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Description

This article provides information about the effects of ISIS wide-metrics-only and traffic-engineering disable configuration options in Junos.

Symptoms

When ISIS wide-metrics-only is configured for a level or interface, TLV`s 2 and 128 are suppressed from being sent by the local router.
When ISIS Traffic Engineering is disabled, TLV`s 22, 134, and 135 are suppressed from being sent.
The combination of wide-metrics-only and traffic-engineering disable under protocols ISIS will result in the total loss of ISIS routing information for that level.
This combination suppresses TLV`s 2, 22, 128, 134, and 135 from being sent.

Solution

This topology will be used to portray the effects of the ISIS wide-metrics-only and traffic-engineering disable configuration options, with careful attention to the TLV`s 2, 22, 134, and 135. The effect of the configuration options on TLv`s 2, 22, 128, 134, and 135 will be individually evaluated.

Topology :

r1 and r2 are logical systems on the black router:

lo0 192.168.1.1                  lo0 192.168.1.2
     +---------+                      +---------+
     |         +----------------------+         |
     |  r1     |ge-0/2/0      ge-0/2/1|   r2    |
     +---------+10.1.2.1      10.1.2.2+---------+

TLV name 						TLV # 		PDU 

IS Reachability 				2 			L1 LSP, L2 LSP  < TLV : Old style TLV
Extended IS Reachability 			22 			L1 LSP, L2 LSP	< TLV : New style TLV
IP Internal Reachability 			128 			L1 LSP, L2 LSP  < TLV : Old style TLV
Traffic Engineering IP(Router ID)	134			L1 LSP, L2 LSP
Extended IP Reachability 			135 			L1 LSP, L2 LSP < TLV : New style TLV

Base configuration :

[edit]
lab@black# show logical-systems r1
Jun 23 15:27:35
interfaces {
    ge-0/2/0 {
        unit 0 {
            family inet {
                address 10.1.2.1/24;
            }
            family iso;
        }
    }
    lo0 {
        unit 1 {
            family inet {
                address 192.168.1.1/32;
            }
            family iso {
                address 49.0190.0192.0168.0101.00;
            }
        }
    }
}
protocols {
    isis {
        level 1;
        interface all {
            level 2 disable;
        }
    }
}
routing-options {
    router-id 192.168.1.1;
}

[edit]
lab@black# show logical-systems r2    
Jun 23 15:27:57
interfaces {
    ge-0/2/1 {
        unit 0 {
            family inet {
                address 10.1.2.2/24;
            }
            family iso;
        }
    }
    lo0 {
        unit 2 {
            family inet {
                address 192.168.1.2/32;
            }
            family iso {
                address 49.0190.0192.0168.0102.00;
            }
        }
    }
}
protocols {
    isis {
        level 1;
        interface all {
            level 2 disable;
        }
    }
}
routing-options {
    router-id 192.168.1.2;
}

Case 1 - Base configuration :

By default, traffic engineering is enabled in Junos for the ISIS protocols.

By default, Junos generates and accepts both wide and narrow style TLV`s.

Outputs :

[edit]
lab@black# run show isis adjacency logical-system r1     
Jun 23 15:29:46
Interface             System         L State        Hold (secs) SNPA
ge-0/2/0.0            black-r2       1  Up                    8  0:1b:c0:89:34:3f

-----

lab@black# run show isis route logical-system r1 
Jun 23 15:29:28
 IS-IS routing table             Current version: L1: 5 L2: 5
IPv4/IPv6 Routes
----------------
Prefix             L Version   Metric Type Interface    Via
192.168.1.2/32     1       5       10 int  ge-0/2/0.0   black-r2

ISIS database :

[edit]
lab@black# run show isis database logical-system r1 extensive level 1 
Jun 23 15:30:30
IS-IS level 1 link-state database:

black-r1.00-00 Sequence: 0x9, Checksum: 0x321, Lifetime: 1082 secs
   IS neighbor: black-r2.02                   Metric:       10
   IP prefix: 10.1.2.0/24                     Metric:       10 Internal Up
   IP prefix: 192.168.1.1/32                  Metric:        0 Internal Up

  Header: LSP ID: black-r1.00-00, Length: 147 bytes
    Allocated length: 1492 bytes, Router ID: 192.168.1.1
    Remaining lifetime: 1082 secs, Level: 1, Interface: 0
    Estimated free bytes: 1293, Actual free bytes: 1345
    Aging timer expires in: 1082 secs
    Protocols: IP, IPv6

  Packet: LSP ID: black-r1.00-00, Length: 147 bytes, Lifetime : 1198 secs
    Checksum: 0x321, Sequence: 0x9, Attributes: 0x3 <L1 L2>
    NLPID: 0x83, Fixed length: 27 bytes, Version: 1, Sysid length: 0 bytes
    Packet type: 18, Packet version: 1, Max area: 0

TLVs :

Area address: 49.0190 (3)
Speaks: IP
Speaks: IPV6
IP router id: 192.168.1.1
IP address: 192.168.1.1
Hostname: black-r1
IS neighbor: black-r2.02, Internal, Metric: default 10 < TLV : Old style TLV 
 IS extended neighbor: black-r2.02, Metric: default 10  < TLV : New style TLV 
 IP address: 10.1.2.1
Local interface index: 69,
 Remote interface index: 0
IP prefix: 10.1.2.0/24, Internal, Metric: default 10, Up
IP prefix: 192.168.1.1/32, Internal, Metric: default 0, Up
IP extended prefix: 10.1.2.0/24 metric 10 up
IP extended prefix: 192.168.1.1/32 metric 0 up
No queued transmissions

LSP capture :

TLVs 2,22,128,134,and 135 are all present.

lab@black# run monitor traffic interface ge-0/2/0 detail no-resolve
  
  15:36:58.015722 Out IS-IS, length 147
        L1 LSP, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
          lsp-id: 0192.0168.0101.00-00, seq: 0x0000000b, lifetime:  1198s
          chksum: 0xfe23 (correct), PDU length: 147, Flags: [ L1L2 IS ]
            Area address(es) TLV #1, length: 4
              Area address (length: 3): 49.0190
            Protocols supported TLV #129, length: 2
              NLPID(s): IPv4 (0xcc), IPv6 (0x8e)
            Traffic Engineering Router ID TLV #134, length: 4
              Traffic Engineering Router ID: 192.168.1.1
            IPv4 Interface address(es) TLV #132, length: 4
              IPv4 interface address: 192.168.1.1
            Hostname TLV #137, length: 8
              Hostname: black-r1
            IS Reachability TLV #2, length: 12
              IsNotVirtual
              IS Neighbor: 0192.0168.0102.02, Default Metric: 10, Internal
            Extended IS Reachability TLV #22, length: 27
              IS Neighbor: 0192.0168.0102.02, Metric: 10, sub-TLVs present (16)
                IPv4 interface address subTLV #6, length: 4, 10.1.2.1
                Link Local/Remote Identifier subTLV #4, length: 8, 0x00000045, 0x00000000
            IPv4 Internal Reachability TLV #128, length: 24
              IPv4 prefix:        10.1.2.0/24, Distribution: up, Metric: 10, Internal
              IPv4 prefix:     192.168.1.1/32, Distribution: up, Metric: 0, Internal
            Extended IPv4 Reachability TLV #135, length: 17
              IPv4 prefix:        10.1.2.0/24, Distribution: up, Metric: 10
              IPv4 prefix:     192.168.1.1/32, Distribution: up, Metric: 0

Case 2 - wide-metrics-only configured :

When wide-metrics-only is configured for a level, Junos suppresses the generation of narrow-style-metric TLV`s.

[edit]
lab@black# show logical-systems r1 protocols isis 
Jun 23 15:41:47
protocols {
    isis {
        level 1 wide-metrics-only; < Configured 
        interface all {
            level 2 disable;
        }
    }
}

Outputs :

Routing information :

[edit]
lab@black# run show isis route logical-system r1 
Jun 23 15:55:55
 IS-IS routing table             Current version: L1: 11 L2: 14
IPv4/IPv6 Routes
----------------
Prefix             L Version   Metric Type Interface    Via
192.168.1.2/32     1      11       10 int  ge-0/2/0.0   black-r2   

[edit]
lab@black# run show isis spf results logical-system r1    
Jun 23 16:06:16
 IS-IS level 1 SPF results:
Node             Metric     Interface         Via             SNPA
black-r2.00      10         ge-0/2/0.0       black-r2        0:1b:c0:89:34:3f
                 20         10.1.2.0/24
                 10         192.168.1.2/32        

[edit]
lab@black#

ISIS database :

[edit]
lab@black# run show isis database logical-system r1 level 1 extensive 
Jun 23 15:47:32
IS-IS level 1 link-state database:

black-r1.00-00 Sequence: 0xd, Checksum: 0xbd1c, Lifetime: 807 secs
   IS neighbor: black-r2.02                   Metric:       10
   IP prefix: 10.1.2.0/24                     Metric:       10 Internal Up
   IP prefix: 192.168.1.1/32                  Metric:        0 Internal Up

  Header: LSP ID: black-r1.00-00, Length: 107 bytes
    Allocated length: 1492 bytes, Router ID: 192.168.1.1
    Remaining lifetime: 807 secs, Level: 1, Interface: 0
    Estimated free bytes: 1329, Actual free bytes: 1385
    Aging timer expires in: 807 secs
    Protocols: IP, IPv6

  Packet: LSP ID: black-r1.00-00, Length: 107 bytes, Lifetime : 1198 secs
    Checksum: 0xbd1c, Sequence: 0xd, Attributes: 0x3 <L1 L2>
    NLPID: 0x83, Fixed length: 27 bytes, Version: 1, Sysid length: 0 bytes
    Packet type: 18, Packet version: 1, Max area: 0

TLVs :

Area address: 49.0190 (3)
    Speaks: IP
    Speaks: IPV6
    IP router id: 192.168.1.1
    IP address: 192.168.1.1
    Hostname: black-r1
    IS extended neighbor: black-r2.02, 
Metric: default 10 IP address: 10.1.2.1  
      Local interface index: 69, 
 Remote interface index: 0  
    IP extended prefix: 10.1.2.0/24 metric 10 up     IP  
extended prefix: 192.168.1.1/32 metric 0 up
  No queued transmissions

LSP capture :

Note :

Compared to the previous LSP output, TLV 2 and TLV 128 are missing, as the wide-metrics-only option is enabled. TLV`s corresponding to the narrow (old style) metric are suppressed

'Suppressed' indicates that the local router, which is configured for wide-metric, does not send TLVs 2 and 128; but accepts them, if received.

lab@black# run monitor traffic interface ge-0/2/0 detail no-resolve

15:41:01.016672 Out IS-IS, length 107
        L1 LSP, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
          lsp-id: 0192.0168.0101.00-00, seq: 0x0000000d, lifetime:  1198s
          chksum: 0xbd1c (correct), PDU length: 107, Flags: [ L1L2 IS ]
            Area address(es) TLV #1, length: 4
              Area address (length: 3): 49.0190
            Protocols supported TLV #129, length: 2
              NLPID(s): IPv4 (0xcc), IPv6 (0x8e)
            Traffic Engineering Router ID TLV #134, length: 4
              Traffic Engineering Router ID: 192.168.1.1
            IPv4 Interface address(es) TLV #132, length: 4
              IPv4 interface address: 192.168.1.1
            Hostname TLV #137, length: 8									
              Hostname: black-r1
            Extended IS Reachability TLV #22, length: 27
              IS Neighbor: 0192.0168.0102.02, Metric: 10, sub-TLVs present (16)
                IPv4 interface address subTLV #6, length: 4, 10.1.2.1
                Link Local/Remote Identifier subTLV #4, length: 8, 0x00000045, 0x00000000
            Extended IPv4 Reachability TLV #135, length: 17
              IPv4 prefix:        10.1.2.0/24, Distribution: up, Metric: 10
              IPv4 prefix:     192.168.1.1/32, Distribution: up, Metric: 0

Case 3 - traffic-engineering disabled :

lab@black# show logical-systems r1 protocols isis 
Jun 25 15:43:43
traffic-engineering disable; < Configured 
interface ge-0/2/0.0;
interface lo0.1;
interface all {
    level 2 disable;
}

Routing information :

[edit]
lab@black# run show isis route logical-system r1 
Jun 25 15:44:53
 IS-IS routing table             Current version: L1: 247 L2: 261
IPv4/IPv6 Routes
----------------
Prefix             L Version   Metric Type Interface    Via
192.168.1.2/32     1     247       10 int  ge-0/2/0.0   black-r2

ISIS database :

[edit]
lab@black# run show isis database extensive logical-system r1 
Jun 25 15:45:25
IS-IS level 1 link-state database:

black-r1.00-00 Sequence: 0x102, Checksum: 0xe439, Lifetime: 1087 secs
   IS neighbor: black-r2.02                   Metric:       10
   IP prefix: 10.1.2.0/24                     Metric:       10 Internal Up
   IP prefix: 192.168.1.1/32                  Metric:        0 Internal Up

  Header: LSP ID: black-r1.00-00, Length: 87 bytes
    Allocated length: 1492 bytes, Router ID: 0.0.0.0
    Remaining lifetime: 1087 secs, Level: 1, Interface: 0
    Estimated free bytes: 1345, Actual free bytes: 1405
    Aging timer expires in: 1087 secs
    Protocols: IP, IPv6

  Packet: LSP ID: black-r1.00-00, Length: 87 bytes, Lifetime : 1198 secs
    Checksum: 0xe439, Sequence: 0x102, Attributes: 0x3 <L1 L2>
    NLPID: 0x83, Fixed length: 27 bytes, Version: 1, Sysid length: 0 bytes
    Packet type: 18, Packet version: 1, Max area: 0

TLVs :

    Area address: 49.0190 (3)
    Speaks: IP
    Speaks: IPV6
    Hostname: black-r1
    IS neighbor: black-r2.02,Internal, 
Metric: default 10   
  IP prefix: 10.1.2.0/24, Internal, Metric: default 10, Up    
 IP prefix: 192.168.1.1/32, 
Internal, Metric: default 0, Up
  No queued transmissions

TED database :

[edit]
lab@black# run show ted database extensive logical-system r1 
Jun 25 15:45:56
TED database: 0 ISIS nodes 0 INET nodes

LSP capture :

TLVs 22,134, and 135 are suppressed and not sent; which indirectly suppresses the wide-style metric TLV`s.

[edit] lab@black# run monitor traffic interface ge-0/2/0 detail no-resolve 15:47:00.137512 Out IS-IS, length 87 L1 LSP, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0) lsp-id: 0192.0168.0101.00-00, seq: 0x00000104, lifetime: 1198s chksum: 0xe03b (correct), PDU length: 87, Flags: [ L1L2 IS ] Area address(es) TLV #1, length: 4 Area address (length: 3): 49.0190 Protocols supported TLV #129, length: 2 NLPID(s): IPv4 (0xcc), IPv6 (0x8e) Hostname TLV #137, length: 8 Hostname: black-r1 IS Reachability TLV #2, length: 12 IsNotVirtual IS Neighbor: 0192.0168.0102.02, Default Metric: 10, Internal IPv4 Internal Reachability TLV #128, length: 24 IPv4 prefix: 10.1.2.0/24, Distribution: up, Metric: 10, Internal IPv4 prefix: 192.168.1.1/32, Distribution: up, Metric: 0, Internal

Case 4 - wide-metrics-only is configured and traffic-engineering is disabled :

[edit]
lab@black# show logical-systems r1 protocols isis 
Jun 23 15:53:54
traffic-engineering disable; < Configured 
level 1 wide-metrics-only; < Configured 
interface all {
    level 2 disable;
}

Outputs :

Routing information :

[edit]
lab@black# run show isis route logical-system r1 
Jun 23 15:55:17
 IS-IS routing table Current version: L1: 10 L2: 12 < No routes 
[edit]
lab@black#

lab@black# run show isis spf results logical-system r1 
Jun 23 16:05:17
 IS-IS level 1 SPF results:
Node             Metric     Interface         Via             SNPA
black-r2.00      <disconnected>	
black-r1.00      0
  2 nodes

ISIS database :

[edit]
lab@black# run show isis database logical-system r1 extensive 
Jun 25 15:12:29
IS-IS level 1 link-state database:

black-r1.00-00 Sequence: 0xfb, Checksum: 0xd707, Lifetime: 1187 secs

  Header: LSP ID: black-r1.00-00, Length: 47 bytes
    Allocated length: 1492 bytes, Router ID: 0.0.0.0
    Remaining lifetime: 1187 secs, Level: 1, Interface: 0
    Estimated free bytes: 1381, Actual free bytes: 1445
    Aging timer expires in: 1187 secs
    Protocols: IP, IPv6

  Packet: LSP ID: black-r1.00-00, Length: 47 bytes, Lifetime : 1198 secs
    Checksum: 0xd707, Sequence: 0xfb, Attributes: 0x3 <L1 L2>
    NLPID: 0x83, Fixed length: 27 bytes, Version: 1, Sysid length: 0 bytes
    Packet type: 18, Packet version: 1, Max area: 0

TLVs :

Area address: 49.0190 (3)
    Speaks: IP
    Speaks: IPV6
    Hostname: black-r1
  No queued transmissions

LSP capture :

Note :

TLV`s 2, 22, 128, 134, and 135 are suppressed from being sent.
Essentially, no IP prefix and IS neighbor information are exchanged.
So, the routing information is not available.

lab@black# run monitor traffic interface ge-0/2/0 detail no-resolve

15:57:38.143900 Out IS-IS, length 47
        L1 LSP, hlen: 27, v: 1, pdu-v: 1, sys-id-len: 6 (0), max-area: 3 (0)
          lsp-id: 0192.0168.0101.00-00, seq: 0x00000012, lifetime:  1198s
          chksum: 0xab1d (correct), PDU length: 47, Flags: [ L1L2 IS ]
            Area address(es) TLV #1, length: 4
              Area address (length: 3): 49.0190
            Protocols supported TLV #129, length: 2
              NLPID(s): IPv4 (0xcc), IPv6 (0x8e)
            Hostname TLV #137, length: 8
              Hostname: black-r1