Re: GigabitEthernet1/1 is up, line protocol is down (notconnect)

fabio.marino · ‎02-09-2014

Hi All,

I am really curious to investigate a possible reason behind this error message.

During the configuration of a port channel bundled with 2 links I have the error in the subject but only for one side of the connection and only for one link part of the port channel.

On the other side the corrispondent interface was up/up and the other link part of the port channel was able to go up with no issue (for all the configuration is the same).

Background info:

- The link in discussion was connecting the two Multilayer swicthes before the configuration of the port channel with no issue

- The port channel is a L2 etherchannel

- What was done was simply to shutdown the interface on both swicthes, add the command channel group xx mode on on both side of the connection and then bring up the connection with the result above showed: one side up/down (not connect) and the other side up/up

I am excluding problem with the configuration. The reason is simple: i just reply the configuration to the all links (total 2) part of the port channel with no issue.

Can be a cabling problem (SFP)? Again keep in mind that before the change, this link was active with no issue for 4 years.

Thanks all.

Peter Paluch · ‎02-09-2014

Hi Fabio,

Nice to hear from you again

On the switch that has the Gi1/1 port in up/down state, can you please post the outputs of these commands in their entirety?

show etherchannel summary

show int gi1/1

show int gi1/1 capa

show int status err-disabled

I think this could theoretically be a cabling problem, although modern SFPs should be able to report uni-directional link condition and pull the entire link down on both ends.

Looking forward to seeing the command outputs.

Best regards,

Peter

fabio.marino · ‎02-12-2014

Hi Peter,

Find below the requested output.

I forgot to mention something:

The etherchannel is a L2
The mode employed to create the port channel was on

In any case what I did in the meanwhile was:

- To check the cable -> It is ok

- I did not check the SFP but I configured the involved interfaces as L3 and I bringed up both with no issue. They are connected so I am assuming that the SFP is ok. Do you agree?

At this point due to the fact that:

Configuration is working properly for the second link part of the same portchannel
The cable and sfp is ok
The only problem that I can see here is the Etherchannel Modes adopted: I heard that on modes is not the best practice. The best is use the LACP

Here the requested output:

show int gi1/1 capa

Dot1x:                 yes
Model:                 WS-X6748-SFP
Type:                  1000BaseSX
Speed:                 1000
Duplex:                full
Trunk encap. type:     802.1Q,ISL
Trunk mode:            on,off,desirable,nonegotiate
Channel:               yes
Broadcast suppression: percentage(0-100)
Flowcontrol:           rx-(off,on,desired),tx-(off,on,desired)
Membership:            static
Fast Start:            yes
QOS scheduling:        rx-(1q8t), tx-(1p3q8t)
CoS rewrite:           yes
ToS rewrite:           yes
Inline power:          no
SPAN:                  source/destination
UDLD                   yes
Link Debounce:         yes
Link Debounce Time:    yes
Ports on ASIC:         25,27,29,31,33,35,37,39,41,43,45,47
Port-Security:         yes

GigabitEthernet1/1 is up, line protocol is down (notconnect)
Hardware is C6k 1000Mb 802.3, address is 0019.aa70.0000 (bia 0019.aa70.0006)
Description:
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is SX
input flow-control is off, output flow-control is off
Clock mode is auto
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:58, output 02:08:13, output hang never
Last clearing of "show interface" counters 4y10w
Input queue: 0/2000/66318/0 (size/max/drops/flushes); Total output drops: 1731225685
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 17000 bits/sec, 25 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
     1705750435550 packets input, 2106584160022948 bytes, 1 no buffer
     Received 245618852 broadcasts (148781910 multicasts)
     0 runts, 48 giants, 1 throttles
     0 input errors, 0 CRC, 0 frame, 66317 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     3762458417011 packets output, 3133012553118384 bytes, 0 underruns
     0 output errors, 0 collisions, 4 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

show interfaces status err-disabled
empty

show etherchannel summary
120 Po120(SU) - Gi1/2(P) Gi1/1(D)

Leo Laohoo · ‎02-12-2014

What is connected to the to Gi 1/1?

If this is another switch, can you please post the output to the command "sh interface "?

fabio.marino · ‎02-12-2014

Hi Leo,

Connection is between 6500 (Gi 1/1 interface up/down) and 3750 (Gi 1/0/1 interface up/up).

The output of the other interface Gi1/0/1 on the 3750, is not available but it was interface up/up.

Leo Laohoo · ‎02-12-2014

5 minute input rate 17000 bits/sec, 25 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

Clear the counters.

If this isn't a faulty SFP, then this could be a bug. I have never seen this before.

fabio.marino · ‎02-12-2014

Guys I read something that may be can be related to this issue.

In the interface Gi1/1 was active a SPAN session. Traffic from this interface was monitored.

I read in a different blog that

The interfaces in a port channel must share the same speed and duplex, trunking encapsulation(if not trunking – the same access vlan), the same STP cost per per VLAN, and no ports can have SPAN configured.

What do you think?

Moreover I will share here what was the MST cost of the port-channel at boht end of the link

Cat6500#show spanning-tree interface port-channel 31

Mst Instance Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
MST1 Desg FWD 20000 128.1674 P2p

Cat3750#show spanning-tre interface port-channel 31

Mst Instance Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
MST1 Root FWD 10000 128.704 P2p

So, from one side of the port-channel I had cost 20000 (only one port bundled in the port channel) whereas on the other side the port channel show two bundled links (cost 10000).

This again confirm that one side of the port channel appear to have two links the other one only one.

fabio.marino · ‎02-13-2014

In any case I cross check the matter of the span matter.

An EtherChannel interface that is configured as a Switched Port Analyzer (SPAN) destination port does not join the group until it is deconfigured as a SPAN destination port

In my case the interface was the source so no relation with the described fault.