No tunnels configured, but frequent log messages, "%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel1, changed state to up"

[russemerson]

ASR 1002 running 12.2(33)XND3.  We're seeing the %LINEPROTO-5-UPDOWN log message every 5 to 15 minutes, always "changed state to up" despite there never having been any tunnel interface configured on the box.

Additionally, we do get output from the "show interface tunnel1" command:

CADBEWEFMP650#sh int tu1
Tunnel1 is up, line protocol is up
  Hardware is Tunnel
  Interface is unnumbered. Using address of GigabitEthernet0/0/0.1 (10.137.3.178)
  MTU 17872 bytes, BW 100 Kbit, DLY 50000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 10.137.3.178 (GigabitEthernet0/0/0.1), destination 146.194.1.131
  Tunnel protocol/transport PIM/IPv4, key
  Tunnel TOS/Traffic Class 0xC0,  Tunnel TTL 255
  Tunnel transport MTU 1480 bytes
  Tunnel transmit bandwidth 8000 (kbps)
  Tunnel receive bandwidth 8000 (kbps)
  Last input never, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/0 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     0 packets output, 0 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 output buffer failures, 0 output buffers swapped out
CADBEWEFMP650#

Clearly, I'm missing something here.  Could this perhaps be some sort of tunnel that is dynamically created, without requiring actual configuration?

[Seb Rupik · Accepted solution]

Hi there,

This is normal behaviour when you have 'ipv6 multicast-routing' (PIM-SM) in your configuration.

With IPv6, this tunnel is used for the PIM register process.

cheers,

Seb.

[Sivasubramanian Sundaram]

Hi,

I see the same issue, but i have ip multicast-routing (ipv4) configured.

%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up

Seeing the above message continuously. Is this can be ignored as the PIM register process?

[Seb Rupik]

Hi there,

These tunnels are created by the Multicast forwarding Information Base during the PIM sparse-mode registration process, irrespective of IP protocol.

Take a look here:

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_mfib/configuration/xe-3s/imc-mfib-xe-3s-book/imc_verify_mfib.html#GUID-C599FACD-6348-451D-831B-5941F26C5760

cheers,

Seb.

[Sivasubramanian Sundaram]

Thanks a lot Seb.