Description

RE0 does not process connectivity with management IP configured example FXP0

Symptoms

Unable to ping or SSH connection to FXP0. In this example the IP configured is 10.12.18.98

 

user@router> monitor traffic interface fxp0

verbose output suppressed, use <detail> or <extensive> for full protocol decode

Address resolution is ON. Use <no-resolve> to avoid any reverse lookup delay.

Address resolution timeout is 4s.

Listening on fxp0, capture size 96 bytes

 

Reverse lookup for 172.16.21.40 failed (check DNS reachability).

Other reverse lookup failures will not be reported.

Use <no-resolve> to avoid reverse lookups on IP addresses.

 

04:10:31.168597 In IP 172.16.21.40.52835 > 10.12.18.98.ssh: S 553335962:553335962(0) win 64240 <mss 1368,nop,wscale 8,nop,nop,sackOK>

04:10:31.564816 In IP truncated-ip - 11 bytes missing! 172.22.37.157.51330 > 10.12.18.98.snmp: GetRequest(17) [|snmp]

04:10:31.607760 In IP truncated-ip - 24 bytes missing! 10.12.18.232 > 10.12.18.98: ICMP echo request, id 38539, seq 1264, length 64

04:10:31.611659 In STP 802.1w, Rapid STP, Flags [Learn, Forward], bridge-id 8000.2c:6b:f5:9a:05:81.8217, length 43

04:10:31.655022 In IP truncated-ip - 11 bytes missing! 172.22.37.157.51330 > 10.12.18.98.snmp: GetRequest(17) [|snmp]

04:10:31.744683 In IP truncated-ip - 11 bytes missing! 172.22.37.157.51330 > 10.12.18.98.snmp: GetRequest(17) [|snmp]

04:10:32.608499 In IP truncated-ip - 24 bytes missing! 10.12.18.232 > 10.12.18.98: ICMP echo request, id 38539, seq 1265, length 64

04:10:32.656147 In IP 172.16.21.11.54108 > 10.12.18.98.ssh: S 3761207907:3761207907(0) win 64240 <mss 1460,nop,wscale 8,nop,nop,sackOK>

04:10:33.442630 In STP 802.1w, Rapid STP, Flags [Learn, Forward], bridge-id 8000.2c:6b:f5:9a:05:81.8217, length 43

04:10:33.449511 In IP 172.16.21.121.56127 > 10.12.18.98.ssh: S 1082106749:1082106749(0) win 64240 <mss 1460,nop,wscale 8,nop,nop,sackOK>

04:10:33.609675 In IP truncated-ip - 24 bytes missing! 10.12.18.232 > 10.12.18.98: ICMP echo request, id 38539, seq 1266, length 64

04:10:33.670034 In IP 172.16.21.11.54108 > 10.12.18.98.ssh: S 3761207907:3761207907(0) win 64240 <mss 1460,nop,wscale 8,nop,nop,sackOK>

04:10:33.762479 In IP 172.29.46.116.52203 > 10.12.18.98.ssh: S 1534039720:1534039720(0) win 65229 <mss 1279,nop,wscale 8,nop,nop,sackOK>

04:10:34.463070 In IP 172.16.21.121.56127 > 10.12.18.98.ssh: S 1082106749:1082106749(0) win 64240 <mss 1460,nop,wscale 8,nop,nop,sackOK>

04:10:34.563785 In IP truncated-ip - 12 bytes missing! 172.22.37.157.51330 > 10.12.18.98.snmp: C=private GetRequest(16) [|snmp]

04:10:34.610317 In IP truncated-ip - 24 bytes missing! 10.12.18.232 > 10.12.18.98: ICMP echo request, id 38539, seq 1267, length 64

04:10:34.653613 In IP truncated-ip - 12 bytes missing! 172.22.37.157.51330 > 10.12.18.98.snmp: C=private GetRequest(16) [|snmp]

04:10:34.743230 In IP truncated-ip - 12 bytes missing! 172.22.37.157.51330 > 10.12.18.98.snmp: C=private GetRequest(16) [|snmp]

 

Even FXP0 enable up up

 

user@router> show interfaces fxp0        

Physical interface: fxp0, Enabled, Physical link is Up

 Interface index: 66, SNMP ifIndex: 1

 Type: Ethernet, Link-level type: Ethernet, MTU: 1514, Speed: 1000 Mbps

 Device flags : Present Running

 Interface flags: SNMP-Traps

 Link type   : Full-Duplex

 Current address: 04:69:8f:9f:1c:6a, Hardware address: 04:69:8f:9f:1c:6a

 Last flapped : 2024-07-01 07:22:03 CST (00:00:14 ago)

  Input packets : 267402812

  Output packets: 371379830

 

 Logical interface fxp0.0 (Index 7) (SNMP ifIndex 13)

  Flags: Up SNMP-Traps Encapsulation: ENET2

  Input packets : 267402652

  Output packets: 371379830

  Protocol inet, MTU: 1500

  Max nh cache: 75000, New hold nh limit: 75000, Curr nh cnt: 2, Curr new hold cnt: 0, NH drop cnt: 0

   Flags: Sendbcast-pkt-to-re, Is-Primary

   Addresses, Flags: Is-Preferred Is-Primary

    Destination: 10.12.18.96/29, Local: 10.12.18.98, Broadcast: 10.12.18.103

Solution

1-Verify the next hop connection

2- If FF is blocking the connection

3- Swap the IP configured, then re-stablish the previous IP address, and check connectivity

In some cases, this configuration IP address swap could help to enable connection again.

 

 

Modification History

2024-07-10 : Article Created