[c-nsp] Mysterious tunnel interfaces

Jay Nakamura zeusdadog at gmail.com
Thu Aug 12 13:34:52 EDT 2010


Mystery deepens.

Router#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#int tun0
% This interface cannot be modified
Router(config)#no int tun0
% This interface cannot be modified
Router(config)#int tun2
% This interface cannot be modified
Router(config)#int tun3
% This interface cannot be modified
Router(config)#^Z
Router#sh ip pim tunnel

Router#

Nothing in "show run all" for these interfaces.

I don't have multicast configured, or at least I haven't actively
configured anything for it.  I haven't really had to do anything with
Multicast so I am not familiar with it.

I do have IOS content filtering installed/configured but I don't think
that will do this.

I do have ZBFW configured.

I do not have VRF on this router.

Here are some outputs of the interfaces

Router#sh int tunn0
Tunnel0 is up, line protocol is up
  Hardware is Tunnel
  Interface is unnumbered. Using address of Tunnel2 (172.16.0.1)
  MTU 17912 bytes, BW 100 Kbit/sec, DLY 50000 usec,
     reliability 255/255, txload 81/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 172.19.128.31
  Tunnel protocol/transport multi-GRE/IP
    Key disabled, sequencing disabled
    Checksumming of packets disabled
  Tunnel TTL 255, Fast tunneling enabled
  Tunnel transport MTU 1472 bytes
  Tunnel transmit bandwidth 8000 (kbps)
  Tunnel receive bandwidth 8000 (kbps)
  Last input never, output 17:22:42, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (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 32000 bits/sec, 2 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     95997 packets output, 26708838 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 unknown protocol drops
     0 output buffer failures, 0 output buffers swapped out
Router#sh int tunn2
Tunnel2 is up, line protocol is up
  Hardware is Tunnel
  Internet address is 172.16.0.1/16
  MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 172.16.0.1
  Tunnel protocol/transport multi-GRE/IP
    Key disabled, sequencing disabled
    Checksumming of packets disabled
  Tunnel TTL 255, Fast tunneling enabled
  Tunnel transport MTU 1476 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: 0/75/0/0 (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 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 unknown protocol drops
     0 output buffer failures, 0 output buffers swapped out
Router#sh int tunn3
Tunnel3 is up, line protocol is up
  Hardware is Tunnel
  Interface is unnumbered. Using address of Tunnel2 (172.16.0.1)
  MTU 17912 bytes, BW 100 Kbit/sec, DLY 50000 usec,
     reliability 255/255, txload 7/255, rxload 1/255
  Encapsulation TUNNEL, loopback not set
  Keepalive not set
  Tunnel source 172.19.128.31
  Tunnel protocol/transport multi-GRE/IP
    Key disabled, sequencing disabled
    Checksumming of packets disabled
  Tunnel TTL 255, Fast tunneling enabled
  Tunnel transport MTU 1472 bytes
  Tunnel transmit bandwidth 8000 (kbps)
  Tunnel receive bandwidth 8000 (kbps)
  Last input never, output 05:17:13, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (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 3000 bits/sec, 2 packets/sec
     0 packets input, 0 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     111685 packets output, 18723536 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 unknown protocol drops
     0 output buffer failures, 0 output buffers swapped out
Router#sh ip int tun0
Tunnel0 is up, line protocol is up
  Interface is unnumbered. Using address of Tunnel2 (172.16.0.1)
  Broadcast address is 255.255.255.255
  MTU is 17856 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are never sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is disabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF switching turbo vector
  IP Null turbo vector
  VPN Routing/Forwarding "tunnel-group-ivrf"
  Downstream VPN Routing/Forwarding ""
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF
  Router Discovery is disabled
  IP output packet accounting is disabled
  IP access violation accounting is disabled
  TCP/IP header compression is disabled
  RTP/IP header compression is disabled
  Policy routing is disabled
  Network address translation is disabled
  BGP Policy Mapping is disabled
  Input features: MCI Check
  Output features: CCE Post NAT Classification, Firewall (firewall component)
  WCCP Redirect outbound is disabled
  WCCP Redirect inbound is disabled
  WCCP Redirect exclude is disabled
Router#sh ip int tun2
Tunnel2 is up, line protocol is up
  Internet address is 172.16.0.1/16
  Broadcast address is 255.255.255.255
  Address determined by unknown means
  MTU is 1476 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are never sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is disabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF switching turbo vector
  IP Null turbo vector
  VPN Routing/Forwarding "tunnel-group-ivrf"
  Downstream VPN Routing/Forwarding ""
  Tunnel VPN Routing/Forwarding "tunnel-group-ivrf"
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF
  Router Discovery is disabled
  IP output packet accounting is disabled
  IP access violation accounting is disabled
  TCP/IP header compression is disabled
  RTP/IP header compression is disabled
  Policy routing is disabled
  Network address translation is disabled
  BGP Policy Mapping is disabled
  Input features: MCI Check
  Output features: CCE Post NAT Classification, Firewall (firewall component)
  WCCP Redirect outbound is disabled
  WCCP Redirect inbound is disabled
  WCCP Redirect exclude is disabled
Router#sh ip int tun3
Tunnel3 is up, line protocol is up
  Interface is unnumbered. Using address of Tunnel2 (172.16.0.1)
  Broadcast address is 255.255.255.255
  MTU is 17856 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are never sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is disabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF switching turbo vector
  IP Null turbo vector
  VPN Routing/Forwarding "tunnel-group-ivrf"
  Downstream VPN Routing/Forwarding ""
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF
  Router Discovery is disabled
  IP output packet accounting is disabled
  IP access violation accounting is disabled
  TCP/IP header compression is disabled
  RTP/IP header compression is disabled
  Policy routing is disabled
  Network address translation is disabled
  BGP Policy Mapping is disabled
  Input features: MCI Check
  Output features: CCE Post NAT Classification, Firewall (firewall component)
  WCCP Redirect outbound is disabled
  WCCP Redirect inbound is disabled
  WCCP Redirect exclude is disabled




On Thu, Aug 12, 2010 at 9:39 AM, Luan Nguyen <luan at netcraftsmen.net> wrote:
> I have those ISR2 (M1) as well as ASR1002 running DMVPN and don't have those
> ghost tunnels.  Must be for some other services such as multicast.
> Try to remove them with no interface tunnel 0, and I think the router will
> tell you why you couldn't.
>
> Regards,
>
> -Luan
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Jay Nakamura
> Sent: Wednesday, August 11, 2010 8:53 PM
> To: cisco-nsp
> Subject: [c-nsp] Mysterious tunnel interfaces
>
> I was working on a ISR 1941 with 15.0(1)M2.  I am running DMVPN on it
> and using one tunnel interface.  (Tunnel 1).  No other tunnel
> interfaces are configured on the router.  However when I do "show int
> summary" I get this;
>
> #sh int summary
>
>  *: interface is up
>  IHQ: pkts in input hold queue     IQD: pkts dropped from input queue
>  OHQ: pkts in output hold queue    OQD: pkts dropped from output queue
>  RXBS: rx rate (bits/sec)          RXPS: rx rate (pkts/sec)
>  TXBS: tx rate (bits/sec)          TXPS: tx rate (pkts/sec)
>  TRTL: throttle count
>
>  Interface              IHQ   IQD  OHQ   OQD  RXBS RXPS  TXBS TXPS TRTL
> ------------------------------------------------------------------------
> * GigabitEthernet0/0       0     0    0     0  6000    5  6000    5    0
>  GigabitEthernet0/1       0     0    0     0     0    0     0    0    0
> * Serial0/0/0              0     0    0     0  3000    3  2000    2    0
>  NVI0                     0     0    0     0     0    0     0    0    0
> * Tunnel0                  0     0    0     0     0    0     0    0    0
> * Tunnel1                  0     0    0    10  1000    2  1000    2    0
> * Tunnel2                  0     0    0     0     0    0     0    0    0
> * Tunnel3                  0     0    0     0     0    0     0    0    0
>
> I thought may be something got left behind while I was monkeying
> around in it so I reloaded the router and the tunnel 0,2,3 are still
> there and it says it's up.   None of those interfaces are in the
> startup or running-config.
>
> What is going on here?  My other routers with similar config on a 1841
> with 12.4(15)T* doesn't have this issue.  It doesn't seem to be
> affecting the routing of traffic but it's really bothering me.
>
> -Jay
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