUNOS Software share a common design goal:
  
  • Clean separation of control and forwarding functions
• Control Plane: Routing Engine (RE)
  JUNOS Software: Routing Table (RT) > Forwarding Table (FT) - Internal Link >
• Forwarding Plane: Packet Forwarding Engine (PFE)
  Frames/Packets In > FT > Frames/Packets Out
  
• MAC Table = Bridge Table

Routing Engine:

• Maintains routing and forwarding table

Packet Forwarding Engine (PFE):

• Uses Layer 2 and 3 forwarding
  
• ACL = stateless firewall filtering

Transit Traffic Progressing: Pass-through

Exception Traffic Processing:

• Exception traffic is rate-limited

Overview of JUNOS Platforms:

• M Series
• T Series: Core Router
• SRX Series: Firewall

Common User Interface Options:

• JUNOS CLI:
  
  • Text-based command shell
  • Accessible through the console port using a terminal emulation program
    
    • Uses RJ-45 RS-232 @ 9600 Bps, 8/1/N (not configurable)
  • Also accessible through network ports using an access management protocol such as Telnet or SSH
    
    • Requires network interface and related service configuration
    • Many Junos devices include a dedicated management Ethernet interface used for out-of-band access
• J-Web:
  
  • Web-based graphical user interface
  • Accessible through an HTTP-enabled or HTTPS-enabled browser
    

Logging In:

• When logging in:
  
  • Nonroot users are placed into the CLI automatically
    login: user
    Password:
    user@host> - CLI Prompt
    
  • The root user must start the CLI from the shell
    
    • Remember to exit the root shell after logging out of the CLI!

    root@router% cli - Shell Prompt
    

CLI Modes:

• Operational mode:
  
  • Monitor and troubleshoot the software, network connectivity, and hardware
    user@router> - The > character identifies operational mode
• Configuration mode:
  
  • Configure the device, including interfaces, protocols, user access, and system hardware properties
    [edit]
    user@router# - The # character identifies configuration mode
    

Context-Sensitive Help:

• Type ? anywhere on the command line to get help:
  user@router> ?
  Possible completions:
    clear                Clear information in the system
    configure            Manipulate software configuration information
    file                 Perform file operations
    help                 Provide help information
    ...
  
  user@router> clear ?
  Possible completions:
    amt                  Clear AMT Protocol information
    arp                  Clear address resolution information
    auto-configuration   Clear auto-configuration action
    bfd                  Clear Bidirectional Forwarding Detection information
    ...
  

JNCIA:

Command and Variable Completion:

• Use the Spacebar to complete commands:
  user@host> sh<space>ow i<space>
  'i' is ambiguous.
  Possible completions:
    iccp                 Show Inter Chassis Control Protocol information
    igmp                 Show Internet Group Management Protocol information
    ike                  Show Internet Key Exchange information
    interfaces           Show interface information
    ipsec                Show IP Security information
    ipv6                 Show IP version 6 information
    isis                 Show Intermediate System-to-Intermediate System information
  
  
• Use the Tab key to complete commands and variables:
  [edit policy-options]
  user@router# show policy-statement t<tab>his-is-my-policy
  then accept;
  

Editing Command Lines:

EMACS-style editing sequences are supported:

• Ctrl+b(ackward): Moves the cursor left one character;
  
• Ctrl+a: Moves the cursor to the beginning of the command line;
• Ctrl+f(orward): Moves the cursor right one character;
• Ctrl+e(nd): Moves the cursor to the end of the command line;

A VT100 terminal type also supports the Arrow keys

Using | (Pipe):

• Use | (pipe) to filter and manipulate command output:
  user@host> show route | ?

CLI Operational Mode:

• Execute operational mode commands to monitor and control the operation of devices running the Junos OS
  
  • Hierarchy of commands: Less Specific > More Specific
    
    • Example: user@host> show ospf interfaces

Active Versus Candidate Configuration:

• Batch configuration model:
  
  • Must commit configuration changes
• Active configuration:
  
  • Current operational configuration
  • Boot-up configuration
• Candidate configuration:
  
  • A working copy for configuration changes
  • Initialized with the active configuration
  • Becomes active configuration upon commit
    

Overview: The Life of a Configuration File:

• Active Configuration 0 - configure > Candidate Configuration - commit > Active Configuration 0
• Active Configuration 0 - rollback 1-49 > Candidate Configuration

Entering Configuration Mode:

• Type configure at the operational mode prompt to enter configuration mode
• Use configure exclusive to:
  
  • exclude other users from editing the configuration
  • allow only a single person to edit a configuration
    
  • Any uncommitted changes are discarded when users exit
  • > configure ?
      exclusive            Obtain exclusive lock (other users cannot make changes)
    
• Use configure private to allow users to edit private copies of candidate configuration concurrently
  
  • When users issue a commit, their private changes merge back into the global configuration
  • Any uncommitted changes are discarded when users exit
  • If two users make competing changes, the first user's commit succeeds, and the second user receives a warning
    
    • The second user must issue a second commit to activate the change
      

Configuration Statement Hierarchy:

[edit]
user@host# edit protocols ospf area 51 stub

[edit protocols ospf area 0.0.0.51 stub]
user@host#

Configuration File Is Hierarchical:

• Enter CLI commands without curly brackets:
  [edit system]
  user@host# set services web-management http port 8080
  
  
• The result is a hierarchical configuration file, complete with curly brackets:
  [edit system]
  user@host# show services
  web-management {
    http {
      port 8080;
    }
  }

Moving Between Levels:

• edit: functions like a change directory command / a CD command:
  user@router# edit protocols ospf area 51
  
• up: moves up one level in the hierarchy
• up n: moves up n levels in the hierarchy
  
• top moves to the top of the hierarchy
• exit moves to the previous, higher level in the hierarchy or exits configuration mode if at the top level of the hierarchy
  

Junos Troubleshooting Process:

Before You Begin...:

• First, do no harm:
  
  • Know what is normal
  • Use change control processes
  • Plan for the worst
  • Backup configurations and other key files
  • Use non-disruptive practices
  • Recreate in a lab environment
  • Use maintenance windows

Know What Is Normal:

• You must know what is normal for your system:
  
  • Establish a baseline before a problem occurs:
    
    • Resource utilization
    • Throughput
    • Types of traffic
• Confirm the symptoms:
  
  • Always verify a problem exists before conducting potentially disruptive testing

Change-Control Processes:

• Use change-control processes:
  
  • Formalized
  • Balance needs with risks
  • Coordinate scheduling to minimize impact to production
  • Remember, customers might have change control policies in place as well

Plan for the Worst:

• Have a back-out plan

Configuration:

• Working with configurations:
  
  • Use save to make backups before modifying a configuration:
    
    • All or part of a configuration can be saved locally or remotely
  • Use commit comment to add comments:
    
    • Logged comments can help when a quick rollback is needed
  • Use commit confirmed to temporarily activate
    
    • When working with remote systems
    • When adding or modifying policies, firewalls, or other security elements

Disruptive Practices:

• Be aware of disruptive practices:
  
  • Review power-on hardware information for your equipment:
    
    • Hot-swappable FRUs
    • Hot-pluggable FRUs
  • Review hardware redundancy options where available
  • Be careful when using hidden CLI commands:
    
    • Hidden commands are hidden for a reason
    • Understand disruptive potential before using
  • Be careful when using disruptive testing techniques

Recreate in Lab Environment:

• Why start a lab reproduction effort?
  
  • You can troubleshoot without affecting customer traffic even when your actions are potentially disruptive
  • You are free to experiment with possible workarounds:
    
    • One possible methodology is to start with a simple setup, and add detail until the problem can be reproduced
  • Lab reproduction is invaluable for some problems:
    
    • Protocol anomalies
    • Interoperability issues
    • Unexpected signaling behavior
  • When is lab reproduction not useful?:
    
    • When a problem is tied to a specific device or circuit failure
    • When the complexity of the network or of the potential triggers makes reproduction unfeasible

Maintenance Windows:

• Minimize impact from unforeseen issues
• Do not be distracted by perceived urgency
• Customers have maintenance windows too

Troubleshooting:

• The ability to identify the root cause of a problem impacting the network
• The ability to identify the root cause of any deviation from the normal or expected behavior of a network

A Process-Based Methodology:

• Learnable
• Repeatable
• Can be used when dealing within any of these elements of a device running the Junos OS:
  
  • Chassis
  • Control plane
  • Interfaces and circuits
  • Data plane

Where To Begin?:

• The scientific method:
  
  • Characterize a problem based on observation and experience
  • Hypothesize and propose an explanation for the observation
  • Make a prediction based on past experiences
  • Test and experiment to prove or disprove the accuracy of the prediction

Troubleshooting Steps:

• Define success
• Isolate the component preventing success:
  
  • Characterize
  • Hypothesize
  • Predict
  • Test and experiment
• Identify a solution
• Implement the solution

Define Success:

• Quantify the problem:
  
  • What is happening that should not be happening?
  • What should be happening that is not happening?
• Define a desirable endpoint:
  
  • Be specific
  • Define a recognizable endpoint
  • Example: prefix a.b.c.d/z will be received from neighbor x
• Be careful not to define success using preconceived solutions

Verify the Problem:

• Once defined, verify the problem exists before proceeding with troubleshooting:
  
  • Troubleshooting can be more disruptive than the problem

Isolate the Problem:

• Isolate the component preventing success:
  
  • Characterize
  • Hypothesize
  • Predict
  • Test and experiment

Characterize the issue:

• Collect information:
  
  • System logs
  • Protocol traceoptions
  • Operational mode command output
• Ask probing questions:
  
  • When did this start happening?
  • Has this ever worked?
  • When did this last work as desired?
  • What has changed?
  • What troubleshooting steps and actions have been tried already?
• Identify the knowns and unknowns

Hypothesize:

• Suggest possible explanations for observed behavior:
  
  • Identify all required components and dependencies
    
    • Use your knowledge of the technology
    • Remember the OSI
    • Use online references
    • When possible, reconstruct a working scenario
  • Be complete
  • Do not assume
  • Do not overlook the obvious

Layered Approach:

TCP - OSI:

• Link - Physical, Data Link
• Internet - Network
• Transport - Transport
• Application - Session, Presentation, Application

Revisiting Control and Data Planes:

• Control Plane - Routing Engine - Common Symptoms: Missing routes
• Data Plane - Ingress > PFE - FT > Egress > Common Symptoms: Physical errors, dropped packets (all or some)
  
  
• Generally a good idea to begin diagnosis at the control plane

Predict and Test:

• Make a prediction:
  
  • Identify most probable explanation
    
    • Be complete
    • Do not assume
    • Do not overlook the obvious
  • Test to prove (or disprove) your hypothesis
    
    • Validity, validity, validity!

Recursive Process:

• "If at first you don't succeed...":
  
  • Divide and conquer:
    
    • Remember the reference models
  • Narrow down the possibilities:
    
    • Validity, validity, validity!
    • Build your own troubleshooting flowchart as you go
    • Each test should reduce the number of possible causes for the problem, regardless of pass/fail status
  • Remember, more than one contributing factor could be present (particularly in new setups)

Consider the Possibilities:

• Possible causes:
  
  • Configuration
  • Hardware
  • Software
  • Something else
• Remember, more than one contributing factor could be present:
  
  • New installations
  • Some troubleshooting has already occurred
  • New, previously unnoticed issues, become apparent

Monitoring Memory and Storage:

• Enter into configuration mode and load the device's reset configuration by issuing the load override jtnoc/lab3-start.config command.
  
  
• Change the root password to lab123 by issuing the set system root-authentication plain-text-password command.
  
  
• Issue the show system storage command to determine the amount of storage space available on your router.
  User home directories are located at /var/home. The /var directory is mounted on a partition of ada1s1f, so it is currently being used to store user home directories.
  
  
• Enter the shell as the root user by issuing the start shell user root command. Enter the password of lab123 when prompted.
  
  
• Perform a read-only test to determine the integrity of the ada1 storage drive. Use the dd if=/dev/ada1 of=/dev/null bs=1m command to perform the test.
  It might take between 5 or 10 minutes for the test to complete. Be patient.
  
  • If the test results show that errors occurred, please notify your support because your router might be experiencing a hardware failure.
  • 4192247808 bytes transferred in 95.412312 secs (43938227 bytes/sec)
    4192247808 bytes were read from the da0 flash drive.

Viewing Boot and System Logs:

• Direct your router to reboot in 20 minutes using the request system reboot in 20 command.
  Shutdown at Tue Jan 16 09:58:54 2018.
  The router will reboot at 09:58.
  
  
• Clear the schedule reboot using the clear system reboot command.
  
  
• Direct your router to reboot immediately using the request system reboot command.
  
  
• View the boot messages that occurred during the reboot process by issuing the show system boot-messages | no-more command.
  The boot messages record the step-by-step process that the RE goes through to boot. No critical errors should have occurred. You may see a few instances while the system is coming online.
  
  
• Use the show system uptime command to determine the router's current time and date.
  Current time: 2018-01-16 09:53:28 ICT
  The time and date are currently 2018-01-16 09:53:28 ICT.
  
  
• View the messages log file using the show log messages to view detailed information about the PFE during the reboot that just occurred. It might be helpful to use the match modifier to ensure that only entries from today's date are shown. For example, if today's date is Jan 16th, issue the command show log messages | match "Jan 16" (you might need to use two spaces between month and day).
  
  
• You might notice that matching on the date might not narrow the search down enough because thousands of entries might happen on any one day. Use the previous command but add a second pipe that matches on reboot, show log messages | match "Jan 16" | match reboot.
  
  • Jan 16 10:12:31.570 2018  vmx1 mgd[95632]: UI_REBOOT_EVENT: System rebooted by 'lab'
    The first reboot was issued at 10:12:31.
  • Jan 16 10:12:31.594 2018  vmx1 shutdown: reboot requested by lab at Tue Jan 16 10:32:31 2018
    This indicates that we requested the reboot to happen 20 minutes later.
  • Jan 16 10:14:44.681 2018  vmx1 mgd[95632]: UI_REBOOT_EVENT: System rebooted by 'lab'
    The second request was issued at 10:14:44.
    
    
• Using the show log messages | match chassisd | match fpc | match online command, determine the exact time that FPC 0 came back online after the reboot. (Status of FPCs are tracked by chassisd.)

Monitoring Chassis Alarms:

• Determine if any alarms exist by issuing the show chassis alarms command.
  2 alarms currently active
  2 active alarms exist.
  
  
• Enter configuration mode and change the default chassis alarm settings such that if any Ethernet ports are in the link-down state issuing set chassis alarm ethernet link-down red, the router will generate a red alarm.
  
  
• delete chassis alarm ethernet link-down

Examining User Processes and Daemons:

• Issue the show system users command.
  USER     TTY      FROM                              LOGIN@  IDLE WHAT
  lab    pts/0    192.168.0.231                    2:23PM      - -cli (cli)   
  
  • Only the user, lab, is logged in to your device.
  • Shows that user lab is logged in from the IP address of 192.168.0.231.
    
    
• Forcibly remove the instance of user by issuing the request system logout user lab terminal pts/0.
  
  
• Issue the show system processes extensive command.
  
  • The chassisd daemon manages the chassis components of the router.
  • The rpd daemon manages the routing function.
    
    
• Issue the show route command.
  
  • 10.85.0.12/32      *[Direct/0] 16w3d 20:52:27
    Shows that the oldest route has been in the routing table for 16w3d 20:52:27.
  • If for some reason the rpd process were to restart, the Junos OS removes all routing information from the routing table. Then, the Junos OS adds any current routing information through independent and dynamic routing protocols.
    
    
• Issue the restart routing command.
  
  • All the routes in the routing table were removed and replaced with new routes, which you can see by viewing the current age of the routes in the routing table.
  • Restarting rpd causes ISIS to completely reconverge. All neighbor adjacencies must re-establish, the router must repopulate the linkstate database, and calculations must run on all possible routes to determine the best path.
  • You can restart only ISIS by deactivate protocols isis command in the [edit] hierarchy level, committing the configuration, activate protocols isis, and committing the configuration again.

Generating Core Files:

• Issue the show system core-dumps command:
  /var/crash/*core*: No such file or directory
  /var/tmp/*core*: No such file or directory
  No core dump files are present on your device.
  
  
• Generate a core dump file using the rpd process, request system core-dump routing.
  
  
• Delete the core dump from the device using the file delete command.

• show interface ge-0/0/4
    Link-level type: Ethernet, MTU: 1514, MRU: 1522, LAN-PHY mode, Speed: 1000mbps, BPDU Error: None, Loop Detect PDU Error: None,
    Logical interface ge-0/0/4.0 (Index 336) (SNMP ifIndex 530)
        Flags: No-neighbor-learn, Sendbcast-pkt-to-re
  
  • The link speed is 1000mbps.
  • The physical MTU is 1514.
  • The default physical MTU is 1514 in Junos.
  • The No-neighbor-learn Flag indicates the interface has been configured to not learn neighbours MAC addresses.
    
    
• Issue the show arp command to review the currently learned MAC addresses.
  
  
• Issue the show interfaces ge-0/0/4 | match hardware command to get the current MAC address on another side.
  
  
• Navigate to the [edit firewall family inet filter filter-1] hierarchy and configure a static ARP entry for the neighbour address (192.168.11.2) with the MAC address identified in the previous step.
  set unit 0 family inet address 192.168.11.1/30 arp 192.168.11.2 mac 52:54:00:99:23:4a

A short IS-IS review:

• Hierarchical link-state protocol
• Can divide a network into areas to increase scalability
• Unlike OSPF, areas are a property of the whole router, not of interfaces
• An interface can belong to two levels (even simultaneously)
  
  • Level 1: Routes traffic within an area
  • Level 2: Routes traffic across areas
• Maintains database synchronization by periodic check on database content
• Very extensible: Built-in support for IPv6, MPLS-TE

IS-IS Terminology and Examples:

• Key IS-IS features and terminology:
  
  • No neighbours but adjacencies
  • No routers but intermediate systems
  • No different LSA types as in OSPF - just a single object, the LSP (link state PDU), with a very complex structure
  • Separate database for Level 1 and Level 2
  • The use of TLV makes it easy to extend
  • Can add support for features like MPLS-TE and IPv6 simply by defining additional TLVs

The IS-IS adjacency state machine:

• Neighbour discovery Bidirectional communication check:
  
  • Down
  • New
  • Two-way
• Link-state database synchronization:
  
  • Initializing
• Initial SPF computation:
  
  • Up
    
    
  • Rejected

Troubleshooting IS-IS:

• Issue the show isis interface command to view the interfaces that have been configured for IS-IS.
  
  
• Issue the show isis adjacency command to view the status of the IS-IS neighbour relationships.
  
  
• Change the perspective of the CLI to that of the R2 logical system by issuing the set cli logical-system R2 command.
  
  
• show route 192.168/16
  show route 2001::/16
  The mxC router's loopback interface route is missing.
  
  
• Examine the link-state database using the show isis database command.
  Link-state PDU seems to be missing.
  
  
• Connect to the missing router, enter configuration mode and navigate to the [edit protocols isis] hierarchy. Enable traceoptions using a file called isis and the flag error detail options.
  set traceoptions file isis
  set traceoptions flag error detail
  
  
• Check the logs generated because of the traceoptions settings by issuing the show log isis command.
  ERROR: Possible sysid collision.
  
  
• Navigate to the [edit interfaces lo0] hierarchy. Issue the show command and review the ISO address on assigned to the loopback interface.
    family iso {
      address 99.0001.0000.0000.7801.00;
  
  
• Fix the incorrectly configured address.
  rename unit 0 family iso address 99.0001.0000.0000.7801.00 to address 49.0001.0000.0000.7105.00
  
  
• Exit from the logical-system:
  clear cli logical-system
  

Troubleshooting BGP:

• Use the show bgp summary command to view the BGP neighborships.
  
  
• Use the show bgp neighbor 172.22.131.37 command to examine the session that is currently in an Active state.
  Peer: 172.22.131.37 AS 65230  Local: 172.22.131.38 AS 65501
    Error: 'Open Message Error' Sent: 6 Recv: 0
  
  
• Enter into configuration mode and navigate to the [edit protocols bgp] hierarchy and enable traceoptions flagging the normal and open conditions.
  set traceoptions file bgp-trace
  set traceoptions flag normal
  set traceoptions flag open
  
  
• Review the contents of the new traceoptions file and identify the problem relating the failure to establish a neighborship with EBGP peer.
  show log bgp-trace
  bgp_process_open:4059: NOTIFICATION sent to 172.22.131.37 (External AS 65230): code 2 (Open Message Error) subcode 2 (bad peer AS number), Reason: peer 172.22.131.37 (External AS 65230) claims 65530, 65230 configured
  The message indicates that 65230 is configured but the peer is looking for 65530.
  
  
• Issue the show configuration protocols bgp command to see group_name. Correct the peer AS number that is not configured correctly for the EBGP group by changing the configured peer AS to 65530.
  set group ebgp-AS65530 peer-as 65530
  

Routing Policy Overview:

• Import and export protocol policies
  
  • The role of policies in the flow of routing information

  Neighbors - Import policy > Routing information base - Export policy > Neighbors
  Routing information base - Best route selection > Forwarding Table
  

• Forwarding table export policy:
  
  Routing information base - Best route selection with Export policy > Forwarding Table
  
  user@router# show routing-options
  autonomous-system 65512;
  forwarding-table {
    export forwarding-policy;
  }
  
  

1. Examples of RE exception traffic:
   
   • OSPF hello packets that are sent from a remote router and are destined for the local router.
   • Telnet traffic that is sent from a remote host and is destined for the local router.
   • SCP traffic that is destined for router's loopback interface.
   • SFTP traffic that enters one interface and is destined for a local physical interface.
   • SFTP traffic that enters and exits the same interface on the local router.

   If it is transit traffic, it is not exception traffic:
   - SCP traffic that enters one interface and exits another interface on a local router.
   - BGP updates that travel through the local router and are destined for a remote router.
   - Telnet traffic that travels through the local router and is destined for a remote end host.
   
   

2. Receive an alarm that Junos device is experiencing problems regarding temperature. show chassis temperature-thresholds and show chassis environment commands would use to investigate this problem.
   
   How to verify the component status, temperature, and cooling system:
   kb.juniper.net/InfoCenter/index?page=content&id=KB10969
   
   show chassis hardware command display a list of all Flexible PIC Concentrators (FPCs) and PICs installed on the router or switch chassis, including the hardware version level and serial number.
   
   show chassis pic fpc-slot <value> pic-slot <value> command display status information about the PIC installed in the specified FPC and PIC slot.
   

1. [edit system syslog]
   user@router# show
   host 152.170.10.10 {
       any warning;
   }
   file changes {
       change-log info;
   }
   
   • Any warning message will be sent to the 152.170.10.10 host.
   • Changes to the configuration will be logged.
     
   
   
2. If you want to back up device's current configuration to an archive site, can configure the router or switch to transfer its currently active configuration by FTP or secure copy (SCP) periodically or after each commit.
   www.juniper.net/documentation/en_US/junos/topics/task/configuration/junos-software-system-management-router-configuration-archiving.html#jd0e43
   
   
3. The packet is dropped from the network and The system sends an ICMP message back to the source of the packet when using the reject parameter as the next-hop value for a static route.
   set routing-options static route 10.1.1.1/32 reject
   www.juniper.net/documentation/en_US/junos/topics/reference/general/firewall-filter-actions-terminating.html
   
   
4. [edit policy-options] is hierarchy are routing policies defined.
   
   
5. set policy-options policy-statement <static-routes> term <exportstatic1> from protocol static
   set policy-options policy-statement<static-routes> term <exportstatic1> then accept
   set protocol ospf export<static-routes> command will apply a policy to redistribute static routes into OSPF.
   
   
6. show route forwarding-table command will display the contents of the forwarding table.
   
   
7. Commands allow to return to a previous version of software on the device:
   
   • request system software add <package-name>
   • request system software rollback
     
   
   
8. Cisco automatically resolves recursive routes. Those which next hop is not under directly connected interface. But Junos don't behave this way, so have to configure the resolve option.
   For example, Cisco configures using recursive routes:
   interface fast 0/0
     ip add 3.3.3.1 255.255.255.0
   ip route 1.1.1.0 255.255.255.0 2.2.2.2
   ip route 2.2.2.0 255.255.255.0 3.3.3.3
   Usually, the second static route is some dynamic learned route, this has no sense to configure two recursive statics.
   
   Under Junos this configure will be something like this:
   set interface fe-0/0/0 unit 0 family inet address 3.3.3.1/24
   set routing-options static route 1.1.1.0/24 next-hop 2.2.2.2 resolve
   set routing-options static route 2.2.2.0/24 next-hop 3.3.3.3
   If you don't use the resolve option, the first static router will be hidden because this has no an active next hop.
   
   
9. Dynamic routing can provide increased network availability when compared to static routing is an advantage of dynamic routing.
   
   
10. 110 represents the decimal equivalence of 01101110.
    
    
11. Must segment internal /24 network into a minimum of 12 subnets, each containing a minimum of 12 hosts. /28 network mask use.
    
    
12. [edit snmp]
    user@router# show
    community CommunityA {
        authorization read-only;
        clients {
            192.168.1.0/28;
        }
    }
    trap-group groupA {
        categories {
            link;
        }
        targets {
            192.168.100.1;
            192.168.200.1;
        }
    }
    
    • It specifies where to send traps is the purpose of the targets section of the configuration.
      
    
    
13. user@router> show route protocol static
    
    inet.0: 12 destinations, 12 routes (12 active, 0 holddown, 0 hidden)
    + = Active Route, - = Last Active, * = Both
    
    192.168.1.128/27   *[Static/5] 00:02:44
                        > to 10.20.106.10 via ge-0/0/5.0
    192.168.1.128/28   *[Static/5] 00:01:00
                        > to 10.85.229.26 via ge-0/0/0.0
    192.168.1.144/29   *[Static/5] 00:01:00
                        > to 10.85.229.26 via ge-0/0/0.0
    192.168.1.192/27   *[Static/5] 00:01:00
                        > to 10.18.1.1 via ge-0/0/1.0
    Given the routing entries are shown above, 10.20.106.10 next-hop IP address will be used for the destination IP address 192.168.1.159.
    
    
14. Issue the show chassis routing-engine command to view the details of your router's RE.
    
    • The temperature of the Routing Engine's CPU:
          CPU temperature             37 degrees C / 98 degrees F
      
    •     DRAM                      16330 MB (16384 MB installed)
      There is 16384 MB of DRAM installed.
    •     15 min CPU utilization:
            Idle                      99 percent
      The RE CPU idle utilization in the last 15 minutes is 99%
      
    •     Uptime                         124 days, 1 hour, 12 minutes, 55 seconds
      The RE has been powered up for 124 days, 1 hour, 12 minutes, 55 seconds.
      
      
15. 231 represents the decimal equivalence of 11100111.
    
    
16. > help ?
    Possible completions:
      <[Enter]>            Execute this command
      apropos              Find help information about a topic
      reference            Reference material
      syslog               System log error messages
      tip                  Tip for the day
      topic                Help for high-level topics
      |                    Pipe through a command
    
    
17. # load factory-default = Cisco writ era/commit rep: used to restore a Junos device to its default state.
    
    
18. On the 192.168.1.24/29 network, the minimum host address is 192.168.1.25, and the maximum host address is 192.168.1.30.
    
    
19. When troubleshooting ATM, ping atm vci 0.100 interface at-0/1/0 end-to-end command would allow testing reachability from one side of an ATM cloud to the other.
    www.juniper.net/documentation/en_US/junos/topics/reference/command-summary/ping-atm.html