Automatic Autobandwidth Adjustment

Purpose

Automatic autobandwidth allocation allows an MPLS tunnel to automatically adjust its bandwidth allocation based on the volume of traffic flowing through the tunnel. Bandwidth allocation is adjusted according to a specified time interval. At the end of the time interval specified at the [edit protocols mpls label-switched-path auto-bandwidth] hierarchy level, the current maximum average bandwidth usage is compared with the allocated bandwidth for the LSP. If the LSP needs more bandwidth, an attempt is made to set up a new path where bandwidth is equal to the current maximum average usage. If the attempt is successful, the LSP's traffic is routed through the new path and the old path is removed. If the attempt fails, the LSP continues to use its current path.

For more information on configuring autobandwidth, see the JUNOS MPLS Applications Configuration Guide.

Autobandwidth success and failure is logged in the output of the show mpls lsp extensive command. The following manual autobandwidth adjustment events are included in this section:

• Automatic Autobandwidth Adjustment Failed Event
• Automatic Autobandwidth Adjustment Succeeded Event

Automatic Autobandwidth Adjustment Failed Event

LSP Event

Autobw adjustment failed

Sample Output 1

user@R1> show configuration protocols mpls 

statistics {

    file auto-bw.log;

    interval 5;

    auto-bandwidth;

}

label-switched-path R1-to-R6 {

    to 10.0.0.6;

    auto-bandwidth {

        adjust-interval 300;

        adjust-threshold 10;

        minimum-bandwidth 5m;

        maximum-bandwidth 80m;

    }

}

label-switched-path R1-to-R3 {

    to 10.0.0.3;

    auto-bandwidth {

        adjust-interval 300;

        adjust-threshold 10;

        minimum-bandwidth 155m;

        maximum-bandwidth 155m;

    }

}

Sample Output

user@R1> show mpls lsp extensive

Ingress LSP: 3 sessions

10.0.0.3

  From: 10.0.0.1, State: Up, ActiveRoute: 5, LSPname: R1-to-R3

  ActivePath:  (primary)

  LoadBalance: Random

  Metric: 1

  Autobandwidth 

  MinBW: 155Mbps MaxBW: 155Mbps

  AdjustTimer: 300 secs AdjustThreshold: 10%

  Max AvgBW util: 192bps, Bandwidth Adjustment in 219 second(s).

  Encoding type: Packet, Switching type: Packet, GPID: IPv4

 *Primary                    State: Up

    Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 10)

 10.1.13.2 S 

    Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 
10=SoftPreempt):

          10.1.13.2

    7 Feb 17 15:41:12 Autobw adjustment failed

    6 Feb 17 15:41:12 CSPF failed: no route toward 10.0.0.3

    5 Feb 17 15:36:23 Selected as active path

    4 Feb 17 15:36:23 Record Route:  10.1.13.2

    3 Feb 17 15:36:23 Up

    2 Feb 17 15:36:23 Originate Call

    1 Feb 17 15:36:23 CSPF: computation result accepted

  Created: Thu Feb 17 15:36:23 2005 

[...Output truncated...]

What It Means

This LSP event indicates that a periodic (timer-based) autobandwidth adjustment for the LSP is triggered at the end of the adjust interval. The adjustment fails, and the LSP stays up on the existing path with its current bandwidth.

Cause

Adjustment failure may be due to a path CSPF computation failure with the adjust bandwidth or a signaling failure on the new path.

At the end of the time interval specified at the [edit protocols mpls label-switched-path auto-bandwidth] hierarchy level, the current maximum average bandwidth usage is compared to the allocated bandwidth for the LSP. If the LSP needs more bandwidth, an attempt is made to set up a new path where bandwidth is equal to the current maximum average usage. If the attempt is successful, the LSP's traffic is routed through the new path and the old path is removed. If the attempt fails, the LSP continues to use its current path.

Action

Take action appropriate to the situation:

• Verify the MPLS and RSVP configuration on all available paths to the LSP endpoint.
• Check available bandwidth on alternate paths using the show rsvp interface command. If not enough bandwidth is available on any available paths, adjust the minimum-bandwidth parameter for the LSP in order to establish or adjust the priority to allow the LSP to preempt another LSP of lesser priority. For an LSP to be preempted, its hold priority must be lower than the LSP you are trying to establish.

Automatic Autobandwidth Adjustment Succeeded Event

LSP Event

Autobw adjustment succeeded

Sample Output 1

user@R1> show configuration protocols mpls 

statistics {

    file auto-bw.log;

    interval 5;

    auto-bandwidth;

}

label-switched-path R1-to-R6 {

    to 10.0.0.6;

    auto-bandwidth {

        adjust-interval 300;

        adjust-threshold 10;

        minimum-bandwidth 10m;

        maximum-bandwidth 80m;

    }

}

Sample Output 2

user@host> show mpls lsp extensive

[...Output truncated...]

Ingress LSP: 1 sessions

10.0.0.6

  From: 10.0.0.1, State: Up, ActiveRoute: 0, LSPname: R1-to-R6

  ActivePath:  (primary)

  LoadBalance: Random

  Autobandwidth 

  MinBW: 10Mbps MaxBW: 80Mbps

  AdjustTimer: 300 secs AdjustThreshold: 10%

  Max AvgBW util: 0bps, Bandwidth Adjustment in 282 second(s).

  Encoding type: Packet, Switching type: Packet, GPID: IPv4

 *Primary                    State: Up

    Bandwidth: 10Mbps 

    Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 20)

 10.1.13.2 S 10.1.36.2 S 

    Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 
10=SoftPreempt):

          10.1.13.2 10.1.36.2

    9 Feb 17 14:41:12 Record Route:  10.1.13.2 10.1.36.2

    8 Feb 17 14:41:12 Up

    7 Feb 17 14:41:12 Autobw adjustment succeeded

    6 Feb 17 14:41:12 CSPF: computation result accepted

    5 Feb 17 14:36:29 Selected as active path

    4 Feb 17 14:36:29 Record Route:  10.1.13.2 10.1.36.2

    3 Feb 17 14:36:29 Up

    2 Feb 17 14:36:29 Originate Call

    1 Feb 17 14:36:29 CSPF: computation result accepted

  Created: Thu Feb 17 14:36:29 2005

Total 1 displayed, Up 1, Down 0

[...Output truncated...]

What It Means

This LSP event indicates that a periodic (timer-based) autobandwidth adjustment for the LSP is triggered at the end of the adjust interval. A new path for the LSP, with the adjusted bandwidth, is successfully computed and signaled. The LSP (and traffic) switches over to the new adjusted path.

Cause

At the end of the time interval specified at the [edit protocols mpls label-switched-path auto-bandwidth] hierarchy level, the current maximum average bandwidth usage is compared to the allocated bandwidth for the LSP. If the LSP needs more bandwidth, an attempt is made to set up a new path where bandwidth is equal to the current maximum average usage. If the attempt is successful, the LSP's traffic is routed through the new path and the old path is removed. If the attempt fails, the LSP continues to use its current path.

Action

No action required. Automatic autobandwidth adjustment succeeded.