Description

Pre-upgrade output looks like this: Junos 17.4R2-S11

dev01-re0> show route summary logical-system all
inet.0: 1013718 destinations, 3053767 routes (1013707 active, 0 holddown, 11 hidden)
Direct: 11 routes, 10 active
Local: 10 routes, 10 active
OSPF: 1735 routes, 1735 active <<<-----
BGP: 3051826 routes, 1011948 active
Static: 3 routes, 3 active
RSVP: 178 routes, 0 active
LDP: 4 routes, 1 active

inet.3: 1769 destinations, 1964 routes (1769 active, 0 holddown, 0 hidden)
OSPF: 1728 routes, 1560 active.  <<<<-----------
RSVP: 168 routes, 168 active
LDP: 3 routes, 3 active
Tunnel: 65 routes, 38 active

labroot@jtac-mx204-r2038> show route 192.168.1.4   <<--- R3 lo0.0 interface IP 

inet.0: 3021 destinations, 3022 routes (3021 active, 0 holddown, 0 hidden)
@ = Routing Use Only, # = Forwarding Use Only
+ = Active Route, - = Last Active, * = Both

192.168.1.4/32     @[OSPF/10] 21:15:03, metric 2
                    > to 192.168.10.2 via xe-0/1/2.0, label-switched-path TO-R3
                   #[RSVP/7/1] 21:15:03, metric 2
                    > to 192.168.10.2 via xe-0/1/2.0, label-switched-path TO-R3

inet.3: 7 destinations, 8 routes (7 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

192.168.1.4/32     *[RSVP/7/1] 21:15:03, metric 2
                    > to 192.168.10.2 via xe-0/1/2.0, label-switched-path TO-R3
                    [OSPF/10] 21:15:03, metric 2
                    > to 192.168.10.2 via xe-0/1/2.0, label-switched-path TO-R3


Post-upgrade output looks like this: Junos 21.4R3-S5.4

dev02-re0> show route summary logical-system all
inet.0: 1013285 destinations, 3052479 routes (1013273 active, 1 holddown, 11 hidden)
Direct: 11 routes, 10 active
Local: 9 routes, 9 active
OSPF: 1735 routes, 1735 active.  <<< ----
BGP: 3050540 routes, 1011515 active
Static: 3 routes, 3 active
RSVP: 178 routes, 0 active
LDP: 3 routes, 1 active

inet.3: 208 destinations, 235 routes (208 active, 0 holddown, 0 hidden). <<< -- route in the inet.3
RSVP: 168 routes, 168 active
LDP: 2 routes, 2 active
Tunnel: 65 routes, 38 active


labroot@jtac-mx204-r2048> show route 192.168.1.2   << -- R1 lo0.0 ip 

inet.0: 3021 destinations, 3024 routes (3021 active, 0 holddown, 0 hidden)
@ = Routing Use Only, # = Forwarding Use Only
+ = Active Route, - = Last Active, * = Both

192.168.1.2/32     @[OSPF/10] 21:16:21, metric 2
                    >  to 192.168.11.1 via xe-0/1/2.0, label-switched-path TO-R1
                   #[RSVP/7/1] 21:16:21, metric 2
                    >  to 192.168.11.1 via xe-0/1/2.0, label-switched-path TO-R1

inet.3: 3 destinations, 3 routes (3 active, 0 holddown, 0 hidden).  <<<< -- OSP shortcut route not in the inet.3 [why change in behaviour]
+ = Active Route, - = Last Active, * = Both

192.168.1.2/32     *[RSVP/7/1] 21:16:21, metric 2
                    >  to 192.168.11.1 via xe-0/1/2.0, label-switched-path TO-R1

Solution

As per the engineering team this is expected. changes are made through PR-1561207 [single-source-commit] - Output difference on "show route table inet.3" CLI in 16.2R1 with traffic-engineering shortcuts and bgp-igp-both-ribs enabled.

Snipped from PR-1561207

By default, OSPF routes will be inet.0 only.

When OSPF TE shortcuts are enabled, LSP shortcuts will be added to inet.3.
When bgp-igp-both-ribs config enabled then if OSPF adds LSP shortcuts to inet.3 that's where we are seeing duplicate LSP in inet.3 and same is removed as part of fix.

Regarding the document it holds true when only OSPF TE shortcuts are enabled. If bgp-igp-both-ribs/mpls-forwarding are enabled then behaviour varies.

PR Link : https://gnats.juniper.net/web/default/1561207#scope_tab

Modification History

2024-01-16 : Article Created

Related Information

https://gnats.juniper.net/web/default/1561207#scope_tab

https://www.juniper.net/documentation/us/en/software/junos/ospf/topics/topic-map/configuring-ospf-support-for-traffic-engineering.html