Routing

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  • 1.  IS-IS route tagging

    Posted 11-26-2016 15:49

    I have a question as i am not able to find any documentation anywhere so far for what i'm looking for. 

     

    But, My question is, I Thought if you turned off traffic engineering on your is-is protocol that it would not tag any routes getting advertised out? 

     

    So i have a lo0 interface with an IPv4 and v6 address on there, When i have the policy applied and traffic engineering enabled on the connecting router P1 i see the appropriate tag coming in for the loopback ips. IE 

     

     

    root@P1# show protocols isis 
    export tag-lo0;
    interface ge-0/0/1.0;
    interface ge-0/0/2.0;
    interface ge-0/0/3.0;
    interface ge-0/0/4.0;
    interface ge-0/0/5.0;
    interface lo0.0 {
        passive;
    }
    
    [edit]
    root@P1# show policy-options policy-statement tag-lo0 
    from interface lo0.0;
    then {
        tag 200;
        accept;
    }

     

     

    root@PE12# run show route protocol isis | match tag
    1.1.1.1/32 [IS-IS/15] 03:53:00, metric 10, tag 200
    2001:db8::/128 *[IS-IS/15] 03:53:00, metric 10, tag 200

     

    Now, If i just disable traffic engineering on the is-is protocol, I still see a tag for the ipv6 route but not the ipv4. 

     

    root@PE12# run show route protocol isis | match tag
    2001:db8::/128 *[IS-IS/15] 04:00:59, metric 10, tag 200

     

    If i remove the policy from P1, It will not tag the ipv6 route. I was just wondering is this normal for the basic policy i have or does it appear to be a bug? 

     



  • 2.  RE: IS-IS route tagging
    Best Answer

    Posted 11-27-2016 03:25

    When ISIS Traffic Engineering is disabled, TLVs 22, 134, and 135 are suppressed from being sent

    Tags for IPv4 routes  are in TLV re in 135 (sub-TLV 1).

     

    For IPv6 routes the tags are in TLV 236. They are still present when you disable TE.

     

    In all the cases check the ISIS DB: show isis database extensive and you will see what information is being flooded.



  • 3.  RE: IS-IS route tagging

    Posted 11-27-2016 20:22

    Thanks, That clears it up for me. 

    I thought disabling traffic engineering turned off all tagging. 

     



  • 4.  RE: IS-IS route tagging

    Posted 12-03-2016 22:53

    Not sure if this will show up since it was marked solved, 

    But, i had another question related to this. 

     

    If i have both wide-metrics-only enabled, as well as traffic-engineering disabled, 

    This is suppost to supress tlvs 2,22,128,134,135 from being sent. 

     

    The documentation says it will basically be a loss of isis routing information for that level. 

     

    Since i configured it on both level 1 and level 2 i shouldn't see those tlvs, or supposidly anything. 

     

    Now, i do not see any routing information under the protocol isis, both the ipv4 and ipv6 table is blank. 

     

    But, if i monitor traffic on the downstream router, i still see advertisements for the ipv6 interfaces as well as the tag that is set on the export policy as seen below.

     

    IPv6 prefix: 2001:db9::1:2/127 Metric 10 Up
    IPv6 prefix: 2001:db9::1:4/127 Metric 10 Up
    IPv6 prefix: 2001:db9::1:0/127 Metric 10 Up
    IPv6 prefix: 2001:db9::1:6/127 Metric 10 Up
    IPv6 prefix: 2001:db9::1:8/127 Metric 10 Up
    IPv6 prefix: 2001:db8::/128 Metric 0 Up
    6 bytes of subtlvs
    Administrative tag 1: 200

     

    IPv6 reachability TLV #236, length: 139
    IPv6 prefix: 2001:db9::1:2/127, Distribution: up, Metric: 10, Internal
    IPv6 prefix: 2001:db9::1:4/127, Distribution: up, Metric: 10, Internal
    IPv6 prefix: 2001:db9::1:0/127, Distribution: up, Metric: 10, Internal
    IPv6 prefix: 2001:db9::1:6/127, Distribution: up, Metric: 10, Internal
    IPv6 prefix: 2001:db9::1:8/127, Distribution: up, Metric: 10, Internal
    IPv6 prefix: 2001:db8::/128, Distribution: up, Metric: 0, Internal, sub-TLVs present (6)
    32-Bit Administrative tag subTLV #1, length: 4, 0x000000c8 (=200)

     

    Does this make sence, or maybe its a bug in junosphere? Or am i missing a small detail somewhere?



  • 5.  RE: IS-IS route tagging

    Posted 12-05-2016 05:15

    You are still advertising IPv6 reachability information (TLVs #232 or #236). You can disable it

    set protocols isis no-ipv6-routing

     

    Or I think that you could do the opposite which is to allow only IPv6 (and although the "main" topology is non-existing)

    If you enable multi topology TLVs #229 I think you should see IPv6 routing information

    set protocols isis topologies ipv6-unicast

    Let me know if it worked.

     

     



  • 6.  RE: IS-IS route tagging

    Posted 12-05-2016 09:02

    So that explains why i am still seeing the TLVs, 

    But do you know why (Since its advertising those routes) it wouldn't be showing up in the route table on the downstream router?