



Individual Submission                                      Abhishek Garg
Internet-Draft                                                     Ciena
Intended status: Informational                             15 April 2026
Expires: 17 October 2026


    Auto-Deletion of Unused TE Tunnels Using a Timer-Based Mechanism
              draft-garg-auto-delete-unused-te-tunnels-00

Abstract

   This document describes a timer-based mechanism for handling unused
   Traffic Engineering (TE) tunnels.

   When a tunnel remains inactive for a configured period, it is moved
   to a parked state, administratively shut down, and the associated
   resources are released.

   If the tunnel remains parked beyond a longer retention interval, it
   may be deleted automatically or removed through operator action,
   depending on local policy.

   This approach improves resource utilization and provides a structured
   lifecycle for unused TE tunnels.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 17 October 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Proposed Solution . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Detailed Mechanism  . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Inactivity Detection and Parking  . . . . . . . . . . . .   3
     4.2.  Retention and Deletion  . . . . . . . . . . . . . . . . .   4
   5.  Example . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Informative References  . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Traffic Engineering (TE) tunnels are widely used in transport and IP/
   MPLS networks to steer traffic and provide deterministic forwarding
   behavior.  Common examples include RSVP-TE tunnels, described in
   [RFC3209], and Segment Routing Traffic Engineering (SR-TE) policies,
   which build on Segment Routing concepts described in [RFC8402] and
   are specified in [RFC9256].

   Over time, some TE tunnels become inactive but remain provisioned on
   the router.  Even when they are no longer carrying traffic, such
   tunnels may continue to consume labels, BFD state, session state,
   memory, and other operational resources.

   This document describes a mechanism to manage unused TE tunnels
   through a parking state and a timer-based deletion policy.  The
   mechanism is intended to improve resource efficiency while preserving
   operator control over tunnel lifecycle management.









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2.  Problem Statement

   Unused TE tunnels can remain configured in the network for long
   periods without carrying traffic.  Such tunnels may still consume
   forwarding state, labels, BFD sessions, system memory, and other
   tunnel-related resources.

   The problem becomes more significant in networks containing large
   numbers of TP co-routed tunnels, RSVP-TE tunnels, and SR-TE tunnels.
   As the number of provisioned tunnels grows, manual identification and
   cleanup of unused tunnels becomes increasingly difficult.

   A mechanism is therefore needed to identify inactive tunnels, release
   their associated resources in a controlled manner, and optionally
   delete them after extended inactivity.

3.  Proposed Solution

   This document proposes a two-stage lifecycle mechanism for unused TE
   tunnels: parking and deletion.

   In the first stage, a tunnel that remains inactive for a configurable
   interval is moved to a parked state.  When the tunnel is parked, the
   system administratively deactivates the tunnel and releases the
   associated resources.  This may include BFD sessions associated with
   the parked tunnel, for example those defined by [RFC5880].

   In the second stage, a deletion policy is applied to tunnels that
   remain parked for a longer retention interval.  Depending on local
   policy, the tunnel may be deleted automatically after an alarm is
   raised, or retained until the operator explicitly removes it.

   This approach reduces resource consumption and provides a predictable
   operational method for handling long-term unused TE tunnels.

4.  Detailed Mechanism

4.1.  Inactivity Detection and Parking

   The system continuously monitors tunnel activity.  A tunnel may be
   considered inactive when no control-plane or data-plane activity is
   observed for a configured period.

   When the inactivity threshold is reached, the system moves the tunnel
   into a parked state and records the tunnel in a dedicated parking
   table or database.





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   When a tunnel is parked, the system places it in administratively
   shut state and releases the resources associated with that tunnel.
   Depending on the tunnel type, this may include labels, bandwidth-
   related state, BFD sessions, and protocol session state.

4.2.  Retention and Deletion

   A parked tunnel may be restored to service at any time by operator
   action.  If the operator issues an administrative no shut command
   before the retention timer expires, the tunnel returns to active
   state.

   If a tunnel remains parked beyond the configured retention interval,
   the system evaluates the deletion policy.  In an automatic deletion
   mode, the system raises an alarm and then removes the tunnel after
   the configured grace period.  In a manual deletion mode, the system
   raises an alarm and retains the tunnel until it is explicitly deleted
   by the operator.

5.  Example

   Figure 1 illustrates the operational flow for parking and deleting an
   unused TE tunnel.

           +-------+
           | Start |
           +-------+
               |
               v
             +----------------+
             | Monitor tunnel |
             | activity/stats |
             +----------------+
               |
               v
             +-------------------+
             | Inactive > 7 days?|
             +-------------------+
               Y |             | N
           v             v
             +---------------+ +--------+
             | Park tunnel,  | | Active |
             | admin shut,   | +--------+
             | free resrcs   |
             +---------------+
               |
               v
             +----------------+



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             | Admin no shut? |----Y----> Active
             +----------------+
               |
               N
               v
             +-------------------+
             | Parked > 90 days? |
             +-------------------+
               |
               v
             +------------------+
             | Auto-delete on ? |
             +------------------+
               Y |            | N
           v            v
             +------------+ +---------------+
             | Alarm and  | | Alarm and wait|
             | delete     | | admin delete  |
             +------------+ +---------------+
           |              |
           v              v
               +-----+        +-----+
               | End |        | End |
               +-----+        +-----+

                         Figure 1: Operational Flow

   Consider a TE tunnel T1 provisioned between PE1 and PE2.  The node
   monitors tunnel usage to determine whether the tunnel remains active.

   If T1 remains inactive for more than 7 days, the node moves the
   tunnel to the park table, updates the corresponding database entry,
   places the tunnel in administratively shut state, and releases the
   associated resources.

   If an operator issues an administrative no shut command before the
   parked interval reaches 90 days, T1 returns to active service.

   If T1 remains parked for more than 90 days, the node evaluates the
   configured deletion policy.  If automatic deletion is enabled, the
   node generates an alarm and deletes the tunnel.  Otherwise, the node
   generates an alarm and retains the tunnel until it is manually
   deleted by the operator.








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   The operational sequence is therefore as follows: monitor tunnel
   activity, park the tunnel after the inactivity threshold, allow
   administrative reactivation during the retention interval, and apply
   either automatic or manual deletion after the retention period
   expires.

6.  Security Considerations

   This document describes operational behavior that can affect tunnel
   availability and resource allocation.  Unauthorized or incorrect
   administrative actions could cause active tunnels to be parked or
   deleted unexpectedly.

   Implementations should ensure that only authorized management
   entities can configure inactivity thresholds, retention timers,
   deletion policies, or administrative reactivation and deletion
   actions.

   Operators should also consider safeguards for alarms, audit logs, and
   policy review to reduce the risk of unintended tunnel removal.

7.  IANA Considerations

   This document has no IANA actions.

8.  References

8.1.  Informative References

   [RFC3209]  Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
              and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
              Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
              <https://www.rfc-editor.org/info/rfc3209>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC9256]  Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
              A., and P. Mattes, "Segment Routing Policy Architecture",
              RFC 9256, DOI 10.17487/RFC9256, July 2022,
              <https://www.rfc-editor.org/info/rfc9256>.




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Author's Address

   Abhishek Garg
   Ciena
   Email: abhishekgarg.vip@gmail.com














































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