ldp-tunneling with hidden route in table inet.3

[Boll Lu]

r1--rsvp--r2 r1-r2,enable ldp tunnel ,create extensive ldp neighbor, after enable ldp tunnel ,why generate hidden route in tabel inet.3 juniper@LAB# show protocols mpls label-switched-path r1-te to 10.20.11.1; ldp-tunneling; [edit logical-systems r1] juniper@LAB# run show route table inet.3 logical-system r1 inet.3: 1 destinations, 3 routes (1 active, 0 holddown, 1 hidden) + = Active Route, - = Last Active, * = Both 10.20.11.1/32 *[RSVP/7/1] 00:23:12, metric 10 > to 10.10.10.1 via ge-0/1/1.456, label-switched-path r1-te [LDP/9] 00:11:38, metric 1 > to 10.10.10.1 via ge-0/1/1.456, label-switched-path r1-te [edit logical-systems r1] juniper@LAB# run show route table inet.3 logical-system r1 hidden inet.3: 1 destinations, 3 routes (1 active, 0 holddown, 1 hidden) + = Active Route, - = Last Active, * = Both 10.20.11.1/32 [IS-IS] 00:11:46, metric 10 > to 10.10.10.1 via ge-0/1/1.456, label-switched-path r1-te [edit logical-systems r1] juniper@LAB# 

[Leo Gu]

Yes, im experiencing the same issue. Could any expert bring us any light on this question?

Thanks in advance.

Kind regards

Leo Gu

[erdems]

Hi all,

 This is a result of how ldp-tunneling is operating and is expected. Effectively, when ldp-tunneling is configured for a given RSVP LSP, JUNOS enables igp-shortcuts in the background. This is later on used to determine which RSVP LSPs can/will be used to tunnel for the LDP FEC. (seek answer to "What LDP FEC is behind each RSVP LSP?")

 However, since the configuration does not have igp-shortcuts knob enabled explicitly, JUNOS needs to make sure that they won't be used for other protocols (e.g. resolving a bgp next-hop), so they're shown as hidden in the CLI.

 Hope this clarifies it.

 Erdem

[Leo Gu]

Hi Erdems,

Many thanks for your answer which greatly helped me out of this issue.

May I ask a little more regarding the result of this kind of config?

If I just let those hidden routes resulted from "ldp-tunneling" to be there in inet.3, I mean if I do not config the "igp-shortcuts" explicitly under the [edit protocols ospf traffic-engineering shortcuts] hierarchy level, are there any negtive effects to the live network?

Thanks.

Kind regards

Leo Gu

[erdems]

Hey Leo,

 I'm happy to hear that.

 I may have not been entirely clear on my previous message. You do NOT need to use igp-shortcuts together with ldp-tunneling.

 The hidden routes you're seeing are harmless, think of them as a by-product due to the way ldp-tunneling works internally within JUNOS.

 Thanks,

 Erdem

[Leo Gu]

Thanks, Erdem.

Got it.

Really appreciate your help and replies.

BR

Leo Gu

[Leo Gu]

Hi Erdem,

Sorry but I have to re-open this thread as I am a bit confused with the "igp-shortcuts" you mentioned below.

=======================
This is a result of how ldp-tunneling is operating and is expected. Effectively, when ldp-tunneling is configured for a given RSVP LSP, JUNOS enables igp-shortcuts in the background. This is later on used to determine which RSVP LSPs can/will be used to tunnel for the LDP FEC. (seek answer to "What LDP FEC is behind each RSVP LSP?")
=======================

So could you pls kindly let me know which config is the correct one you meant when you mention the "igp-shortcuts"?
option 1)      set protocols mpls traffic-engineering bgp-igp
option 2)      set protocols isis/ospf traffic-engineering shortcuts

Thanks in advance.

BR

Leo Gu

[Surya]

Hi Leo,

See if this helps:

http://www.juniper.net/techpubs/en_US/junos10.0/information-products/topic-collections/config-guide-...

Regards

Surya Prakash

[Leo Gu]

Hi Surya,

Thanks for your link very much which really clears my confusion.

Thanks again.

Kind regards

Leo Gu