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  • 1.  RSVP-TE bandwidth protection support

    Posted 26 days ago
    Edited by spuluka 25 days ago

    Hello guys!

    I've worked with RSVP-TE on Juniper devices and I know that devices support link protecion with aditional node protection, but I didn't find out anything about aditional bandwidth protection (Bandwidth protection desired:  0x08) as described on RFC 4090 on auto-bandwidth scenario. In summary, I'd like to know if Juniper devices support bandwidth protection to bypass LSPs on auto-bandwidth scenario.


    Note: my 
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    TARCISIO OLIVEIRA
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  • 2.  RE: RSVP-TE bandwidth protection support

    Posted 26 days ago

    The source of the bandwidth request to RSVP will be the path configuration for the LSP.  You choose the level of bandwidth request which can be the same for different for the primary and backup path.

    RSVP will then calculate the primary and backup path based on those requests and whatever over/under subscription is applied to the possible interfaces/links available for the request.



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    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP - Retired)
    http://puluka.com/home
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  • 3.  RE: RSVP-TE bandwidth protection support

    Posted 25 days ago

    Thanks @spuluka!

    I didn't explain well, actually I want to know about bypass LSP on auto-bandwidth scenario. In auto-bandwidth scenario the bandwidth of bypass LSPs is 0, because of that, there isn't bandwidth reservation of bypass LSP and there's a risk of saturation in case of primary path failure.

    Is there any resource that consider the bandwidth of bypass LSPs on auto-bandwidth scenario? Do Juniper devices support bandwidth protection (Bandwidth protection desired:  0x08) as described in RFC 4090?



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  • 4.  RE: RSVP-TE bandwidth protection support

    Posted 25 days ago

    Sorry for not being clear.  Yes, this is supported in Junos by using the bandwidth statement on the path as I mentioned.  You make this choice by configuring the bandwidth at the path level.

    For example, when you assign the same bandwidth for the primary and secondary path then both will consume allocated RSVP bandwidth as you note.  But when you declare zero as the bandwidth on the secondary path then no usage of the RSVP bandwidth occurs as you are looking for.

    You can even declare three paths when the primary and secondary declare the bandwidth and the third last resort path has zero bandwidth allocation so it can come up and be active even when the links are RSVP full.



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    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP - Retired)
    http://puluka.com/home
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  • 5.  RE: RSVP-TE bandwidth protection support
    Best Answer

    Posted 24 days ago

    Hi Tarcisio,

    Juniper routers support two ways of fast reroute protection just as described in RFC 4090, being one-to-one backup or facility backup (many-to-one), which could be used to different scenarios and purposes.

    In Junos naming, one-to-one backup is configured as using fast-reroute cli knob and uses "detour LSP" as protection while facility backup is configured using link-protection/node-link-protection cli knobs and uses "bypass LSP" as protection.

    Bypass LSP's are used to protect several or usually thousands of LSP's that cross a specific interface, so bandwidth is quite a complicated constraint. You can specify bandwidth to bypass LSP's among other options, and even in newer Junos version (23.4R1 and beyond) you can configure bypass lsp optimization based on unreserved bandwidth.

    Reference link: https://www.juniper.net/documentation/us/en/software/junos/mpls/topics/topic-map/link-protection-for-mpls.html



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    Eduardo Haro
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  • 6.  RE: RSVP-TE bandwidth protection support

    Posted 24 days ago
    Edited by TARCISIO OLIVEIRA 23 days ago

    @Eduardo Lopes de Haro, thanks for the answer!

    By default, on the facility backup with auto-bandwidth scenario, the sum of the individual LSPs bandwidth that is protected by a single bypass LSP isn't considered, right? Regard to LSP optimization based on the unreserved bandwidth, is it considered the interface with the highest unreserved bandwidth or something like that to create a bypass LSP? How it actually works?



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    TARCISIO OLIVEIRA
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  • 7.  RE: RSVP-TE bandwidth protection support

    Posted 23 days ago

    Hi Tarcisio,

    yes, default bandwidth value is zero if you don't configure it, here is the reference: https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/bandwidth-edit-protocols-rsvp.html

    The default approach of RSVP bypass produces a bypass method that optimizes traffic engineering (TE) metric. The Constrained Shortest Path First (CSPF) can optionally use a different approach to protect a link or a node by leveraging the computation based on unreserved bandwidths on (TE) links.

    So using this feature, CSPF would use unreserved bandwidth to compute the best path for the bypass LSP.



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    Eduardo Haro
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  • 8.  RE: RSVP-TE bandwidth protection support

    Posted 23 days ago

    @Eduardo Lopes de Haro

    It was very clear, thank you very much!!!



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