JUNOS Enterprise Routing

Chapter Review Answers

1. Answer: B, C. The T640 and M320 are valid Juniper Networks router models but are usually deployed in service provider networks.

2. Answer: D. The Routing Engine is the component in the router that controls all management functions, including commands that would be used to debug the router.

3. Answer: False. The J-series routers do contain a virtualized PFE with API and sockets replacing the ASICs that are found in the M-series routers.

4. Answer: C. The CLI is actually a process that runs off the kernel, called mgd. Of the other services listed, clid is invalid, rpd controls the routing process, and inetd manages network services.

5. Answer: A. Request commands are used to issue system-wide functions such as rebooting the router. The rest of the options are invalid CLI commands.

6. Answer: A. The pipe command match will find every occurrence of a string in the output of the command. The find command will locate the first occurrence of the string, search is an invalid option, and hold will hold text without exiting the -More-- prompt.

7. Answer: C. There is no password to enter configuration mode. Users are allowed into configuration mode based on access privileges.

8. Answer: B. To change the directory in configuration mode, use the edit command.

9. Answer: D. To activate the changes in the router, issue a commit command. Of the remaining options, copy and save are valid CLI commands but are used for configuration management.

10. Answer: C. When at the top level of the configuration tree, the CLI banner will display the [edit] prompt.

11. Answer: A. The first archive is stored in rollback 1. rollback 0 is used to copy the active configuration to the candidate configuration, and the other options are not valid rollback commands.

12. Answer: B. The help topic command displays general information about any topic referenced in the Juniper documentation. The actual output of the command is as follows:

    lab@P1R1>help topic layer3-vpns overview
    Layer 3 VPN Overview
    
       In JUNOS software, Layer 3 VPNs are based on RFC 2547bis. RFC
       2547bis defines a mechanism by which service providers can use
       their IP backbones to provide VPN services to their customers. A
       VPN is a set of sites that share common routing information and
       Layer 3 whose connectivity is controlled by a collection of
       policies. The sites that make up a Layer 3 VPN are connected over
       a provider's existing public Internet backbone.
    
       RFC 2547bis VPNs are also known as BGP/MPLS VPNs because BGP is
       used to distribute VPN routing information across the provider's
       backbone, and MPLS is used to forward VPN traffic across the VPN
       backbone to remote sites.
    
       Customer networks, because they are private, can use either public
       addresses or private addresses, as defined in RFC 1918, Address
       Allocation for Private Internets. When customer networks that use
       private addresses connect to the public Internet infrastructure,
       overlap with the same private addresses used by other network
       users the private addresses might MPLS/BGP VPNs solve this problem
       by adding a VPN identifier prefix to each address from a
       particular VPN site, thereby creating an address that is unique
       to the VPN and within the public Internet. In addition, each VPN has
       both within its own VPN-specific routing table that contains the
       routing information for that VPN only.