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  • 1.  ISIS L1/L2

    Posted 10-11-2012 03:32

     

    It’s true if we enable the wide-metric-only in all ISIS router, L2 routes will pass to L1 router ??



  • 2.  RE: ISIS L1/L2

    Posted 10-11-2012 04:10

    Hi,

    With wide-metrics-only enabled, ISIS level-1 external routes will be treated as internal routes and hence will be advertised to level-2 as internal routes. Otherwise, level-1 external routes will not be advertised to level-2.

     

    Level-2 routes will not be advertised to level-1 unless you configure leaking policy.

     

    Rgds

    Moses N 



  • 3.  RE: ISIS L1/L2

    Posted 10-11-2012 09:16

    So enabling wide-metric-only will allow only L1 external route to pass to L2 router

    And it has nothing to do with passing from L2 to L1 unless there is a leaking policy

     

     



  • 4.  RE: ISIS L1/L2
    Best Answer

    Posted 10-11-2012 14:10

    Yes. That's correct.



  • 5.  RE: ISIS L1/L2

    Posted 05-13-2013 23:19

    More knowledge shared.

     

    Wide Metric TLVs

    With the creation of the traffic engineering TLVs (22 and 135), the concept of limiting an interface cost to 6 bits was changed to allow for greater granularity and scalability. The new TLV use at least 24 bits to advertise the metric for a maximum interface metric of 16,777,215.

     

    The JUNOS software's default operation of IS-IS is to advertise both the small and wide metric TLVs in all LSPs. You can inform the local router to use only the wide metric TLVs with the wide-metrics-only command. The command is applied on a per-level basis and allows the local router to advertise larger metrics using only the extended TLVs. Note that wide metrics cannot differentiate between intenrnal and  external prefixes. As a result, the use of only wide metrics results in the automatic leaking of external prefixes from level 1 areas into level 2 areas. You can use routing policy to block the leaking of external prefixes into the backbone area if needed.


    #JNCIEandCCIE


  • 6.  RE: ISIS L1/L2

    Posted 05-16-2013 00:54

    Hello Sam,

    nice post thanks for providing useful information

     

    Best Regards

    Giuseppe

     



  • 7.  RE: ISIS L1/L2

    Posted 03-13-2022 19:16
    Hi,
    How 're about the IPv6 routes? Because in my lab, I saw the IPv6 routes in the table inet6 with "Level 1 external route", and store the ISIS database level 1.
    But they did not install to DB level 2. How can I  install/leak them to Level 2?

    root@R5> show route table inet6.0 2022:c:1::/60                        
    
    inet6.0: 18 destinations, 22 routes (18 active, 0 holddown, 0 hidden)
    + = Active Route, - = Last Active, * = Both
    
    2022:c:1:1::/64    *[IS-IS/160] 00:14:01, metric 20
                        > to fe80::205:86ff:fe71:de05 via ge-0/0/5.0
    2022:c:1:2::/64    *[IS-IS/160] 00:14:01, metric 20
                        > to fe80::205:86ff:fe71:de05 via ge-0/0/5.0
    2022:c:1:3::/64    *[IS-IS/160] 00:14:01, metric 20
                        > to fe80::205:86ff:fe71:de05 via ge-0/0/5.0
    2022:c:1:4::/64    *[IS-IS/160] 00:14:01, metric 20
                        > to fe80::205:86ff:fe71:de05 via ge-0/0/5.0
    2022:c:1:5::/64    *[IS-IS/160] 00:14:01, metric 20
                        > to fe80::205:86ff:fe71:de05 via ge-0/0/5.0
    
    root@R5> show isis database                                            
    IS-IS level 1 link-state database:
    LSP ID                      Sequence Checksum Lifetime Attributes
    R1.00-00                       0x181   0x71db      722 L1 L2
    R4.00-00                       0x1ab   0x3b72      698 L1
    R5.00-00                       0x13b   0x3bef     1183 L1 L2
    R8.00-00                       0x161   0x8bc0      899 L1
      4 LSPs
    
    IS-IS level 2 link-state database:
    LSP ID                      Sequence Checksum Lifetime Attributes
    R1.00-00                       0x189    0x505      663 L1 L2
    R2.00-00                       0x149   0x98a0     1190 L1 L2
    R3.00-00                       0x1c6   0xa224      834 L1 L2
    R5.00-00                       0x16f    0x426      480 L1 L2
    R6.00-00                       0x17c   0xcc2b      614 L1 L2
      5 LSPs
    
    root@R5> show isis database R4.00-00 extensive | match "level|ipv6"    
    IS-IS level 1 link-state database:
        Remaining lifetime: 695 secs, Level: 1, Interface: 333
        Protocols: IP, IPv6
        Speaks: IPV6
        IPv6 prefix: 2022:c:1:1::/64 Metric 10 External Up
        IPv6 prefix: 2022:c:1:2::/64 Metric 10 External Up
        IPv6 prefix: 2022:c:1:3::/64 Metric 10 External Up
        IPv6 prefix: 2022:c:1:4::/64 Metric 10 External Up
        IPv6 prefix: 2022:c:1:5::/64 Metric 10 External Up
    IS-IS level 2 link-state database:
    
    root@R5> show isis database R5.00-00 extensive | match "level|ipv6"    
    IS-IS level 1 link-state database:
        Remaining lifetime: 1178 secs, Level: 1, Interface: 0
        Protocols: IP, IPv6
        Speaks: IPV6
        IPv6 prefix: 2022:2022::ad2:105/128 Metric 0 Up
    IS-IS level 2 link-state database:
        Remaining lifetime: 474 secs, Level: 2, Interface: 0
        Protocols: IP, IPv6
        Speaks: IPV6
        IPv6 prefix: 2022:2022::ad2:105/128 Metric 0 Up
        IPv6 prefix: 2022:2022::ad2:101/128 Metric 20 Up​



  • 8.  RE: ISIS L1/L2

    Posted 10-17-2022 22:40
    With wide-metric-only enabled, L1 external routes are advertised to L2 as internal  routes. My question is whether I can stop advertising L1 external routes to L2 with wide-metric-only enabled ?

    thanks !!