Cisco C1000 Port Taking long to come up with device connected

nikkadim · ‎03-29-2022

Have a Cisco Catalyst C1000 (15.2(7)E4) and custom IoT devices. Sometimes it could take 10 minutes to get a link, sometimes even after an hour - nothing.

Devices are works fine with older Catalyst switches.

Config for the C1000:

spanning-tree mode rapid-pvst
spanning-tree extend system-id
switchport mode access (per port)
spanning-tree portfast edge (per port)

Any help is appreciated

pieterh · ‎03-30-2022

please give more information about the "older Catalyst switches" port settings and the device involved
if the other device is a switch or router then it's settings may not match the "switchport mode access" on the c1000

could also be something in speed/duplex settings of the device versus the port?
spanning-tree has no influence on link up/down , as it will have on packet forwarding
and what information can you find in the console logging?

nikkadim · ‎03-30-2022

Thank you @pieterh

old Catalyst switches are WS-C3750G-48TS, port setting just "switchport mode access", global settings in them:

spanning-tree mode rapid-pvst
spanning-tree portfast default
spanning-tree extend system-id

speed/duplex on device is in Auto, switch also has it in Auto

Interface status:

GigabitEthernet1/0/5 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 3037.a6aa.9905 (bia 3037.a6aa.9905)
MTU 9000 bytes, BW 100000 Kbit, 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, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, 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: 6801
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 71000 bits/sec, 56 packets/sec
9870706 packets input, 632991942 bytes, 0 no buffer
Received 53429 broadcasts (0 multicasts)
0 runts, 0 giants, 0 throttles
1 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
78964603 packets output, 10754282479 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

@pieterh wrote:
spanning-tree has no influence on link up/down , as it will have on packet forwarding

https://community.cisco.com/t5/switching/port-taking-long-to-come-up/td-p/2346952

that is the reason I started looking into STP

Could you suggest please, what exactly I need to look at in console logging?

pieterh · ‎03-31-2022

that is the reason I started looking into STP

Yes!, but you've already configured "spanning-tree portfast edge "
with this the port does not wait with packet forwarding until all states (blocking, listening, learning, forwarding)
but goes directly into forwarding state

At least! if this is an EDGE port (that is no switch connected)

Interface status:

.....

Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
so the connected device is either not capable of 1Gb or it is set to fixed ?
if fixed then it will be better to match the setting of the switchport to "speed 100" instead of auto
also check your cabling, are all 8 wires (4 pairs) correctly wired or do you use 4 wires (2 pair)?

what exactly I need to look at in console logging?

start with anything logged for this interface, from the time you plug in the cable, until the link comes up

show logging | include 1/0/5 ! (for interface GigabitEthernet1/0/5 )

maybe this logging will show that PoE (Power over Ethernet) is contributing to the error

nikkadim · ‎03-31-2022

@pieterh , connected IoT device has 100Mb/s interface and works fine with NIC (in PC) in Auto mode and C3750 in auto speed/duplex. The only problem we have with C1000 Catalyst in auto speed/duplex mode. When Port on C1000 switched to 100Mbit/s all works fine.