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  • 1.  Independent IGP Instances of IS-IS and SPRING

    Posted 05-11-2023 09:32

    Hello,

    I am looking for some help and if possible pointing to documentation or some source of information. 
    Trying to build a lab and test the ISIS instances, the configuration was snipped from  "How to Configure Multiple Independent IGP Instances of IS-IS". The basic part is working as expected and I decided to check if (and how) the source-packet-routing will be acting in this setup.

    The topology is very simple 4x ISIS peers, no fancy design and it's all was confirmed to work as expected in a classical ISIS setup.
    Once the configuration an all 4 devices were converted into isis-instance, the global/master process was deactivated.

    1st check - default/IGP setup is working as expected 
    2nd check - SPRING (again - same configuration working perfectly in a master ISIS instance)

    Source Packet Routing (SPRING): Enabled
        SRGB Config Range :
          SRGB Start-Label : 700000, SRGB Index-Range : 5000
        SRGB Block Allocation: Failure
          SRGB Start Index : 700000, SRGB Size : 5000, Label-Range: [ 700000, 704999 ]
        Node Segments: Enabled
          Ipv4 Index : 104, Ipv6 Index : 204

    So it's clear I have some issues with Lable allocation, but I am not sure how to go deeper and find out what could be the case.

    The debug log shows that I do advertise the needed SPRING info

    EX:

    May 11 13:20:11.115483 Receive LSP: LSP vMX2.00-00, type 135, len 36, count 219
    May 11 13:20:11.115540     IP unicast prefix: 1.1.1.2/32 metric 0 up
    May 11 13:20:11.115561       8 bytes of subtlvs
    May 11 13:20:11.115579       Node SID, Flags:0x40, Algo:SPF(0), Value:102

    Same time the Label allocation (under this configuration) is not working 
    EX: 

    set protocols isis-instance left interface all level 2 post-convergence-lfa
    set protocols isis-instance left interface all point-to-point
    set protocols isis-instance left source-packet-routing srgb start-label 700000
    set protocols isis-instance left source-packet-routing srgb index-range 5000
    set protocols isis-instance left source-packet-routing node-segment ipv4-index 104
    set protocols isis-instance left source-packet-routing node-segment ipv6-index 204
    set protocols isis-instance left level 1 disable
    set protocols isis-instance left backup-spf-options use-post-convergence-lfa maximum-backup-paths 3
    set protocols isis-instance left backup-spf-options use-source-packet-routing

    I rebooted (after the configuration changed from MAIN to INSTANCE) all involved devices, so there should be no issues with this.

    Any help will be much appreciated. 

    Thank you in advance,

    Andrei



    ------------------------------
    Andrei Cebotareanu
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  • 2.  RE: Independent IGP Instances of IS-IS and SPRING

    Posted 05-17-2023 06:52
    Edited by Andrei Cebotareanu 05-17-2023 06:53

    Just a short update on this.

    I was doing more tests (this time a simple "reverse engineering") and found out that it works with the following conditions:

    1. The main ISIS process (instance) should be enabled (no interfaces, levels etc needed, just as a process)
    2. The SRGB must be enabled and the range, should be the same as you are planning to use under the relevant instance (interesting point, I was testing with the bigger range - to check if I could have a big one on the master and specific one under the different instances... it did not work in this way...)
    3. Once you have the above in place - it will start working as expected.

    Still an open topic (maybe somebody may have needed information)
    - How to debug the mpls label allocation?
    - How to debug the isis in regards to label allocation? 

    PS: 
    As I mentioned in the 1st post, it looks all be related to mpls label allocation. 
    Without the "main ISIS instance" the MPLS labels are not allocated to the ISIS process, causing the ISIS-instance to be unable to use it.

    run show mpls label usage
    Label space Total   Available        Applications
    LSI         994984  994980 (100.00%) BGP/LDP VPLS with no-tunnel-services, BGP L3VPN with vrf-table-label
    Block       994984  994980 (100.00%) BGP/LDP VPLS with tunnel-services, BGP L2VPN
    Dynamic     994984  994980 (100.00%) RSVP, LDP, PW, L3VPN, RSVP-P2MP, LDP-P2MP, MVPN, EVPN, BGP
    Static      48576   48576  (100.00%) Static LSP, Static PW
    Effective Ranges
    Range name  Shared with Start   End
    Dynamic     16      799999
    Dynamic     805000  999999
    Static      1000000 1048575
    SRGB        800000  804999   ISIS
    Configured Ranges
    Range name  Shared with Start   End
    Dynamic     16      799999
    Dynamic     805000  999999
    Static      1000000 1048575
    SRGB        800000  804999   ISIS 





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    Andrei Cebotareanu
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  • 3.  RE: Independent IGP Instances of IS-IS and SPRING

    Posted 05-22-2023 02:54

    Next curiosity/unclarity 

    While isis-instances are working (as IGP) very straightforwardly, once I am trying to put on top of it some MPLS/SR and etc it takes me out of my "comfort zone".  Can somebody clarify for me the following
    • How can one instruct the ISIS-instance to populate the TED database (for now all information in TED is only sources from "main isis task")
    • Is there any documentation that can explain how the ISIS instances should work in regard to MPLS/SR integration (SRING support)
    • Is there any docu/information that can explain how the SPRING/TED information can be exported/imported between different ISIS tasks
    Thank you in advance


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    Andrei Cebotareanu
    ------------------------------