Cisco Router Interface Issue

AI99 · ‎05-17-2018

Hello,

I have a CISCO1921 router. The interface G0/0 is connected to a WAN modem dedicated for a layer 2 site to site connection. The connectivity to remote site (172.20.90.2/24) occasionally goes down.

Below is the interface config and statistics. Any hints ?

Thanks.

Config:

!
interface GigabitEthernet0/0
 description G0/0-WAN
 ip address 172.20.90.3 255.255.255.0
 no ip proxy-arp
 ip authentication mode eigrp 10 md5
 ip authentication key-chain eigrp 10 eigrp-keys
 duplex auto
 speed auto

Interface Statistics:

MAIN-RT#show interfaces g0/0            
GigabitEthernet0/0 is up, line protocol is up 
  Hardware is CN Gigabit Ethernet, address is 30f7.0d99.7780 (bia 30f7.0d99.7780)
  Description: G0/0-WAN 
  Internet address is 172.20.90.3/24
  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 (10 sec)
  Full Duplex, 100Mbps, media type is RJ45
  output flow-control is XON, input flow-control is XON
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:02:38, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 323
  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
     541677827 packets input, 2252707648 bytes, 0 no buffer
     Received 13 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     600083342 packets output, 2788903018 bytes, 0 underruns
     0 output errors, 0 collisions, 21 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     18 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

johnlloyd_13 · ‎05-17-2018

hi,

can you try to hard code g0/0 to 100/full and observe?

AI99 · ‎05-17-2018

Didn't work. I also tried shut - no shut the interface after changing config:

!

interface GigabitEthernet0/0
description G0/0-WAN
ip address 172.20.90.3 255.255.255.0
no ip proxy-arp
ip authentication mode eigrp 10 md5
ip authentication key-chain eigrp 10 eigrp-keys
duplex full
speed 100
end

!

MAIN-RT#sh int g0/0
GigabitEthernet0/0 is up, line protocol is up
Hardware is CN Gigabit Ethernet, address is 30f7.0d99.7780 (bia 30f7.0d99.7780)
Description: G0/0-WAN
Internet address is 172.20.90.3/24
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 (10 sec)
Full Duplex, 100Mbps, media type is RJ45
output flow-control is unsupported, input flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:01:54, output 00:00:04, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 323
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
     541677827 packets input, 2252707648 bytes, 0 no buffer
     Received 13 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     600083581 packets output, 2788923099 bytes, 0 underruns
     0 output errors, 0 collisions, 22 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     18 lost carrier, 0 no carrier, 0 pause output
     0 output buffer failures, 0 output buffers swapped out

AI99 · ‎05-17-2018

CISCO881 Router - also connected to a WAN modem
!
interface FastEthernet4 (also connected to a WAN modem)
description F4-WAN
ip address 172.20.90.2 255.255.255.0
no ip proxy-arp
ip authentication mode eigrp 10 md5
ip authentication key-chain eigrp 10 eigrp-keys
ip virtual-reassembly in
duplex auto
speed auto

REMOTE-RT#sh int f4
FastEthernet4 is up, line protocol is up
Hardware is PQII_PRO_UEC, address is e02f.6dcc.2569 (bia e02f.6dcc.2569)
Description: F4-WAN
Internet address is 172.20.90.2/24
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 (10 sec)
Full-duplex, 100Mb/s, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 4
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
     597099205 packets input, 762830048 bytes
     Received 22598 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
     551570817 packets output, 4076380128 bytes, 0 underruns
     0 output errors, 0 collisions, 19 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     23 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out

Georg Pauwen · ‎05-18-2018

Hello,

--> 18/23 lost carrier, 0 no carrier, 0 pause output

That usually indicates bad cabling...check for that and try and replace the cables...