what is the feature of IOS on ISRg2 that automatic create tunnel0 when "show ip int brief"

[tana_kongkriengkrai]

I got question from my customer that he configure ISRg2, when he try "show ip int brief", he see that router has tunnel0 and use same IP address as Gi0.

#sh ip int brief

Interface                  IP-Address      OK? Method Status                Protocol

GigabitEthernet0/0         10.88.2.1       YES NVRAM  up                    up     

GigabitEthernet0/1         10.188.2.1      YES NVRAM  up                    up     

Serial0/0/0                172.29.88.88    YES NVRAM  up                    up     

Serial0/0/1                unassigned      YES NVRAM  administratively down down   

Tunnel0                    10.88.2.1       YES unset  up                    up    

He send "show run" that haven't any config about tunnel0. I would like to know what is tunnel0 for? And does it effect to any operate of router or not.

sh ver

Cisco IOS Software, C2900 Software (C2900-UNIVERSALK9-M), Version 15.1(2)T2, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2010 by Cisco Systems, Inc.

Compiled Sat 23-Oct-10 01:25 by prod_rel_team

ROM: System Bootstrap, Version 15.0(1r)M9, RELEASE SOFTWARE (fc1)

uptime is 19 hours, 52 minutes

System returned to ROM by power-on

System restarted at 20:37:22 GMT+7 Wed Jan 5 2011

System image file is "flash0:c2900-universalk9-mz.SPA.151-2.T2.bin"

Last reload type: Normal Reload

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

Cisco CISCO2901/K9 (revision 1.0) with 475136K/49152K bytes of memory.

Processor board ID FHK1446737G

2 Gigabit Ethernet interfaces

2 Serial(sync/async) interfaces

1 Virtual Private Network (VPN) Module

DRAM configuration is 64 bits wide with parity enabled.

255K bytes of non-volatile configuration memory.

254464K bytes of ATA System CompactFlash 0 (Read/Write)

License Info:

License UDI:

-------------------------------------------------

Device#   PID                   SN

-------------------------------------------------

*0        CISCO2901/K9              

Technology Package License Information for Module:'c2900'

----------------------------------------------------------------

Technology    Technology-package          Technology-package

              Current       Type          Next reboot 

-----------------------------------------------------------------

ipbase        ipbasek9      Permanent     ipbasek9

security      securityk9    Permanent     securityk9

uc            None          None          None

data          datak9        Permanent     datak9

Configuration register is 0x2102

[Yasir Ashfaque]

It depends, why dont you share the show running

[tana_kongkriengkrai]

This is "show run" from my customer. I remove some line about description, username and serial number

Current configuration : 5882 bytes

!

! Last configuration change at 16:11:42 GMT+7 Thu Jan 6 2011 by jiruttaphol

! NVRAM config last updated at 21:45:39 GMT+7 Wed Jan 5 2011 by jiruttaphol

!

version 15.1

service timestamps debug datetime msec localtime

service timestamps log datetime msec localtime

service password-encryption

!

hostname ABC!

boot-start-marker

boot-end-marker

!

!

logging buffered 40960

no logging monitor

!

no aaa new-model

!

memory-size iomem 10

clock timezone GMT+7 7 0

!

no ipv6 cef

ip source-route

ip cef

!

!

!

ip multicast-routing

!

!

no ip domain lookup

!

multilink bundle-name authenticated

!

decnet routing 12.288

decnet node-type routing-iv

!

!

!

crypto pki token default removal timeout 0

!

crypto pki trustpoint TP-self-signed-3985897665

enrollment selfsigned

subject-name cn=IOS-Self-Signed-Certificate-3985897665

revocation-check none

!

!

crypto pki certificate chain TP-self-signed-3985897665

certificate self-signed 01

  3082023F 308201A8 A0030201 02020101 300D0609 2A864886 F70D0101 04050030

  31312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274

  69666963 6174652D 33393835 38393736 3635301E 170D3131 30313035 31333338

  35315A17 0D323030 31303130 30303030 305A3031 312F302D 06035504 03132649

  4F532D53 656C662D 5369676E 65642D43 65727469 66696361 74652D33 39383538

  39373636 3530819F 300D0609 2A864886 F70D0101 01050003 818D0030 81890281

  81009A92 0FE6D97D 89B87C67 49EBE78A 1A752AF1 3E40A514 2086D6CF A571CC2A

  4A4E21FD 4FDC495F 9F252B9B D8AD98EB 612E3A49 24C4E2CE 350AFD4C 07A95B17

  54F192FE 261F372D 8A64B630 B1BD9E87 44C14497 72C43526 46803778 1581745E

  1AEEC453 AD5C74C5 CCF8E64C C44F081D B7ACD1EE 0D37B441 AC0F480A 2DDEEDD5

  645B0203 010001A3 67306530 0F060355 1D130101 FF040530 030101FF 30120603

  551D1104 0B300982 07445055 5F525431 301F0603 551D2304 18301680 14C97B60

  41D4C892 9604D5BD FC7C4D21 D3C6D45A F1301D06 03551D0E 04160414 C97B6041

  D4C89296 04D5BDFC 7C4D21D3 C6D45AF1 300D0609 2A864886 F70D0101 04050003

  81810018 8DA44803 DC0BD861 28EE66AF 3CBFD661 F027AE06 63F318FC 42363BFD

  DEDB8418 207CCD38 2CE07E12 A2ABBF3B 4031B80E 4B6AA922 21DC4501 6CB9806F

  26E89356 96972CB5 7005119B E4D90418 0C50F421 2FB5CC63 4BE71555 35CB8F3C

  C774BCEE BDE71E43 2D918AA4 54B0D706 4223C004 4BCC6D22 ECDFB5AE 4C0F5994 090194

        quit

license udi pid CISCO2901/K9 sn xxxx

!

!

redundancy

!

!

!

!

!

track 1 interface Serial0/0/0 line-protocol

!

!

!

!

!

!

!       

interface GigabitEthernet0/0

ip address 10.88.2.1 255.255.0.0

no ip redirects

ip pim sparse-dense-mode

ip ospf cost 80

load-interval 30

duplex auto

speed auto

standby use-bia

standby 0 ip 10.88.2.254

standby 0 preempt

standby 0 track 1 decrement 10

!

interface GigabitEthernet0/1

ip address 10.188.2.1 255.255.0.0

no ip redirects

ip pim sparse-dense-mode

ip ospf cost 180

duplex auto

speed auto

standby 2 ip 10.188.2.254

standby 2 priority 95

standby 2 preempt

standby 2 track 1 decrement 10

!

interface Serial0/0/0

bandwidth 128

ip address 172.29.88.88 255.255.255.0

ip accounting output-packets

ip pim sparse-dense-mode

ip ospf cost 310

load-interval 30

decnet cost 10

priority-group 10

keepalive 5

!

interface Serial0/0/1

no ip address

shutdown

clock rate 2000000

!

!

router ospf 100

network 10.88.0.0 0.0.255.255 area 88

network 10.188.0.0 0.0.255.255 area 88

network 172.29.88.0 0.0.0.255 area 88

!

no ip forward-protocol nd

!

no ip http server

ip http authentication local

ip http secure-server

ip http timeout-policy idle 5 life 86400 requests 10000

!

ip route 172.17.0.0 255.255.0.0 172.29.188.20

ip route 172.17.0.0 255.255.0.0 172.29.88.1 20

ip route 172.19.0.0 255.255.255.0 172.29.88.20

ip route 172.19.0.0 255.255.255.0 172.29.88.1 20

ip route 192.168.223.0 255.255.255.0 172.29.88.20

ip route 192.168.223.0 255.255.255.0 172.29.88.1 20

ip route 192.168.224.0 255.255.255.0 172.29.188.20

ip route 192.168.224.0 255.255.255.0 172.29.88.1 20

ip route 192.168.225.0 255.255.255.0 172.29.188.20

ip route 192.168.225.0 255.255.255.0 172.29.88.1 20

!

logging esm config

logging 172.16.10.166

priority-list 10 protocol decnet high

priority-list 10 protocol ip high list 191

priority-list 10 protocol ip medium list 192

priority-list 10 protocol ip normal list 193

priority-list 10 protocol ip medium

priority-list 10 default low

!

!

!

!

!       

!

snmp-server engineID local 800000092300000B5F430460

snmp-server community XX RO

snmp-server enable traps tty

!

control-plane

!

!

line con 0

logging synchronous

login local

line aux 0

logging synchronous

modem InOut

no exec

transport preferred telnet

transport input all

escape-character NONE

stopbits 1

speed 19200

line vty 0 4

exec-timeout 0 0

privilege level 15

logging synchronous

login local

transport input telnet ssh

line vty 5 15

privilege level 15

logging synchronous

login local

transport input telnet ssh

!

scheduler allocate 20000 1000

ntp server 172.16.10.166 prefer

end

[Mahesh Gohil]

Hello,

I am not sure but this happens when you enable pim multicast. Can you confirm the output of "sh ip pim neighbor" contain this

tunnel0 as an interface

Regards

Mahesh

[Yasir Ashfaque]

its because IP Multicast Sparse Mode

[Yasir Ashfaque]

You can verify it from show int tunnel0

it will show it as  Tunnel protocol/transport PIM/IPv4.

[tana_kongkriengkrai]

Thank you for your answer, I will check with my customer.