This article helps you to understand the basics of Unilist.

This command will get you all the unilist id's running on the device.

show nsdb type unilist.

FPC0(PTX10008-r007 vty)# show nhdb type unilist    

  ID     Type     Interface   Next Hop Addr   Protocol      Encap    MTU              Flags PFE internal Flags

----- -------- ------------- --------------- ---------- ------------ ---- ------------------ ------------------

2097151  Unilist -             -                     IPv4            -    0 0x0000000000000000 0x0000020000000000

2097154  Unilist -             -                     IPv4            -    0 0x0000000000000000 0x0000020000000000

2097160  Unilist -             -                     IPv4            -    0 0x0000000000000000 0x0000020000000000

2097165  Unilist -             -                     IPv4            -    0 0x0000000000000000 0x0000020000000000

2097166  Unilist -             -                     IPv4            -    0 0x0000000000000000 0x0000020000000000

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In Junos OS, a unilist is constructed when there are multiple equally routable paths to reach a destination, such as via ISIS, LDP, or a static route. This unilist next hop isn't necessarily a physical next hop but a logical one, providing an index pointing to a hierarchical structure.

In normal conditions, the weight of a unilist next hop is typically 1, and you'll find the install information set to 'Yes', indicating that the route is installed over PFE.

However, if there are issues such as delays or one path going down, a weight is implemented against that route. In problematic situations, the weight of the unilist next hop may be set to 65535, and the install information would be set to 'No', indicating that the route is not installed over PFE.