System Management Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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System Management Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Virtual terminals

Updated: June 12, 2026

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This section explains virtual terminals, which enable remote access and administration of the network device.

A virtual terminal is a router management interface that

  • provides remote access to the device using Telnet or SSH,

  • operates independently of physical connections, and

  • is identified by a unique vty identifier assigned according to connection order.

vty lines: The software-maintained logical lines that facilitate multiple virtual terminal sessions.

  • Physical location is not applicable for virtual terminals, as all sessions are established virtually.

  • The Cisco IOS XR software assigns a vty identifier to each vty session based on establishment sequence.

Connecting to a router using ssh admin@router-ip uses a virtual terminal line.

Vty pools

A vty pool is a connection management construct that

  • groups multiple virtual terminal lines (vtys) into logical pools,

  • applies a common line template configuration to all member vtys, and

  • allows flexible division of remote access connections for role- or service-based segmentation.

  • Default vty pool: Consists of five vtys (vtys 0 through 4) that each reference the default line template.

  • Default fault manager pool: Consists of six vtys (vtys 100 through 105) that each reference the default line template.

  • User-defined vty pool: In addition to the default vty pool and default fault manager pool, you can configure a user-defined vty pool that can reference the default template or a user-defined template.

Guidelines for vty Pools

  • The vty range for the default pool must start at vty 0 and include at least five vtys.

  • The vty range from 0 through 99 can reference the default vty pool.

  • Resize the default vty pool by increasing the range of vtys as needed.

  • The vty range from 5 through 99 can reference a user-defined vty pool.

  • If the default vty pool is resized, start the next available user-defined pool at the first free vty (e.g., after resizing vty 0-9 for the default, begin the next at 10).

  • The vty range from 100 is reserved for the fault manager vty pool, which must start at vty 100 and include at least six vtys.

  • A vty can belong to only one pool; configuration fails if a vty is assigned elsewhere.

  • Attempting to remove an active vty from its pool during configuration causes the operation to fail.