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Check Link Hook

This example demonstrates how to process outgoing NHRP traffic in a scenario using one Tunnel with GRE encapsulation.

../../../../../_images/topology19.svg

Test Marks In NHRP Traffic

Description

In this scenario, a traffic policy was configured to log outgoing NHRP traffic, which is non-IP Layer 3 protocol. The special hook link-out can be used to process these outgoing frames.

Scenario

Step 1: Set the following configuration in DUT0 :

set interfaces ethernet eth0 address 192.168.100.10/24
set interfaces tunnel tun0 address 10.0.0.1/32
set interfaces tunnel tun0 encapsulation gre
set interfaces tunnel tun0 local-address 192.168.100.10
set interfaces tunnel tun0 nhrp
set interfaces tunnel tun0 traffic policy link-in LOG_NHRP
set interfaces tunnel tun0 traffic policy link-out LOG_NHRP
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'
set traffic policy LOG_NHRP rule 1 log prefix NHRP__
set traffic policy LOG_NHRP rule 1 selector NHRP_SEL
set traffic selector NHRP_SEL rule 1 ether-type 8193

Note

NHRP packets use ethertype 8193 (0x2001).

Step 2: Set the following configuration in DUT1 :

set interfaces ethernet eth0 address 192.168.100.20/24
set interfaces tunnel tun0 address 10.0.0.2/32
set interfaces tunnel tun0 encapsulation gre
set interfaces tunnel tun0 local-address 192.168.100.20
set interfaces tunnel tun0 nhrp holdtime 5
set interfaces tunnel tun0 nhrp nhs 10.0.0.1 nbma 192.168.100.10
set system login user admin authentication encrypted-password '$6$GSjsCj8gHLv$/VcqU6FLi6CT2Oxn0MJQ2C2tqnRDrYKNF8HIYWJp68nvXvPdFccDsT04.WtigUONbKYrgKg8d6rEs8PjljMkH0'

Step 3: Run command protocols ip show nhrp at DUT0 and check if output matches the following regular expressions:

tun0\s+dynamic\s+10\.0\.0\.2
Show output
Iface      Type     Protocol         NBMA             Claimed NBMA     Expires(s)   Flags  Identity
tun0       local    10.0.0.1         192.168.100.10   192.168.100.10   -                   -
tun0       dynamic  10.0.0.2         192.168.100.20   192.168.100.20   5            UT

Step 4: Run command system journal show | cat at DUT0 and check if output matches the following regular expressions:

\[NHRP__-1\] ACCEPT IN=tun0 OUT=\w+
\[NHRP__-1\] ACCEPT IN= OUT=tun0
Show output
Mar 05 18:09:13.000210 osdx systemd-timedated[546780]: Changed local time to Thu 2026-03-05 18:09:13 UTC
Mar 05 18:09:13.001681 osdx OSDxCLI[559085]: User 'admin' executed a new command: 'set date 2026-03-05 18:09:13'.
Mar 05 18:09:13.002552 osdx systemd-journald[466780]: Time jumped backwards, rotating.
Mar 05 18:09:13.412383 osdx systemd-journald[466780]: Runtime Journal (/run/log/journal/78445f9299f9414990e66dc8aa510838) is 1.8M, max 13.8M, 12.0M free.
Mar 05 18:09:13.414560 osdx systemd-journald[466780]: Received client request to rotate journal, rotating.
Mar 05 18:09:13.414628 osdx systemd-journald[466780]: Vacuuming done, freed 0B of archived journals from /run/log/journal/78445f9299f9414990e66dc8aa510838.
Mar 05 18:09:13.422387 osdx OSDxCLI[559085]: User 'admin' executed a new command: 'system journal clear'.
Mar 05 18:09:13.620677 osdx OSDxCLI[559085]: User 'admin' executed a new command: 'system coredump delete all'.
Mar 05 18:09:13.831703 osdx OSDxCLI[559085]: User 'admin' entered the configuration menu.
Mar 05 18:09:13.915081 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set interfaces ethernet eth0 address 192.168.100.10/24'.
Mar 05 18:09:13.986646 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 traffic policy link-out LOG_NHRP'.
Mar 05 18:09:14.072099 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 traffic policy link-in LOG_NHRP'.
Mar 05 18:09:14.124062 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 address 10.0.0.1/32'.
Mar 05 18:09:14.217963 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 encapsulation gre'.
Mar 05 18:09:14.271271 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 local-address 192.168.100.10'.
Mar 05 18:09:14.375526 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set interfaces tunnel tun0 nhrp'.
Mar 05 18:09:14.472208 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set traffic policy LOG_NHRP rule 1 log prefix NHRP__'.
Mar 05 18:09:14.525088 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set traffic policy LOG_NHRP rule 1 selector NHRP_SEL'.
Mar 05 18:09:14.622689 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'set traffic selector NHRP_SEL rule 1 ether-type 8193'.
Mar 05 18:09:14.684108 osdx OSDxCLI[559085]: User 'admin' added a new cfg line: 'show working'.
Mar 05 18:09:14.802657 osdx ubnt-cfgd[560591]: inactive
Mar 05 18:09:14.886854 osdx systemd[1]: Reloading frr.service - FRRouting...
Mar 05 18:09:14.899576 osdx watchfrr[551677]: [NG1AJ-FP2TQ] Terminating on signal
Mar 05 18:09:15.000512 osdx frrinit.sh[560621]: Stopped watchfrr.
Mar 05 18:09:15.001424 osdx frrinit.sh[560621]: Starting watchfrr with command: '  /usr/lib/frr/watchfrr  -d  --min-restart-interval 1 --max-restart-interval 600 --timeout 600 --restart-timeout 600 zebra mgmtd nhrpd staticd'.
Mar 05 18:09:15.007688 osdx watchfrr[560639]: [T83RR-8SM5G] watchfrr 10.4.1 starting: vty@0
Mar 05 18:09:15.007726 osdx watchfrr[560639]: [QDG3Y-BY5TN] zebra state -> up : connect succeeded
Mar 05 18:09:15.007744 osdx watchfrr[560639]: [QDG3Y-BY5TN] mgmtd state -> up : connect succeeded
Mar 05 18:09:15.007766 osdx watchfrr[560639]: [ZCJ3S-SPH5S] nhrpd state -> down : initial connection attempt failed
Mar 05 18:09:15.007768 osdx watchfrr[560639]: [QDG3Y-BY5TN] staticd state -> up : connect succeeded
Mar 05 18:09:15.007901 osdx watchfrr[560639]: [YFT0P-5Q5YX] Forked background command [pid 560640]: /usr/lib/frr/watchfrr.sh restart nhrpd
Mar 05 18:09:15.011509 osdx frrinit.sh[560640]: Cannot stop nhrpd: pid file not found
Mar 05 18:09:15.012390 osdx watchfrr.sh[560645]: Cannot stop nhrpd: pid file not found
Mar 05 18:09:15.022100 osdx zebra[160016]: [V98V0-MTWPF] client 36 says hello and bids fair to announce only nhrp routes vrf=0
Mar 05 18:09:15.031199 osdx watchfrr[560639]: [QDG3Y-BY5TN] nhrpd state -> up : connect succeeded
Mar 05 18:09:15.031209 osdx watchfrr[560639]: [KWE5Q-QNGFC] all daemons up, doing startup-complete notify
Mar 05 18:09:15.031411 osdx frrinit.sh[560650]: sh: line 1: ipsec: command not found
Mar 05 18:09:15.031841 osdx frrinit.sh[560621]: Started watchfrr.
Mar 05 18:09:15.124416 osdx systemd[1]: Reloaded frr.service - FRRouting.
Mar 05 18:09:15.154552 osdx kernel: 8021q: adding VLAN 0 to HW filter on device eth0
Mar 05 18:09:15.200326 osdx WARNING[560743]: No supported link modes on interface eth0
Mar 05 18:09:15.201671 osdx modulelauncher[560743]: osdx.utils.xos cmd error: /sbin/ethtool -A eth0 autoneg on
Mar 05 18:09:15.201683 osdx modulelauncher[560743]: Command '/sbin/ethtool -A eth0 autoneg on' returned non-zero exit status 76.
Mar 05 18:09:15.202836 osdx modulelauncher[560743]: osdx.utils.xos cmd error: /sbin/ethtool -s eth0 autoneg on advertise Pause off Asym_Pause off --
Mar 05 18:09:15.202845 osdx modulelauncher[560743]: Command '/sbin/ethtool -s eth0 autoneg on advertise Pause off Asym_Pause off --' returned non-zero exit status 75.
Mar 05 18:09:15.222571 osdx (udev-worker)[560771]: Network interface NamePolicy= disabled on kernel command line.
Mar 05 18:09:15.446259 osdx cfgd[1863]: [559085]Completed change to active configuration
Mar 05 18:09:15.468994 osdx OSDxCLI[559085]: User 'admin' committed the configuration.
Mar 05 18:09:15.489949 osdx OSDxCLI[559085]: User 'admin' left the configuration menu.
Mar 05 18:09:16.956961 osdx OSDxCLI[559085]: User 'admin' executed a new command: 'protocols ip show nhrp'.
Mar 05 18:09:17.850565 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT= MAC=45:00:00:74:78:48:40:00:40:2f:78:a3:c0:a8:64:14:c0:a8:64:0a:00:00:20:01
Mar 05 18:09:17.850639 osdx kernel: [NHRP__-1] ACCEPT IN= OUT=tun0 MAC=45:01:00:00:00:00:40:00:40:2f:00:00:c0:a8:64:0a:c0:a8:64:14:00:00:20:01
Mar 05 18:09:17.850648 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT=eth0 MAC=00:01:08:00:00:00:00:00:00:40:00:70:2b:43:00:34:01:04:04:00:04:04:00:02
Mar 05 18:09:18.849025 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT= MAC=45:00:00:74:78:b8:40:00:40:2f:78:33:c0:a8:64:14:c0:a8:64:0a:00:00:20:01
Mar 05 18:09:18.849107 osdx kernel: [NHRP__-1] ACCEPT IN= OUT=tun0 MAC=45:01:00:00:00:00:40:00:40:2f:00:00:c0:a8:64:0a:c0:a8:64:14:00:00:20:01
Mar 05 18:09:18.849117 osdx kernel: [NHRP__-1] ACCEPT IN=tun0 OUT=eth0 MAC=00:01:08:00:00:00:00:00:00:40:00:70:2b:42:00:34:01:04:04:00:04:04:00:02
Mar 05 18:09:19.025732 osdx OSDxCLI[559085]: User 'admin' executed a new command: 'protocols ip show nhrp'.

Step 5: Run command traffic policy show at DUT0 and check if output matches the following regular expressions:

1\s+NHRP_SEL\s+\b[^0]\d*
Show output
Policy LOG_NHRP -- ifc tun0 -- hook link-in prio very-high

---------------------------------------------------------------
rule   selector  pkts match  pkts eval  bytes match  bytes eval
---------------------------------------------------------------
1      NHRP_SEL           4          4          456         456
---------------------------------------------------------------
Total                     4          4          456         456

Policy LOG_NHRP -- ifc tun0 -- hook link-out prio very-high

---------------------------------------------------------------
rule   selector  pkts match  pkts eval  bytes match  bytes eval
---------------------------------------------------------------
1      NHRP_SEL           2          2          272         272
---------------------------------------------------------------
Total                     2          2          272         272
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