IS-IS Lab 2 Verification

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Image requirements:
 Cisco IOSv (vios-adventerprisek9-m.vmdk.SPA.156-2.T)


Introduction:
Learn the output of different show commands for the IS-IS routing protocol. One by one you will explore some valuable information that will allow you to understand better this link-state protocol. 


Nodes Access: 
Enable:       cisco 
Username:  cisco 
Password:   cisco 


IS-IS Verification commands:

Core1#show  isis neighbors  
System Id       Type Interface     IP Address      State Holdtime Circuit Id
Core2              L1   Gi0/2         10.0.0.6        UP    8        Core2.02          
Core2              L2   Gi0/2         10.0.0.6        UP    9        Core2.02          
Core3              L1   Gi0/1         10.0.0.2        UP    24       Core1.01          
Core3              L2   Gi0/1         10.0.0.2        UP    21       Core1.01          
Core4              L1   Gi0/3         10.0.0.10       UP    7        Core4.03          
Core4              L2   Gi0/3         10.0.0.10       UP    9        Core4.03          
ENR1              L1   Gi0/4         10.0.1.2        UP    22       Core1.04          
ENR1              L2   Gi0/4         10.0.1.2        UP    29       Core1.04          
Core1#


* There are three neighbors in the output, two entries per neighbor are for each type of IS Database "level-1" and "level-2", you can derive this from the "Type" column. 

* The "Interface" column shows a local interface where neighbor adjacency has been established. 

* The "IP address" column identifies the layer 3 address of the neighbor. 

* The "State UP" refers that IS-IS adjacency has been set up and link-state database synchronized.  

* The "Holdtime" indicates in seconds how much time left before declaring IS-IS neighborship down.  

* The "Circuit Id" identifies the IS-IS interface.  



Core1#show  isis protocol
IS-IS Router: <Null Tag>
  System Id: 0000.0000.C001.00  IS-Type: level-1-2
  Manual area address(es):
        49.a001
  Routing for area address(es):
        49.a001
  Interfaces supported by IS-IS:
        GigabitEthernet0/4 - IP
        GigabitEthernet0/3 - IP
        GigabitEthernet0/2 - IP
        GigabitEthernet0/1 - IP
        Loopback0 - IP
  Redistribute:
    static (on by default)
  Distance for L2 CLNS routes: 110
  RRR level: none
  Generate narrow metrics: level-1-2
  Accept narrow metrics:   level-1-2
  Generate wide metrics:   none
  Accept wide metrics:     none
Core1#

*This show command is like "show ip protocol" but only for IS-IS, a lot of valuable information could be derived from this output, it shows you System Id, Area Id, interfaces participating in the IS-IS process, redistribution from routing sources, IS-Type is a very important parameter to check when you missing entries in the database, Administrative Distance for IS-IS is 115, finally you verify what type of metrics supported. Almost forgot to mention, at the top of the output "IS-IS Router:" line says: <Null Tag> which indicates that default IS-IS topology is used. You can configure multiple topologies to reduce the size of the IS-IS database or to differentiate between routed protocols, for example by default IS-IS uses a single database for both IPv4 and IPv6 if your design requires separate databases for each of routed protocol simply configure IS-IS with two different tags. 


Core1#show  isis hostname
Level  System ID      Dynamic Hostname  (notag)
     * 0000.0000.C001 Core1
 2     0000.0000.C002 Core2
 2     0000.0000.C003 Core3
 2     0000.0000.C004 Core4
 2     0000.0000.E001 ENR1
 2     0000.0000.ED01 EDR1
 2     0000.0000.ED02 EDR2
Core1#

* Useful show command to verify real numerical System Ids associated with host-names of the IS-IS participating routers.


Core1#show  isis topology 
IS-IS TID 0 paths to level-1 routers
System Id            Metric     Next-Hop             Interface   SNPA
Core1                --
Core2                10         Core2                Gi0/2       fa16.3e92.c846
Core3                10         Core3                Gi0/1       fa16.3e37.b956
Core4                10         Core4                Gi0/3       fa16.3eb9.63a6
ENR1                 10         ENR1                 Gi0/4       fa16.3e16.4245
EDR1                 20         Core3                Gi0/1       fa16.3e37.b956
                                Core4                Gi0/3       fa16.3eb9.63a6
EDR2                 20         Core3                Gi0/1       fa16.3e37.b956
                                Core4                Gi0/3       fa16.3eb9.63a6


IS-IS TID 0 paths to level-2 routers
System Id            Metric     Next-Hop             Interface   SNPA
Core1                --
Core2                10         Core2                Gi0/2       fa16.3e92.c846
Core3                10         Core3                Gi0/1       fa16.3e37.b956
Core4                10         Core4                Gi0/3       fa16.3eb9.63a6
ENR1                 10         ENR1                 Gi0/4       fa16.3e16.4245
EDR1                 20         Core3                Gi0/1       fa16.3e37.b956
                                Core4                Gi0/3       fa16.3eb9.63a6
EDR2                 20         Core3                Gi0/1       fa16.3e37.b956
                                Core4                Gi0/3       fa16.3eb9.63a6
Core1#


* This is a very useful command especially when you are not familiar with topology of the IS-IS domain, also it is good to keep this output in your baseline documentation, you always could quickly determine which router is not participating in the IS-IS process. The command shows you all routers participating in the routing process, the metric to the neighboring routers and its next-hop to reach them as well outgoing interface and MAC address of the neighbors' interfaces. In this particular output, you can notice that there are two parts, one for Level-1 and another for level-2 it because the router is operating as an L1/L2 IS-type router. There are 7 routers in the topology, pay attention to the routers EDR1 and EDR2 they are both have the metric of 20 and reachable via Core3 and Core4 routers using outgoing interfaces g0/1 and g0/3.


Core1#show  isis  spf-log
  TID 0 level 1 SPF log
  When   Duration  Nodes  Count    First trigger LSP   Triggers
02:50:06       0      1      4          Core1.00-00  PERIODIC NEWADJ NEWLSP TLVCODE CLNSBACKUP
02:49:56       3      6      8          Core2.02-00  NEWADJ NEWLSP TLVCONTENT
02:49:43       3     14     13          Core1.00-00  NEWADJ NEWLSP TLVCONTENT
02:49:33       6     19     12           EDR1.00-00  NEWADJ NEWLSP TLVCONTENT
02:35:08       2     19      1                       PERIODIC CLNSBACKUP
02:20:08       2     19      1                       PERIODIC CLNSBACKUP
02:05:08       2     19      1                       PERIODIC CLNSBACKUP
01:50:08       2     19      1                       PERIODIC CLNSBACKUP
01:35:08       2     19      1                       PERIODIC CLNSBACKUP
01:20:08       2     19      1                       PERIODIC CLNSBACKUP
01:05:08       2     19      1                       PERIODIC CLNSBACKUP
00:50:08       2     19      1                       PERIODIC CLNSBACKUP
00:35:08       2     19      1                       PERIODIC CLNSBACKUP
00:20:08       2     19      1                       PERIODIC CLNSBACKUP
00:05:08       2     19      1                       PERIODIC CLNSBACKUP

 TID 0 level 2 SPF log
  When   Duration  Nodes  Count    First trigger LSP   Triggers
02:50:06       0      1      2          Core1.00-00  PERIODIC NEWLSP CLNSBACKUP
02:49:56       6      6     10          Core1.00-00  NEWADJ NEWLSP TLVCODE TLVCONTENT
02:49:46       3     11     10          Core3.00-00  NEWADJ NEWLSP TLVCONTENT
02:49:36      10     19     17          Core4.00-00  NEWADJ NEWLSP TLVCONTENT
02:49:26       3     19      2          Core2.00-00  TLVCONTENT
02:35:08       2     19      1                       PERIODIC CLNSBACKUP
02:20:08       2     19      1                       PERIODIC CLNSBACKUP
02:05:08       2     19      1                       PERIODIC CLNSBACKUP
01:50:08       2     19      1                       PERIODIC CLNSBACKUP
01:35:08       2     19      1                       PERIODIC CLNSBACKUP
01:20:08       2     19      1                       PERIODIC CLNSBACKUP
01:05:08       2     19      1                       PERIODIC CLNSBACKUP
00:50:08       2     19      1                       PERIODIC CLNSBACKUP
00:35:08       2     19      1                       PERIODIC CLNSBACKUP
00:20:08       2     19      1                       PERIODIC CLNSBACKUP
00:05:08       2     19      1                       PERIODIC CLNSBACKUP

* This particular command reveals how often the SPF algorithm runs, check it if you suspect that there are some instabilities on the network, like flapping interfaces, for example, use it in conjunction with these debug commands:

Core1# debug isis spf-triggers
Core1# debug isis spf-events
Core1# debug isis spf-statistics 


Core1#show  isis database 
 IS-IS Level-1 Link State Database:
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime/Rcvd      ATT/P/OL
Core1.00-00         * 0x00000012   0x9C27                 628/*         0/0/0
Core1.01-00         * 0x0000000F   0xA35D                1051/*         0/0/0
Core1.04-00         * 0x0000000E   0x617F                 555/*         0/0/0
Core2.00-00           0x00000013   0x0E9B                1052/1199      0/0/0
Core2.01-00           0x0000000F   0xC23B                1035/1199      0/0/0
Core2.02-00           0x0000000E   0x728E                 484/1199      0/0/0
Core2.03-00           0x0000000F   0x9B61                 860/1199      0/0/0
Core2.04-00           0x0000000E   0x6777                 645/1199      0/0/0
Core3.00-00           0x00000012   0x42B2                 610/1199      0/0/0
Core3.02-00           0x0000000F   0xC139                 721/1199      0/0/0
Core3.05-00           0x0000000E   0xB815                 752/1199      0/0/0
Core4.00-00           0x00000012   0x03BA                1131/1199      0/0/0
Core4.03-00           0x0000000E   0x7784                 510/1199      0/0/0
ENR1.00-00            0x00000010   0x4327                1036/1199      0/0/0
EDR1.00-00            0x00000010   0x9130                 896/1198      0/0/0
EDR1.01-00            0x0000000E   0x5A4D                 683/1198      0/0/0
EDR1.02-00            0x0000000F   0x6A3A                1154/1198      0/0/0
EDR2.00-00            0x00000011   0x4298                1181/1198      0/0/0
EDR2.02-00            0x0000000F   0x7032                1001/1198      0/0/0
IS-IS Level-2 Link State Database:
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime/Rcvd      ATT/P/OL
Core1.00-00         * 0x00000015   0x684F                 554/*         0/0/0
Core1.01-00         * 0x0000000F   0x3356                 860/*         0/0/0
Core1.04-00         * 0x0000000F   0xEE79                1169/*         0/0/0
Core2.00-00           0x00000016   0x3C77                 520/1199      0/0/0
Core2.01-00           0x0000000F   0x5234                1132/1199      0/0/0
Core2.02-00           0x0000000E   0x0287                 552/1199      0/0/0
Core2.03-00           0x0000000F   0x2B5A                1040/1199      0/0/0
Core2.04-00           0x0000000E   0xF670                 580/1199      0/0/0
Core3.00-00           0x00000016   0x0865                 488/1199      0/0/0
Core3.02-00           0x0000000F   0x5132                1069/1199      0/0/0
Core3.05-00           0x0000000E   0x480E                 597/1199      0/0/0
Core4.00-00           0x00000015   0x9E9F                 596/1199      0/0/0
Core4.03-00           0x0000000F   0x057E                1176/1199      0/0/0
ENR1.00-00            0x00000013   0x1DAC                1158/1199      0/0/0

EDR1.00-00            0x00000012   0x9EF7                 581/1198      0/0/0
EDR1.01-00            0x0000000F   0xE747                1001/1198      0/0/0
EDR1.02-00            0x0000000F   0xF933                 569/1198      0/0/0
EDR2.00-00            0x00000012   0x5861                 639/1198      0/0/0
EDR2.02-00            0x0000000E   0x022A                 774/1198      0/0/0
Core1# 

* The output of this command briefly shows you the entries of the LSP database for entire IS-IS topology, each line represents some part of the database obtained from different nodes participating in the routing process. Two sets of databases exist on this router, one for "Level-1" and another of "level-2" because the Core1's IS-type is L1/L2. IS-Type will be discussed in future labs. Asterisks right after the top three lines for Core1 indicate that the origin of these entries Core1 router itself. More information about the IS-IS Link-state database will be described in the next lab.


Core1#show ip route isis
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 16 subnets, 2 masks
i L1     10.0.0.12/30 [115/20] via 10.0.0.10, 03:23:19, GigabitEthernet0/3
                      [115/20] via 10.0.0.6, 03:23:19, GigabitEthernet0/2
i L1     10.0.0.16/30 [115/20] via 10.0.0.6, 03:23:32, GigabitEthernet0/2
                      [115/20] via 10.0.0.2, 03:23:32, GigabitEthernet0/1
i L1     10.0.0.20/30 [115/20] via 10.0.0.10, 03:23:19, GigabitEthernet0/3
                      [115/20] via 10.0.0.2, 03:23:19, GigabitEthernet0/1
i L1     10.0.2.0/30 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
                     [115/20] via 10.0.0.6, 03:23:09, GigabitEthernet0/2
i L1     10.0.3.0/30 [115/20] via 10.0.0.2, 03:23:32, GigabitEthernet0/1
i L1     10.0.3.4/30 [115/20] via 10.0.0.2, 03:23:32, GigabitEthernet0/1
i L1     10.0.4.0/30 [115/20] via 10.0.0.10, 03:23:19, GigabitEthernet0/3
i L1     10.0.4.4/30 [115/20] via 10.0.0.10, 03:23:19, GigabitEthernet0/3
      172.16.0.0/32 is subnetted, 7 subnets
i L1     172.16.100.2 [115/20] via 10.0.0.6, 03:23:32, GigabitEthernet0/2
i L1     172.16.100.3 [115/20] via 10.0.0.2, 03:23:32, GigabitEthernet0/1
i L1     172.16.100.4 [115/20] via 10.0.0.10, 03:23:19, GigabitEthernet0/3

 i L1     172.16.100.11 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.16.100.21 [115/30] via 10.0.0.10, 03:23:09, GigabitEthernet0/3
                       [115/30] via 10.0.0.2, 03:23:09, GigabitEthernet0/1
i L1     172.16.100.22 [115/30] via 10.0.0.10, 03:23:19, GigabitEthernet0/3
                       [115/30] via 10.0.0.2, 03:23:19, GigabitEthernet0/1
      172.17.0.0/24 is subnetted, 8 subnets
i L1     172.17.0.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.17.1.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.17.2.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.17.3.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.17.4.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.17.5.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.17.6.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
i L1     172.17.7.0 [115/20] via 10.0.1.2, 03:23:09, GigabitEthernet0/4
Core1#

* The famous "show ip route" command is one of the most used command, amongst network professionals, here the output shows IS-IS routes have been learned from other nodes, small "i" indicates that IS-IS is responsible for the entries in the routing table, L1 shows that routes are coming from Level1 IS-IS topology and belong to the local Area.


Core1#show  ip protocols
*** IP Routing is NSF aware ***
Routing Protocol is "isis"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Redistributing: isis
  Address Summarization:
    None
  Maximum path: 4
  Routing for Networks:
    Loopback0
    GigabitEthernet0/1
    GigabitEthernet0/2
    GigabitEthernet0/3
    GigabitEthernet0/4
  Routing Information Sources:
    Gateway         Distance      Last Update
 172.16.100.21        115      00:07:38
    172.16.100.22        115      00:07:38
    172.16.100.11        115      00:07:38
    172.16.100.2         115      00:07:38
    172.16.100.3         115      00:07:38
    172.16.100.4         115      00:07:38
  Distance: (default is 115)

* Surprisingly this show command works for IS-IS as well, here addition information can be obtained, for example, if route filtering in place or address summarization enabled.


Core1#show clns interface g0/1
GigabitEthernet0/1 is up, line protocol is up
  Checksums enabled, MTU 1497, Encapsulation SAP
  ERPDUs enabled, min. interval 10 msec.
  CLNS fast switching disabled
  CLNS SSE switching disabled
  DEC compatibility mode OFF for this interface
  Next ESH/ISH in 39 seconds
  Routing Protocol: IS-IS
    Circuit Type: level-1-2
    Interface number 0x1, local circuit ID 0x1
    Level-1 Metric: 10, Priority: 64, Circuit ID: Core1.01
    DR ID: Core1.01
    Level-1 IPv6 Metric: 10
    Number of active level-1 adjacencies: 1
    Level-2 Metric: 10, Priority: 64, Circuit ID: Core1.01
    DR ID: Core1.01
    Level-2 IPv6 Metric: 10
  Number of active level-2 adjacencies: 1
    Next IS-IS LAN Level-1 Hello in 1 seconds
    Next IS-IS LAN Level-2 Hello in 173 milliseconds

* This command reveals similar information as OSPF's "show ip ospf interface g0/1" You can observe the output regarding the hello timers, priority of interface, Circuit Type and ID, Metric configuration, number of active adjacencies, and even who the Designated router is.


Core1#show  clns traffic
CLNS:  Time since last clear: never
CLNS & ESIS Output: 270, Input: 33778
Dropped Protocol not enabled on interface: 0
CLNS Local: 0, Forward: 0
CLNS Discards:
  Hdr Syntax: 0, Checksum: 0, Lifetime: 0, Output cngstn: 0
  No Route: 0, Discard Route: 0, Dst Unreachable 0, Encaps. Failed: 0
  NLP Unknown: 0, Not an IS: 0
CLNS Options: Packets 0, total 0 , bad 0, GQOS 0, cngstn exprncd 0
CLNS Segments:  Segmented: 0, Failed: 0
CLNS Broadcasts: sent: 0, rcvd: 0
Echos: Rcvd 0 requests, 0 replies
      Sent 0 requests, 0 replies
ESIS(sent/rcvd): ESHs: 0/0, ISHs: 270/0, RDs: 0/0, QCF: 0/0
Tunneling (sent/rcvd): IP: 0/0, IPv6: 0/0
Tunneling dropped (rcvd) IP/IPV6:  0
ISO-IGRP: Querys (sent/rcvd): 0/0 Updates (sent/rcvd): 0/0
ISO-IGRP: Router Hellos: (sent/rcvd): 0/0
ISO-IGRP Syntax Errors: 0

IS-IS: Time since last clear: never
IS-IS: Level-1 Hellos (sent/rcvd): 12907/12909
IS-IS: Level-2 Hellos (sent/rcvd): 12905/12920
IS-IS: PTP Hellos     (sent/rcvd): 0/0
IS-IS: Level-1 LSPs sourced (new/refresh): 7/52
IS-IS: Level-2 LSPs sourced (new/refresh): 10/53
IS-IS: Level-1 LSPs flooded (sent/rcvd): 802/720
IS-IS: Level-2 LSPs flooded (sent/rcvd): 816/784
IS-IS: LSP Retransmissions: 0
IS-IS: Level-1 CSNPs (sent/rcvd): 3223/3222
IS-IS: Level-2 CSNPs (sent/rcvd): 3221/3219
IS-IS: Level-1 PSNPs (sent/rcvd): 0/2
IS-IS: Level-2 PSNPs (sent/rcvd): 0/2
IS-IS: Level-1 DR Elections: 10
IS-IS: Level-2 DR Elections: 10
IS-IS: Level-1 SPF Calculations: 19
IS-IS: Level-2 SPF Calculations: 20
IS-IS: Level-1 Partial Route Calculations: 0
IS-IS: Level-2 Partial Route Calculations: 12
IS-IS: LSP checksum errors received: 0
IS-IS: Update process queue depth: 0/200
IS-IS: Update process packets dropped: 0
Core1#

* This command gives you statistics about IS-IS counters for Hello messages, LSPs, CSNPs and PSNPs updates, how many DR Elections occurred, and SPF calculations.


There are also some CLNS commands you can use the same way as "show isis", for example:
Core1#show  clns neighbors 
Core1#show  clns protocol  
Core1#show  clns is-neighbors 


Topology:












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