Line Protocol Flapping
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
08-28-2012 02:29 AM - edited 03-07-2019 08:34 AM
Hi all,
been having an ongoing issue with a particular site having one of the devices line protocol flapping.
I work for a Wireless ISP and the device impacted is the back haul radio into the site. I have swapped from a 2950T to a 3550. Replaced the radio, PoE, patch lead. We have re ran the cable up the tower using shielded outdoor cable with a drain wire which has been earthed to an earthing block in the cabinet.
We have other devices on the tower not experiencing the issue. We suspect cable interference however am now at a loss to diagnose further. If anyone can suggest further troubleshooting at the switch level it would be appreciated.
Please see diagnostics so far:
Aug 28 17:37:09.563 AEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up
Aug 28 18:22:40.563 AEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down
Aug 28 18:22:42.567 AEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up
Aug 28 18:45:15.923 AEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down
Aug 28 18:45:17.927 AEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to up
QLD-SBK-3550#show int fa0/7
FastEthernet0/7 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 000e.83f9.3287 (bia 000e.83f9.3287)
Description: RM5+RD30 to HQ Building
MTU 1546 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 2/255, rxload 4/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:15, output 01:43:38, 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: 0/40 (size/max)
5 minute input rate 1745000 bits/sec, 421 packets/sec
5 minute output rate 1107000 bits/sec, 409 packets/sec
1132370184 packets input, 4139538864 bytes, 0 no buffer
Received 9667975 broadcasts (0 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 2117081 multicast, 0 pause input
0 input packets with dribble condition detected
1068411398 packets output, 3034028216 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
QLD-SBK-3550#show int fa0/7 counters
Port InOctets InUcastPkts InMcastPkts InBcastPkts
Fa0/7 674154638736 1122703246 2117081 7550914
Port OutOctets OutUcastPkts OutMcastPkts OutBcastPkts
Fa0/7 402466413143 1067069897 116175 1226488
QLD-SBK-3550#show int fa0/7 counters error
Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize
Fa0/7 0 0 0 4 0
Port Single-Col Multi-Col Late-Col Excess-Col Carri-Sen Runts Giants
Fa0/7 0 0 0 0 0 0 0
QLD-SBK-3550#show int fa0/7 counters protocol status
Protocols allocated:
FastEthernet0/7: Other, IP
QLD-SBK-3550#show int fa0/7 stats
FastEthernet0/7
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 67 4020
Route cache 0 0 0 0
Total 0 0 67 4020
QLD-SBK-3550#show int fa0/7 status
Port Name Status Vlan Duplex Speed Type
Fa0/7 RM5+RD30 to HQ Bui connected trunk a-full a-100 10/100BaseTX
- Labels:
-
Other Switching
.png)
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
09-01-2012 11:24 PM
Hi Dylan,
If the line protocol is down, the line protocol software processes have determined that the line is unusable.
The line protocol Up/Down indicates that while the phsyical line is good - meaning you're seeing that there is a device connected at the other side, but it is not negotiating the link successfully
- This could be caused by a unidirectional link of some type
- A hardware/software failure on the switch, or the other side could be err-disabled or shutdown on the other side.
- This could also be a problem if different protocols are used for trunking(ISL vs dot1q).
Perform the following corrective actions:
- Replace the cable.
- Check the local and remote interface for misconfiguration.
- The local interface Fa0/7 is config as trunk port, please check the config on other end interface
- check the speed / duplex settings on both end (try to hard core both end or config as auto)
Regards,
Aru
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
09-01-2012 11:32 PM
Would be nice if you have a 3750G/E/X or a 2960G/S then things could get mighty interesting if you run TDR with the switch models I've mentioned.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
09-01-2012 11:55 PM
Thanks for the replies
As it is a commercial tower there are many providers and a wide variety of device s on site so it is difficult to be 100% certain on the root cause or the offending device but in the end we relocated our radio to a different spot on the tower where there is less devices and as a result the interface is no longer flapping so I suspect that another provider has some damaged or faulty equipment that is leaking onto the tower resulting in the cable interference we were experiencing. very difficult issue to identify with no errors or real give aways.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
04-12-2017 02:46 PM
In case others have this, we had an issue and it turned out to be a faulty patch cable. Either cable test your cables if you have this issue or change them out.
