LDP route in inet.3 flapped

[balanar.malam@gmail…]

Hi all,

I saw LDP route in inet.3 is flapped 2days ago but the same route for RSVP protocols in inet.3 is not flapped at that time, but was flapped at 2 weeks ago. When I see the route in inet.0 table has the same age with the RSVP route in inet.3. I dont see any link flapped along the paths from the router to the destination route. Also, I see the FEC age in the LDP database session is not getting flapped in the same time with the LDP route in inet.3:

show route table inet.0 112.215.48.2/32

inet.0: 2456 destinations, 2456 routes (2425 active, 0 holddown, 31 hidden)
Restart Complete
+ = Active Route, - = Last Active, * = Both

112.215.48.2/32    *[IS-IS/18] 2w0d 21:50:42, metric 12
                    > to 121.52.0.58 via ae1.0


show route table inet.3 112.215.48.2/32

inet.3: 2407 destinations, 3066 routes (543 active, 0 holddown, 2406 hidden)
Restart Complete
+ = Active Route, - = Last Active, * = Both

112.215.48.2/32    *[RSVP/7/1] 2w0d 21:36:07, metric 12
                    > to 121.52.0.58 via ae1.0, label-switched-path
xxx
                      to 121.52.11.17 via xe-1/0/0.0, label-switched-path
Bypass->121.52.0.58->112.52.43.58
                    [LDP/9] 2d 21:40:50, metric 12
                    > to 121.52.0.58 via ae1.0, label-switched-path
xxx
                      to 121.52.11.17 via xe-1/0/0.0, label-switched-path
xxx


show ldp database session 112.215.48.2 extensive                    
            
Input label database, 202.152.246.1:0--112.215.48.2:0
      3     112.215.48.2/32
            State: Active
            Age: 5w1d 6:06:08
Output label database, 202.152.246.1:0--112.215.48.2:0
 539975     112.215.48.2/32
            State: Active
            Age: 2w0d 21:54:10

Any clue what is happened and what is the trigger of the LDP route getting flapped?

Thanks.

[Surya]

Hi,

I believe you have the LDP session over the RSVP tunnel (ldp-tunneling). If so, the difference in time could be due to bypass-lsp flap. Please check if there was no link flap in the bypass path too.

In my test, I flapped the bypass link and I could see the difference in timestamp similar as yours one, though the LDP session and database timestamp matches with ISIS and RSVP.

[edit]
suryak@juniper1# run show route 2.2.2.2                                             

inet.0: 45 destinations, 45 routes (43 active, 0 holddown, 2 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32         *[IS-IS/15] 00:14:07, metric 10
                    > to 10.8.11.2 via so-3/0/0.0

inet.3: 3 destinations, 5 routes (1 active, 0 holddown, 3 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32         *[RSVP/7/1] 00:13:53, metric 10
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path Bypass->10.8.11.2
                    [LDP/9] 00:01:55, metric 1
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path ice-hun

[edit]
suryak@juniper1# run show ldp session 2.2.2.2 extensive | grep "Address|Up for"     
Address: 2.2.2.2, State: Operational, Connection: Open, Hold time: 28
  Local address: 1.1.1.1, Remote address: 2.2.2.2
  Up for 00:14:13
  Next-hop addresses received:
Address                   1             1             0             0
Address withdraw          0             0             0             0

[edit]
suryak@juniper1# run show ldp database extensive session 2.2.2.2
Input label database, 1.1.1.1:0--2.2.2.2:0
  Label     Prefix
 300208     1.1.1.1/32
            State: Active
            Age: 14:22
      3     2.2.2.2/32
            State: Active
            Age: 14:23

Output label database, 1.1.1.1:0--2.2.2.2:0
  Label     Prefix
      3     1.1.1.1/32
            State: Active
            Age: 14:23
 299776     2.2.2.2/32
            State: Active
            Age: 14:12

[edit]
suryak@juniper1# run show rsvp session ingress detail | grep "LSPname|Time"         
  LSPname: ice-hun, LSPpath: Primary
  Time left:    -, Since: Mon May  7 15:45:29 2012
  LSPname: Bypass->10.8.11.2
  Time left:    -, Since: Mon May  7 15:57:05 2012

Regards

Surya

[balanar.malam@gmail…]

Hi Surya,

Thanks for your valuable information. now checking on my router, the LDP route for the prefix is like below:

> show route table inet.3 112.215.48.2

inet.3: 2419 destinations, 3077 routes (542 active, 0 holddown, 2418 hidden)
Restart Complete
+ = Active Route, - = Last Active, * = Both

112.215.48.2/32    *[RSVP/7/1] 2d 10:05:21, metric 12
                    > to 121.52.0.58 via ae1.0, label-switched-path xxx
                      to 121.52.0.50 via ae0.0, label-switched-path Bypass->121.52.0.58->112.52.43.58
                    [LDP/9] 17:19:35, metric 12
                    > to 121.52.0.58 via ae1.0, label-switched-path xxx
                      to 121.52.0.50 via ae0.0, label-switched-path xxx

The bypasss LSP Bypass->121.52.0.58->112.52.43.58 itself  has flapped time as below:

> show rsvp session name Bypass->121.52.0.58->112.52.43.58 ingress detail | match "LSPname|Time"
  LSPname: Bypass->121.52.0.58->112.52.43.58
  Time left:    -, Since: Mon May  7 23:57:21 2012

If I look the time difference between current time and the LDP routes, so it will be more match with below bypass LSP:

> show rsvp session name Bypass->121.52.11.17->121.52.0.33 ingress detail | match "LSPname|Time"
  LSPname: Bypass->121.52.11.17->121.52.0.33
  Time left:    -, Since: Wed May  9 03:32:59 2012

my question is, will the LDP route will flapped if any bypass LSP flapped but actually the bypass LSP is not used by the LDP route path as protection/bypass LSP? I hope you get what I mean :-)

Thanks,

[balanar.malam@gmail…]

Here is the system uptime at that time:

> show system uptime
Current time: 2012-05-09 20:56:29 WIT
System booted: 2011-07-26 21:37:06 WIT (41w0d 23:19 ago)
Protocols started: 2011-07-26 21:38:18 WIT (41w0d 23:18 ago)
Last configured: 2012-04-13 03:01:46 WIT (3w5d 17:54 ago) by hendrilti
 8:56PM  up 287 days, 23:19, 2 users, load averages: 0.30, 0.23, 0.17

Thanks,

[Surya]

Hi,

In short it is not a LDP flap :-)

Sorry I have to give you a little background, please bear with me.

When user enables LDP-TUNNELING, you would see the IGP paths in inet.3 table which uses RSVP LSP as nexthop. This is done as LDP relies on IGP for path computation and we want LDP to take RSVP LSP as nexthop. As this is mainly used by LDP you would see these IGP paths as hidden routes in inet.3 table.

Whenever there is change in the RSVP LSP including bypass, these IGP paths goes through SPF computation and hence the route would be updated. This would make LDP also to get updated which causes LDP to reset the time.

<<< BEFORE BYPASS FLAP >>>
[edit]
suryak@latte# run show route 2.2.2.2

inet.0: 45 destinations, 45 routes (43 active, 0 holddown, 2 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32         *[IS-IS/15] 00:31:33, metric 10
                    > to 10.8.11.2 via so-3/0/0.0

inet.3: 3 destinations, 5 routes (1 active, 0 holddown, 3 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32         *[RSVP/7/1] 00:31:22, metric 10
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path Bypass->10.8.11.2
                    [LDP/9] 00:30:29, metric 1
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path ice-hun

[edit]
suryak@latte# run show route table inet.3 hidden    

inet.3: 3 destinations, 5 routes (1 active, 0 holddown, 3 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32          [IS-IS] 00:30:22, metric 10
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path Bypass->10.8.11.2



<<< AFTER BYPASS FLAP >>

[edit]
suryak@latte# run show route 2.2.2.2                

inet.0: 45 destinations, 45 routes (43 active, 0 holddown, 2 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32         *[IS-IS/15] 00:33:20, metric 10
                    > to 10.8.11.2 via so-3/0/0.0

inet.3: 3 destinations, 5 routes (1 active, 0 holddown, 3 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32         *[RSVP/7/1] 00:33:09, metric 10
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path Bypass->10.8.11.2
                    [LDP/9] 00:00:42, metric 1
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path ice-hun

[edit]
suryak@latte# run show route table inet.3 hidden    

inet.3: 3 destinations, 5 routes (1 active, 0 holddown, 3 hidden)
+ = Active Route, - = Last Active, * = Both

2.2.2.2/32          [IS-IS] 00:00:46, metric 10
                    > via so-3/0/0.0, label-switched-path ice-hun
                      to 10.8.1.2 via ge-5/0/2.0, label-switched-path Bypass->10.8.11.2

Regards

Surya