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Physical Interface not present in show ip route connected

Hi,

Thanks for reading my post.

I have a reccurent issue with a CISCO881-K9.

My WAN interface is regularly unsuable even if it's UP/UP. I can't even ping the interface from the router itself.

A reboot solves the issue. But now I have time and I'd like to get a proper understanding of what's going on.

The route doesn't appear in "show ip route connected".

Router#show ip interface brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0              unassigned      YES unset  up                    up
FastEthernet1              unassigned      YES unset  down                  down
FastEthernet2              unassigned      YES unset  down                  down
FastEthernet3              unassigned      YES unset  down                  down
FastEthernet4              X.Y.Z.82    YES NVRAM  up                    up
Loopback0                  10.31.129.5     YES NVRAM  up                    up
NVI0                       X.Y.Z.82    YES unset  up                    up
Tunnel0                    10.32.129.1     YES NVRAM  up                    down
Vlan1                      172.22.129.102  YES NVRAM  up                    up

Router#ping X.Y.Z.82
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to X.Y.Z.82, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Router#

Router#show ip route

 

Gateway of last resort is X.Y.Z.81 to network 0.0.0.0

 

S*    0.0.0.0/0 [1/0] via X.Y.Z.81
      10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
R        10.30.129.0/24 [120/1] via 172.22.129.101, 00:00:08, Vlan1
R        10.31.129.1/32 [120/1] via 172.22.129.101, 00:00:08, Vlan1
C        10.31.129.5/32 is directly connected, Loopback0
      172.22.0.0/16 is variably subnetted, 3 subnets, 2 masks
S        172.22.128.0/24 [1/0] via 172.28.28.254
C        172.22.129.0/24 is directly connected, Vlan1
L        172.22.129.102/32 is directly connected, Vlan1
      172.27.0.0/24 is subnetted, 1 subnets
S        172.27.0.0 [1/0] via 172.28.28.254
      172.28.0.0/24 is subnetted, 1 subnets
R        172.28.28.0 [120/2] via 172.22.129.101, 00:00:08, Vlan1
      172.30.0.0/24 is subnetted, 1 subnets
S        172.30.1.0 [1/0] via 172.28.28.254
      172.31.0.0/24 is subnetted, 1 subnets
S        172.31.0.0 [1/0] via 172.28.28.254
S     192.0.0.0/16 [1/0] via 172.28.28.254
      192.168.48.0/32 is subnetted, 1 subnets
S        192.168.48.247 [1/0] via 172.28.28.254
      192.168.84.0/32 is subnetted, 1 subnets
S        192.168.84.247 [1/0] via 172.28.28.254
S     192.168.101.0/24 [1/0] via 172.28.28.254
R     192.168.104.0/24 [120/2] via 172.22.129.101, 00:00:08, Vlan1

 

Router#show ip route connected
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is X.Y.Z.81 to network 0.0.0.0

      10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
C        10.31.129.5/32 is directly connected, Loopback0
      172.22.0.0/16 is variably subnetted, 3 subnets, 2 masks
C        172.22.129.0/24 is directly connected, Vlan1
L        172.22.129.102/32 is directly connected, Vlan1

interface FastEthernet4
 description WAN
 ip address X.Y.Z.82 255.255.255.252
 no ip proxy-arp
 ip flow ingress
 ip nat outside
 ip virtual-reassembly in
 ip tcp adjust-mss 1300
 duplex full
 speed 100
 keepalive 3
 crypto map MYSTREAM-MAP
 hold-queue 224 in
end

Router#show interfaces fastEthernet 4
FastEthernet4 is up, line protocol is up
  Hardware is PQII_PRO_UEC, address is 4403.a738.3c02 (bia 4403.a738.3c02)
  Description: WAN
  Internet address is X.Y.Z.82/30
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (3 sec)
  Full-duplex, 100Mb/s, 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:06, output 00:00:35, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/224/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     26675 packets input, 1826301 bytes
     Received 12230 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog
     0 input packets with dribble condition detected
     44029 packets output, 8969818 bytes, 0 underruns
     0 output errors, 0 collisions, 4 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     3 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

Could you help on this? Or lead me to Tshoot that problem.

By the way the interface 4 is connected to an ISP Modem (TWC in US).

Thanks,

William

 

 

 

6 Replies 6

johnlloyd_13
Level 9
Level 9

hi,

have u tried using other FE ports, changing patch cable to modem and doing an IOS upgrade?

Hi,

 

Thanks for your answer. I've checked the release notes and there is no bug about that.

I think I must use the WAN interface which is fastethernet 4. I'm not able to change the patch cable for now.

What could be the cause?

show version
Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9-M), Version 15.1(4)M4, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Wed 21-Mar-12 00:27 by prod_rel_team

ROM: System Bootstrap, Version 12.4(22r)YB5, RELEASE SOFTWARE (fc1)

Router uptime is 1 week, 3 hours, 6 minutes
System returned to ROM by reload at 08:12:54 UTC Fri Oct 3 2014
System restarted at 08:14:30 UTC Fri Oct 3 2014
System image file is "flash:c880data-universalk9-mz.151-4.M4.bin"
Last reload type: Normal Reload
Last reload reason: Reload Command

 

If you require further assistance please contact us by sending email to
export@cisco.com.

Cisco 881 (MPC8300) processor (revision 1.0) with 236544K/25600K bytes of memory.
Processor board ID FGL1652265J

5 FastEthernet interfaces
1 Virtual Private Network (VPN) Module
256K bytes of non-volatile configuration memory.
125440K bytes of ATA CompactFlash (Read/Write)


License Info:

License UDI:

-------------------------------------------------
Device#   PID                   SN
-------------------------------------------------
*0        CISCO881-K9           FGL1652265J

 

License Information for 'c880-data'
    License Level: advsecurity   Type: Permanent
    Next reboot license Level: advsecurity


Configuration register is 0x2102

 

 

This is an odd situation and I am not sure what would cause this. But I have a couple of suggestions.

- assuming that you have enabled logging buffered (preferable at the level of debugging) can you look through logs since the last time that the interface worked and look for messages about the interface?

- would you post the output of show arp?

- I wonder if changing the keepalive back to the default value would change the behavior.

 

HTH

 

Rick

HTH

Rick

Hi,

I've just enabled the debug external syslog.

Live update:

(o: I set the keepalive to default. And it's back to normal. thank you.

How can keepalive command interfere with arp and others?

Router#show ip arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  X.Y.Z.81            0   c014.3dbb.c4df  ARPA   FastEthernet4
Internet  X.Y.Z.82            -   4403.a738.3c02  ARPA   FastEthernet4
Internet  172.22.129.101         11   c067.af83.88ee  ARPA   Vlan1
Internet  172.22.129.102          -   4403.a738.3bfe  ARPA   Vlan1
Internet  172.22.129.161          6   0015.6547.2c93  ARPA   Vlan1
Internet  172.22.129.193          1   0015.6547.2cde  ARPA   Vlan1
Router#ping X.Y.Z.81
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to X.Y.Z.81, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/5/8 ms
Router#ping X.Y.Z.82
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to X.Y.Z.82, timeout is 2 seconds:
!!!!!

William

William

 

Thanks for posting back and letting us know that setting the keepalive back to its default value did clear up the problem. I do not have an authoritative explanation of why it created the problem but do have a suggestion. So here is my thought process. Keepalive is intended to verify the operating state of the interface and if keepalive can not verify the state of the interface then the interface will not be used. Perhaps the 3 second keepalives was confusing to the modem to which the interface is connected and got the Ethernet into an odd state which was not bad enough to force the interface into the up/down state (usually the outcome when keepalive fails) but was bad enough that the router would not use the interface?

 

HTH

 

Rick

HTH

Rick

Nice one rick!

Thought the crypto map was causing it to fail.

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