Module 2 - Service Router Components & Command Line Interface

Question 1

Describe the Switch Fabric

Answer 1

• Allows a packet to move from the I/O card (Data Plane) where it enters the Service Router to the I/O card where it needs to exit the router
• Allows a control packet to move from the I/O card where it enters the router to the Control Processing Module (CPM) card where it needs to be processed
• Allows a control packet to move from the CPM to the I/O card where it needs to exit the router

Question 2

What are the different types of Input/Output Cards?

Answer 2

• Input/Output Module (IOM) & accompanying Media Dependent Adapter (MDA) cards
• Integrated Media Module (IMM) cards
• eXpandable Media Adapter (XMA) cards

Question 3

What are the different types of Input/Output Cards?

Answer 3

• Input/Output Module (IOM) & accompanying Media Dependent Adapter (MDA) cards
• Integrated Media Module (IMM) cards
• eXpandable Media Adapter (XMA) cards

Question 4

What is the order of data packet flow when egressing a Nokia 7750 SR?

Answer 4

SF/CPM -> IOM -> MDA -> SFP

Question 5

What are the files required for the Nokia 7750 SR boot process?

Answer 5

1. Boot Loader file (boot.ldr)
2. Boot Options File (bof.cfg)
3. Directory where the software image is loaded
4. Configuration File (config.cfg)

Question 6

What information is contained in the bof.cfg file?

Answer 6

• Management Port IP Address
• Location of the primary, secondary, and tertiary image files
• Location of the primary, secondary, and tertiary configuration files

Question 7

What information is contained in the config.cfg file?

Answer 7

Commands to configure cards, ports, layer-3 interfaces, routing protocols, MPLS tunnels, VPN services, QoS, and anything else configurable within the Nokia SR OS

Question 8

What are the steps taken when a Nokia SR OS system is being initalized?

Answer 8

1. Load & Execute the boot loader (boot.ldr)
2. Read & Apply the BOF initialization parameters (bof.cfg)
3. Get the runtime software image file from one of the specified locations
4. Once the SR OS is running get the configuration file (config.cfg) and execute the commands.

Question 9

What are the 3 management interfaces for SR OS devices?

Answer 9

• Classic: only classic commands, using either CLI or SNMP interfaces (default)
• Model-Driven: only model-driven commands for config changes, using either MD-CLI, NETCONF, or gRPC/gNMI interfaces. also read-only access to CLI & SNMP classic interfaces
• Mixed: Read/Write access to both classing & MD management interfaces (With limitations)

Question 10

What configuration edit modes are available in MD-CLI?

Answer 10

• Global: Allows a user to see and modify the global candidate configuration in a non-exclusive mode
• Exclusive: Allows a user to modify the global configuration in an exclusive mode, but other users can see the changes being made
• Read-Only: Allows a user to see the changes being made by other users, in either global or exclusive mode, to the global candidate configuration
• Private: Allows a user to create their own private candidate configuration in an exclusive mode; no other users can see or modify the private candidate configuration.

Question 11

What are the 4 types of event categories?

Answer 11

• Security: Related to attempts to breach system security (e.g. failed logins)
• Change: Related to changes in the config and operation of the node
• Debug: Generated due to debug commands issued by the administrator
• Main: All other events

Question 12

What are the 6 severity levels of events?

Answer 12

• Cleared
• Indeterminate (information only)
• Critical (most severe)
• Major
• Minor
• Warning (least severe)

Question 13

What destinations are available for event logging?

Answer 13

• Console: Sent to the active session on the system console
• CLI: sent to the active telnet or SSH session of users who subscribe to receive messages
• File: Sent to a circular file in the compact flash cards (old data is overwritten)
• Memory: Sent to a circular buffer in memory
• Syslog: Sent to a syslog server identified by its IP address
• SNMP: set to SNMP trap receivers
• NETCONF: sent to the active NETCONF session as notifications

Question 14

What are the steps to configure an event log?

Answer 14

1. Create an event log with an ID between 1 and 97 (98 - 100 are reserved)
2. Select the categories of events that will be registered (one or more)
3. Optional: configure & apply a filter to be more specific about the event messages of interest regarding their severity, corresponding application, or whether they include/exclude some words
4. Select the destination of the event log

Question 15

What are the pre-configured default event logs?

Answer 15

• log-id 99: Default System Log
• log-id 100: Default Serious Errors Log
• log-id 101: netconf

Question 16

What are the cli commands to modify the bof (boot options file)?

Answer 16

edit-config bof exclusive
bof router “management”
interface “management” cpm active ipv4 ip-address 172.16.2.4
interface “management” cpm active ipv4 ip-address prefix-length 27
static-routes route 128.0.0.0/1 next-hop 172.16.2.1
commit

Question 17

What is the CLI command for configuring the system name?

Answer 17

configure system name “new_sys_name”
commit
quit-config

Question 18

What are the main functions of the control plane?

Answer 18

• Support management functions of the router
• build the forwarding table information
• handled routing protocols messaging

Question 19

What are the main functions of the data plane?

Answer 19

• Receive, process, and transmit user application traffic using the forwarding tables populated by the control pane

Question 20

What is a managment datastore and how many types are there in a Nokia 7750 SR?

Answer 20

It is a tree-shaped data structure where management information is stored and there are 2 types

• Configuration datastore
• State datastore