15 mins read
RSVP – Secondary Paths
1. Intro
In the previous example we tested link coloring with multiple LSPs to the same destination, which is not ideal. In this post we will configure Secondary paths.
By default, when network failures occur along the path of RSVP signaled LSPs, traffic will be dropped. The ingress LSR continues to send traffic until a PathTear message arrives. Then the ingress LSR will try to signal new path if possible. RSVP provides different traffic protection mechanisms, which can significantly improve network restoration.
Secondary paths are established only if the primary path fails. After failure the ingress router always tries to establish the primary path again. An LSP can only have one primary path, but multiple secondary paths are allowed. Secondary paths are signaled in the order they appear in the configuration.
Specifying standby under the secondary path forces the LSR to signal the path even though the primary has not failed yet. The Ingress router pushes traffic only to the primary path. The secondary path will already be established, but still waits until the primary fails. This reduces failover times as the secondary path is pre-established, but also requires additional state in the LSRs for the standby LSPs.
It is recommended for the primary and secondary path to have constraints (ERO or link coloring) defined so that it is sure that they pass different LSRs in the network.
If a secondary path is configured the ingress LSR fails over to it even though there is another physical path that complies the primary path constraints. When the ingress LSR signals the primary path on different physical path, traffic is reverted back from the secondary path to the new primary path.
By default, the minimum time that the primary path must be UP before the traffic to revert to it is 60 seconds. By configuring that timer to 0 ensures the LSP will not revert back to the primary path. Another way to disable the revert-timer is to configure two secondary paths instead of configuring a primary and a secondary path.
WE will use the same topology.
2. Primary and Secondary paths
Instead of having 2 LSPs to R7, we will configure one LSP with a Primary and Secondary paths:
### The initial config:
set protocols mpls label-switched-path TO-R7 to 17.0.0.7
set protocols mpls label-switched-path TO-R7 admin-group include-any BLUE
set protocols mpls label-switched-path TO-R7-backup to 17.0.0.7
set protocols mpls label-switched-path TO-R7-backup admin-group exclude BLUE
### Delete both paths:
delete protocols mpls label-switched-path TO-R7
delete protocols mpls label-switched-path TO-R7-backup
### Recreate from scratch:
set protocols mpls label-switched-path TO-R7 to 17.0.0.7
set protocols mpls label-switched-path TO-R7 primary BLUE-PATH admin-group include-any BLUE
set protocols mpls label-switched-path TO-R7 secondary RED-PATH admin-group exclude BLUE
### We must configure BLUE-PATH and RED-PATH, but they will be empty:
set protocols mpls path BLUE-PATH
set protocols mpls path RED-PATH
### Full config will look like this:
root@R1# show protocols mpls | display set
set protocols mpls admin-groups BLUE 0
set protocols mpls admin-groups GREEN 1
set protocols mpls admin-groups RED 2
set protocols mpls label-switched-path TO-R7 to 17.0.0.7
set protocols mpls label-switched-path TO-R7 primary BLUE-PATH admin-group include-any BLUE
set protocols mpls label-switched-path TO-R7 secondary RED-PATH admin-group exclude BLUE
set protocols mpls path BLUE-PATH
set protocols mpls path RED-PATH
set protocols mpls interface ge-0/0/2.0 admin-group BLUE
set protocols mpls interface ge-0/0/1.0 admin-group RED
set protocols mpls interface ge-0/0/1.0 admin-group GREEN
### With this config we only have one LSP to R7:
root@R1# run show route table inet.3
inet.3: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
17.0.0.7/32 *[RSVP/7/1] 00:00:26, metric 3000
> to 17.1.3.3 via ge-0/0/2.0, label-switched-path TO-R7
### Again, the LSP is UP:
root@R1# run show rsvp session
Ingress RSVP: 1 sessions
To From State Rt Style Labelin Labelout LSPname
17.0.0.7 17.0.0.1 Up 0 1 FF - 299984 TO-R7
Total 1 displayed, Up 1, Down 0
Egress RSVP: 1 sessions
To From State Rt Style Labelin Labelout LSPname
17.0.0.1 17.0.0.7 Up 0 1 FF 3 - TO-R1
Total 1 displayed, Up 1, Down 0
Transit RSVP: 0 sessions
Total 0 displayed, Up 0, Down 0
### The extensive version:
root@R1# run show mpls lsp name TO-R7 extensive
Ingress LSP: 1 sessions
17.0.0.7
From: 17.0.0.1, State: Up, ActiveRoute: 0, LSPname: TO-R7, LSPid: 2
ActivePath: BLUE-PATH (primary)
LSPtype: Static Configured, Penultimate hop popping
LoadBalance: Random
Follow destination IGP metric
Encoding type: Packet, Switching type: Packet, GPID: IPv4
LSP Self-ping Status : Enabled
*Primary BLUE-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Include Any: BLUE
Flap Count: 7
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 3000)
17.1.3.3 S 17.3.6.6 S 17.6.7.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.3.3(Label=299984) 17.3.6.6(Label=299984) 17.6.7.7(Label=3)
117 Jul 23 04:50:32.864 Selected as active path
116 Jul 23 04:50:32.863 Self-ping ended successfully
115 Jul 23 04:50:32.680 Up
114 Jul 23 04:50:32.680 Self-ping started
113 Jul 23 04:50:32.680 Self-ping enqueued
112 Jul 23 04:50:32.680 Record Route: 17.1.3.3(Label=299984) 17.3.6.6(Label=299984) 17.6.7.7(Label=3)
111 Jul 23 04:50:32.645 LSP-ID: 8 created
110 Jul 23 04:50:32.645 Originate Call
109 Jul 23 04:50:32.645 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
[...]
Secondary RED-PATH State: Dn
Priorities: 7 0
SmartOptimizeTimer: 180
Exclude: BLUE
Flap Count: 0
MBB Count: 0
No computed ERO.
Created: Wed Jul 22 07:54:38 2026
Total 1 displayed, Up 1, Down 0
Egress LSP: 1 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
### In case there is problem on the Primary path, then the Secondary will come UP:
root@R1# run show mpls lsp name TO-R7 extensive
Ingress LSP: 1 sessions
17.0.0.7
From: 17.0.0.1, State: Up, ActiveRoute: 0, LSPname: TO-R7, LSPid: 2
ActivePath: RED-PATH (secondary)
LSPtype: Static Configured, Penultimate hop popping
LoadBalance: Random
Follow destination IGP metric
Encoding type: Packet, Switching type: Packet, GPID: IPv4
LSP Self-ping Status : Enabled
Primary BLUE-PATH State: Dn
Priorities: 7 0
SmartOptimizeTimer: 180
Include Any: BLUE
Flap Count: 8
MBB Count: 0
Will be enqueued for recomputation in 9 second(s).
125 Jul 23 04:55:34.171 CSPF failed: no route toward 17.0.0.7
124 Jul 23 04:55:34.171 CSPF: link down/deleted: 17.6.7.6(17.0.0.6:359)(17.0.0.6)->17.6.7.7(17.0.0.7:0)(17.0.0.7)
123 Jul 23 04:55:27.178 Deselected as active
122 Jul 23 04:55:27.178 CSPF failed: no route toward 17.0.0.7
121 Jul 23 04:55:27.178 Clear Call: CSPF computation failed
120 Jul 23 04:55:27.178 ResvTear received
119 Jul 23 04:55:27.177 17.1.3.1: Down
118 Jul 23 04:55:27.177 17.3.6.6: Session preempted
117 Jul 23 04:50:32.864 Selected as active path
116 Jul 23 04:50:32.863 Self-ping ended successfully
115 Jul 23 04:50:32.680 Up
114 Jul 23 04:50:32.680 Self-ping started
113 Jul 23 04:50:32.680 Self-ping enqueued
112 Jul 23 04:50:32.680 Record Route: 17.1.3.3(Label=299984) 17.3.6.6(Label=299984) 17.6.7.7(Label=3)
111 Jul 23 04:50:32.645 LSP-ID: 8 created
110 Jul 23 04:50:32.645 Originate Call
109 Jul 23 04:50:32.645 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
108 Jul 23 04:46:34.253 Deselected as active
107 Jul 23 04:46:34.252 Clear Call: Disable null path
106 Jul 23 04:37:47.788 Selected as active path
105 Jul 23 04:37:47.787 Self-ping ended successfully
104 Jul 23 04:37:46.925 Up
103 Jul 23 04:37:46.925 Self-ping started
102 Jul 23 04:37:46.925 Self-ping enqueued
101 Jul 23 04:37:46.925 Record Route: 17.1.3.3(Label=299968) 17.3.6.6(Label=299968) 17.6.7.7(Label=3)
100 Jul 23 04:37:46.891 LSP-ID: 7 created
99 Jul 23 04:37:46.891 Originate Call
98 Jul 23 04:37:46.891 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
97 Jul 23 04:37:29.360 CSPF failed: no route toward 17.0.0.7
96 Jul 23 04:37:29.360 CSPF: link down/deleted: 17.6.7.6(17.0.0.6:359)(17.0.0.6)->17.6.7.7(17.0.0.7:0)(17.0.0.7)
95 Jul 23 04:37:17.621 CSPF failed: no route toward 17.0.0.7
94 Jul 23 04:37:17.620 Deselected as active
93 Jul 23 04:37:17.620 CSPF failed: no route toward 17.0.0.7
92 Jul 23 04:37:17.620 Clear Call: CSPF computation failed
91 Jul 23 04:37:17.619 ResvTear received
90 Jul 23 04:37:17.619 17.1.3.1: Down
89 Jul 23 04:37:17.619 17.3.6.6: Session preempted
88 Jul 23 03:08:01.147 Selected as active path
87 Jul 23 03:08:01.146 Self-ping ended successfully
86 Jul 23 03:08:00.183 Up
85 Jul 23 03:08:00.183 Self-ping started
84 Jul 23 03:08:00.183 Self-ping enqueued
83 Jul 23 03:08:00.183 Record Route: 17.1.3.3(Label=299920) 17.3.6.6(Label=299920) 17.6.7.7(Label=3)
82 Jul 23 03:08:00.121 LSP-ID: 6 created
81 Jul 23 03:08:00.121 Originate Call
80 Jul 23 03:08:00.121 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
79 Jul 23 02:52:47.286 CSPF failed: no route toward 17.0.0.7
78 Jul 23 02:52:47.286 CSPF: link down/deleted: 17.8.1.1(17.0.0.1:358)(17.0.0.1)->17.8.1.2(17.0.0.3:0)(17.0.0.3)
77 Jul 23 02:52:47.284 CSPF failed: no route toward 17.0.0.7
76 Jul 23 02:52:47.283 Clear Call: CSPF computation failed
*Secondary RED-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Exclude: BLUE
Flap Count: 0
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 5000)
17.1.2.2 S 17.2.4.4 S 17.4.5.5 S 17.5.8.8 S 17.7.8.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.2.2(Label=299872) 17.2.4.4(Label=299872) 17.4.5.5(Label=299872) 17.5.8.8(Label=299888) 17.7.8.7(Label=3)
9 Jul 23 04:55:27.805 Selected as active path
8 Jul 23 04:55:27.804 Self-ping ended successfully
7 Jul 23 04:55:27.231 Up
6 Jul 23 04:55:27.231 Self-ping started
5 Jul 23 04:55:27.231 Self-ping enqueued
4 Jul 23 04:55:27.230 Record Route: 17.1.2.2(Label=299872) 17.2.4.4(Label=299872) 17.4.5.5(Label=299872) 17.5.8.8(Label=299888) 17.7.8.7(Label=3)
3 Jul 23 04:55:27.179 LSP-ID: 9 created
2 Jul 23 04:55:27.179 Originate Call
1 Jul 23 04:55:27.179 CSPF: computation result accepted 17.1.2.2 17.2.4.4 17.4.5.5 17.5.8.8 17.7.8.7
Created: Wed Jul 22 07:54:38 2026
Total 1 displayed, Up 1, Down 0
Egress LSP: 1 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0So, this time we saw one LSP with 2 different paths, if one fails the other is established. But, we will have some packet loss during the switchover from Primary to Secondary path; it takes time for the Secondary path to be signaled.
3. Standby path
There is a solution to this, we can configure the Secondary path as hot standby:
### Configure the Secondary path as standby:
root@R1# set protocols mpls label-switched-path TO-R7 secondary RED-PATH standby
[edit]
root@R1# show | compare
[edit protocols mpls label-switched-path TO-R7 secondary RED-PATH]
+ standby;
### Both Primary and Secondary are UP:
root@R1# run show mpls lsp name TO-R7 extensive
Ingress LSP: 1 sessions
17.0.0.7
From: 17.0.0.1, State: Up, ActiveRoute: 0, LSPname: TO-R7, LSPid: 2
ActivePath: BLUE-PATH (primary)
LSPtype: Static Configured, Penultimate hop popping
LoadBalance: Random
Follow destination IGP metric
Encoding type: Packet, Switching type: Packet, GPID: IPv4
LSP Self-ping Status : Enabled
*Primary BLUE-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Include Any: BLUE
Flap Count: 8
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 3000)
17.1.3.3 S 17.3.6.6 S 17.6.7.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.3.3(Label=300000) 17.3.6.6(Label=300000) 17.6.7.7(Label=3)
134 Jul 23 04:59:27.189 Selected as active path: due to 'primary'
133 Jul 23 04:58:27.368 Self-ping ended successfully
132 Jul 23 04:58:26.413 Up
131 Jul 23 04:58:26.413 Self-ping started
130 Jul 23 04:58:26.413 Self-ping enqueued
129 Jul 23 04:58:26.413 Record Route: 17.1.3.3(Label=300000) 17.3.6.6(Label=300000) 17.6.7.7(Label=3)
128 Jul 23 04:58:21.624 LSP-ID: 10 created
127 Jul 23 04:58:21.624 Originate Call
126 Jul 23 04:58:21.624 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
125 Jul 23 04:55:34.171 CSPF failed: no route toward 17.0.0.7
124 Jul 23 04:55:34.171 CSPF: link down/deleted: 17.6.7.6(17.0.0.6:359)(17.0.0.6)->17.6.7.7(17.0.0.7:0)(17.0.0.7)
123 Jul 23 04:55:27.178 Deselected as active
122 Jul 23 04:55:27.178 CSPF failed: no route toward 17.0.0.7
121 Jul 23 04:55:27.178 Clear Call: CSPF computation failed
120 Jul 23 04:55:27.178 ResvTear received
119 Jul 23 04:55:27.177 17.1.3.1: Down
118 Jul 23 04:55:27.177 17.3.6.6: Session preempted
117 Jul 23 04:50:32.864 Selected as active path
116 Jul 23 04:50:32.863 Self-ping ended successfully
115 Jul 23 04:50:32.680 Up
114 Jul 23 04:50:32.680 Self-ping started
113 Jul 23 04:50:32.680 Self-ping enqueued
112 Jul 23 04:50:32.680 Record Route: 17.1.3.3(Label=299984) 17.3.6.6(Label=299984) 17.6.7.7(Label=3)
111 Jul 23 04:50:32.645 LSP-ID: 8 created
110 Jul 23 04:50:32.645 Originate Call
109 Jul 23 04:50:32.645 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
108 Jul 23 04:46:34.253 Deselected as active
107 Jul 23 04:46:34.252 Clear Call: Disable null path
106 Jul 23 04:37:47.788 Selected as active path
105 Jul 23 04:37:47.787 Self-ping ended successfully
104 Jul 23 04:37:46.925 Up
103 Jul 23 04:37:46.925 Self-ping started
102 Jul 23 04:37:46.925 Self-ping enqueued
101 Jul 23 04:37:46.925 Record Route: 17.1.3.3(Label=299968) 17.3.6.6(Label=299968) 17.6.7.7(Label=3)
100 Jul 23 04:37:46.891 LSP-ID: 7 created
99 Jul 23 04:37:46.891 Originate Call
98 Jul 23 04:37:46.891 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
97 Jul 23 04:37:29.360 CSPF failed: no route toward 17.0.0.7
96 Jul 23 04:37:29.360 CSPF: link down/deleted: 17.6.7.6(17.0.0.6:359)(17.0.0.6)->17.6.7.7(17.0.0.7:0)(17.0.0.7)
95 Jul 23 04:37:17.621 CSPF failed: no route toward 17.0.0.7
94 Jul 23 04:37:17.620 Deselected as active
93 Jul 23 04:37:17.620 CSPF failed: no route toward 17.0.0.7
92 Jul 23 04:37:17.620 Clear Call: CSPF computation failed
91 Jul 23 04:37:17.619 ResvTear received
90 Jul 23 04:37:17.619 17.1.3.1: Down
89 Jul 23 04:37:17.619 17.3.6.6: Session preempted
88 Jul 23 03:08:01.147 Selected as active path
87 Jul 23 03:08:01.146 Self-ping ended successfully
86 Jul 23 03:08:00.183 Up
85 Jul 23 03:08:00.183 Self-ping started
Standby RED-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Exclude: BLUE
Flap Count: 1
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 5000)
17.1.2.2 S 17.2.4.4 S 17.4.5.5 S 17.5.8.8 S 17.7.8.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.2.2(Label=299888) 17.2.4.4(Label=299888) 17.4.5.5(Label=299888) 17.5.8.8(Label=299904) 17.7.8.7(Label=3)
19 Jul 23 05:02:22.134 Self-ping ended successfully
18 Jul 23 05:02:21.944 Up
17 Jul 23 05:02:21.943 Self-ping started
16 Jul 23 05:02:21.943 Self-ping enqueued
15 Jul 23 05:02:21.943 Record Route: 17.1.2.2(Label=299888) 17.2.4.4(Label=299888) 17.4.5.5(Label=299888) 17.5.8.8(Label=299904) 17.7.8.7(Label=3)
14 Jul 23 05:02:21.889 LSP-ID: 11 created
13 Jul 23 05:02:21.889 Originate Call
12 Jul 23 05:02:21.889 CSPF: computation result accepted 17.1.2.2 17.2.4.4 17.4.5.5 17.5.8.8 17.7.8.7
11 Jul 23 05:00:55.139 Clear Call
10 Jul 23 04:59:27.189 Deselected as active: due to 'primary'
9 Jul 23 04:55:27.805 Selected as active path
8 Jul 23 04:55:27.804 Self-ping ended successfully
7 Jul 23 04:55:27.231 Up
6 Jul 23 04:55:27.231 Self-ping started
5 Jul 23 04:55:27.231 Self-ping enqueued
4 Jul 23 04:55:27.230 Record Route: 17.1.2.2(Label=299872) 17.2.4.4(Label=299872) 17.4.5.5(Label=299872) 17.5.8.8(Label=299888) 17.7.8.7(Label=3)
3 Jul 23 04:55:27.179 LSP-ID: 9 created
2 Jul 23 04:55:27.179 Originate Call
1 Jul 23 04:55:27.179 CSPF: computation result accepted 17.1.2.2 17.2.4.4 17.4.5.5 17.5.8.8 17.7.8.7
Created: Wed Jul 22 07:54:38 2026
Total 1 displayed, Up 1, Down 0
Egress LSP: 1 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 04. No constraints
Let’s see what happens if we have a Primary and Secondary path defined with constraints:
## Delete the constraints:
root@R1# delete protocols mpls label-switched-path TO-R7 secondary RED-PATH admin-group
root@R1# delete protocols mpls label-switched-path TO-R7 primary BLUE-PATH admin-group
root@R1# show | compare
[edit protocols mpls label-switched-path TO-R7 primary BLUE-PATH]
- admin-group include-any BLUE;
[edit protocols mpls label-switched-path TO-R7 secondary RED-PATH]
- admin-group exclude BLUE;
root@R1# commit
commit complete
### The Primary and Secondary have different paths:
root@R1# run show mpls lsp name TO-R7 extensive
Ingress LSP: 2 sessions
17.0.0.7
From: 17.0.0.1, State: Up, ActiveRoute: 0, LSPname: TO-R7, LSPid: 2
ActivePath: BLUE-PATH (primary)
LSPtype: Static Configured, Penultimate hop popping
LoadBalance: Random
Follow destination IGP metric
Encoding type: Packet, Switching type: Packet, GPID: IPv4
LSP Self-ping Status : Enabled
*Primary BLUE-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Flap Count: 9
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 3000)
17.1.3.3 S 17.3.6.6 S 17.6.7.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.3.3(Label=300032) 17.3.6.6(Label=300032) 17.6.7.7(Label=3)
145 Jul 23 08:43:58.240 Selected as active path: due to 'primary'
144 Jul 23 08:42:57.914 Self-ping ended successfully
143 Jul 23 08:42:57.073 Up
142 Jul 23 08:42:57.073 Self-ping started
141 Jul 23 08:42:57.073 Self-ping enqueued
140 Jul 23 08:42:57.073 Record Route: 17.1.3.3(Label=300032) 17.3.6.6(Label=300032) 17.6.7.7(Label=3)
139 Jul 23 08:42:57.041 LSP-ID: 13 created
138 Jul 23 08:42:57.041 Originate Call
137 Jul 23 08:42:57.041 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
[...]
Standby RED-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Flap Count: 3
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 6000)
17.1.2.2 S 17.2.4.4 S 17.4.5.5 S 17.5.6.6 S 17.6.8.8 S 17.7.8.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.2.2(Label=299968) 17.2.4.4(Label=299968) 17.4.5.5(Label=299968) 17.5.6.6(Label=300064) 17.6.8.8(Label=299984) 17.7.8.7(Label=3)
52 Jul 23 08:46:22.541 Self-ping ended successfully
51 Jul 23 08:46:22.370 Up
50 Jul 23 08:46:22.370 Self-ping started
49 Jul 23 08:46:22.370 Self-ping enqueued
48 Jul 23 08:46:22.370 Record Route: 17.1.2.2(Label=299968) 17.2.4.4(Label=299968) 17.4.5.5(Label=299968) 17.5.6.6(Label=300064) 17.6.8.8(Label=299984) 17.7.8.7(Label=3)
47 Jul 23 08:46:22.307 LSP-ID: 15 created
46 Jul 23 08:46:22.307 Originate Call
45 Jul 23 08:46:22.307 Clear Call
44 Jul 23 08:46:22.307 CSPF: computation result accepted 17.1.2.2 17.2.4.4 17.4.5.5 17.5.6.6 17.6.8.8 17.7.8.7
[...]
Created: Wed Jul 22 07:54:38 2026
Total 1 displayed, Up 1, Down 0
Egress LSP: 1 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
### Even if we disable the link between R5 and R8, we still have (partially) non overlapping paths:
root@R8# show | compare
[edit interfaces ge-0/0/1]
+ disable;
[edit]
root@R8# commit
commit complete
### Even with link R5-to-R8 down, JunOS still tries to find alternate paths:
root@R1# run show mpls lsp name TO-R7 extensive
Ingress LSP: 2 sessions
17.0.0.7
From: 17.0.0.1, State: Up, ActiveRoute: 0, LSPname: TO-R7, LSPid: 2
ActivePath: RED-PATH (secondary)
LSPtype: Static Configured, Penultimate hop popping
LoadBalance: Random
Follow destination IGP metric
Encoding type: Packet, Switching type: Packet, GPID: IPv4
Time remaining before reverting: 35
LSP Self-ping Status : Enabled
Primary BLUE-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Flap Count: 11
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 3000)
17.1.3.3 S 17.3.6.6 S 17.6.7.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.3.3(Label=300160) 17.3.6.6(Label=300144) 17.6.7.7(Label=3)
174 Jul 23 09:10:24.792 Deselected as active
173 Jul 23 09:10:08.786 Selected as active path
172 Jul 23 09:10:08.785 Self-ping ended successfully
171 Jul 23 09:10:08.391 Up
170 Jul 23 09:10:08.391 Self-ping started
169 Jul 23 09:10:08.391 Self-ping enqueued
168 Jul 23 09:10:08.391 Record Route: 17.1.3.3(Label=300160) 17.3.6.6(Label=300144) 17.6.7.7(Label=3)
167 Jul 23 09:10:08.358 Deselected as active
166 Jul 23 09:10:08.358 LSP-ID: 18 created
165 Jul 23 09:10:08.358 Originate Call
164 Jul 23 09:10:08.358 CSPF: computation result accepted 17.1.3.3 17.3.6.6 17.6.7.7
[...]
Standby RED-PATH State: Up
Priorities: 7 0
SmartOptimizeTimer: 180
Flap Count: 0
MBB Count: 0
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 6000)
17.1.2.2 S 17.2.4.4 S 17.4.5.5 S 17.5.6.6 S 17.6.8.8 S 17.7.8.7 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt 20=Node-ID):
17.1.2.2(Label=300016) 17.2.4.4(Label=300000) 17.4.5.5(Label=300000) 17.5.6.6(Label=300176) 17.6.8.8(Label=300016) 17.7.8.7(Label=3)
10 Jul 23 09:11:09.557 Deselected as active: due to 'primary'
9 Jul 23 09:10:24.792 Selected as active path
8 Jul 23 09:10:24.791 Self-ping ended successfully
7 Jul 23 09:10:24.659 Up
6 Jul 23 09:10:24.659 Self-ping started
5 Jul 23 09:10:24.659 Self-ping enqueued
4 Jul 23 09:10:24.658 Record Route: 17.1.2.2(Label=300016) 17.2.4.4(Label=300000) 17.4.5.5(Label=300000) 17.5.6.6(Label=300176) 17.6.8.8(Label=300016) 17.7.8.7(Label=3)
3 Jul 23 09:10:24.592 LSP-ID: 19 created
2 Jul 23 09:10:24.592 Originate Call
1 Jul 23 09:10:24.592 CSPF: computation result accepted 17.1.2.2 17.2.4.4 17.4.5.5 17.5.6.6 17.6.8.8 17.7.8.7
Created: Wed Jul 22 07:54:38 2026
Total 1 displayed, Up 1, Down 0
Egress LSP: 1 sessions
Total 0 displayed, Up 0, Down 0
Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0
Even with no constraints, JunOS will try to establish non overlapping paths.
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