topic Re: Nexus 9348 ports speed capability in Server Networking

Nexus 9348 ports speed capability

Sam.Preston — Fri, 18 Oct 2019 12:58:02 GMT

Hello,

I found documentation discrepancy about the ports speed capability of the Nexus 9348GC-FXP.

The datasheet from Cisco is : https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/datasheet-c78-742284.html

This datasheet mentions about the ports configuration:

1) "4 x 10/25-Gbpp SFP28 ports" (see table 2 of the doc)

2) "The 4 ports of SFP28 can be configured as 1/10/25-Gbps" (see figure 3 of the doc)

Both statements above are contradictory. So do these 4 ports support 1-Gbps or not?

I tried to connect a 1-Gbps SFP (which is correctly detected) but the link doesn't come up, despite being serviceable (I have tested on another non-Nexus switch).

Worth mentioning that a "show interface" on the switch gives this output: "Hardware: 1000/10000/25000 Ethernet".

Thanks a lot in advance.

Re: Nexus 9348 ports speed capability

balaji.bandi — Fri, 18 Oct 2019 16:06:13 GMT

Personally I do not believe this support 1GB

9348GC-FXP. - 4 x 10/25-Gbps SFP28 port - as I remember it was not worked for me when i was installed for one of my customers some time back, even though it was detected. If I recall I have to use 10GB for uplink to a parent switch.

(not sure if the things were changed here).

Re: Nexus 9348 ports speed capability

Kirk J — Sun, 20 Oct 2019 23:50:08 GMT

I agree with Balaji.

The 9348GC-FXP specific model does not seem to support 1Gb on those ports.

Kirk...

Re: Nexus 9348 ports speed capability

Kirk J — Mon, 21 Oct 2019 10:16:29 GMT

Spoke with one of the PMs and they noted that the 4p SFP28 can support 1/10/25G.

The datasheet will be updated to reflect that consistently.

Kirk...

Re: Nexus 9348 ports speed capability

balaji.bandi — Mon, 21 Oct 2019 11:38:00 GMT

Good to know "1/10/25G" has support - is this tested ?

Re: Nexus 9348 ports speed capability

Sam.Preston — Wed, 23 Oct 2019 21:43:35 GMT

Thanks a lot for your answers.
Yes I have just tested and I confirm that I was able to make these ports come up at 1-Gbps with 1000BASE-SX transceivers.

Good to know that the documentation will be updated accordingly.

Thanks!

Re: Nexus 9348 ports speed capability

jsbh — Wed, 11 Jun 2025 13:53:10 GMT

Hi @Kirk J

I have the same issue, namely I have also 1000BASE-SX transceivers on Cisco Nexus 9348GC-FXP, Interface eth1/51 (one of the 4 ports) and it is not working fine for me, it actually shows me not connected; however, the other side of the connection, which another router, shows the port as UP!?

Re: Nexus 9348 ports speed capability

Wes Austin — Wed, 11 Jun 2025 14:33:55 GMT

Can you share the running configuration and the interface information for port 1/51?

'show run interface eth1/51'
'show interface eth1/51'
'show interface eth1/51 trans de'

Re: Nexus 9348 ports speed capability

jsbh — Wed, 11 Jun 2025 14:43:16 GMT

In the following find you the outputs:
'show run interface eth1/51':
"!Command: show running-config interface Ethernet1/51
!Running configuration last done at: Wed Jun 11 14:51:31 2025
!Time: Wed Jun 11 16:36:49 2025

version 10.4(4) Bios:version 05.51

interface Ethernet1/51
switchport
switchport access vlan 304
logging event port link-status
no shutdown"

'show interface eth1/51':
"Ethernet1/51 is down (Link not connected)
admin state is up, Dedicated Interface
Hardware: 100/1000/10000/25000 Ethernet, address: 5451.de39.7aaa (bia 5451.de39.7aaa)
MTU 1500 bytes, BW 25000000 Kbit , DLY 10 usec
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, medium is broadcast
Port mode is access
auto-duplex, auto-speed, media type is 1G
Beacon is turned off
Auto-Negotiation is turned on FEC mode is Auto
Input flow-control is off, output flow-control is off
Auto-mdix is turned off
Rate mode is dedicated
Switchport monitor is off
EtherType is 0x8100
EEE (efficient-ethernet) : n/a
admin fec state is auto, oper fec state is auto
Last link flapped never
Last clearing of "show interface" counters never
0 interface resets
Load-Interval #1: 30 seconds
30 seconds input rate 24 bits/sec, 0 packets/sec
30 seconds output rate 0 bits/sec, 0 packets/sec
input rate 24 bps, 0 pps; output rate 0 bps, 0 pps
Load-Interval #2: 5 minute (300 seconds)
300 seconds input rate 0 bits/sec, 0 packets/sec
300 seconds output rate 0 bits/sec, 0 packets/sec
input rate 0 bps, 0 pps; output rate 0 bps, 0 pps
RX
4 unicast packets 6696 multicast packets 16141 broadcast packets
21106 input packets 1470626 bytes
0 jumbo packets 0 storm suppression bytes
0 runts 0 giants 0 CRC 0 no buffer
0 input error 0 short frame 0 overrun 0 underrun 0 ignored
0 watchdog 0 bad etype drop 0 bad proto drop 0 if down drop
0 input with dribble 0 input discard
0 Rx pause
0 Stomped CRC
TX
4 unicast packets 0 multicast packets 0 broadcast packets
4 output packets 2452 bytes
0 jumbo packets
0 output error 0 collision 0 deferred 0 late collision
0 lost carrier 0 no carrier 0 babble 0 output discard
0 Tx pause"

'show interface eth1/51 trans de':

"Ethernet1/51
transceiver is present
type is 1000base-SX
name is CISCO-OPLINK
part number is 1837022038
revision is 01
serial number is OPM28190185
nominal bitrate is 1300 MBit/sec
cisco id is 3
cisco extended id number is 4
cisco part number is 10-2626-03
cisco product id is GLC-SX-MMD
cisco version id is V03

SFP Detail Diagnostics Information (internal calibration)
----------------------------------------------------------------------------
Current Alarms Warnings
Measurement High Low High Low
----------------------------------------------------------------------------
Temperature 29.18 C 89.00 C -9.00 C 85.00 C -5.00 C
Voltage 3.30 V 3.60 V 3.00 V 3.50 V 3.10 V
Current 2.88 mA 12.00 mA 0.50 mA 10.00 mA 1.00 mA
Tx Power -6.03 dBm 0.99 dBm -13.56 dBm -3.00 dBm -9.50 dBm
Rx Power -6.82 dBm 3.99 dBm -21.02 dBm 0.00 dBm -17.01 dBm
Transmit Fault Count = 0
----------------------------------------------------------------------------
Note: ++ high-alarm; + high-warning; -- low-alarm; - low-warning

Re: Nexus 9348 ports speed capability

Wes Austin — Wed, 11 Jun 2025 15:02:30 GMT

Can you adjust the speed manually to 1000 and see if this changes the status?

N9K(config)# int eth1/51
N9K(config-if)# speed
10 1000 100000 2500 40000 5000 800000

Re: Nexus 9348 ports speed capability

jsbh — Wed, 11 Jun 2025 15:20:14 GMT

I had already tested it, it didn't help. I have also put the port to default and reconfigured it again, it didn't also help, putting it in shutdown and then reactivating it again also not helping...

Re: Nexus 9348 ports speed capability

jsbh — Thu, 12 Jun 2025 14:09:04 GMT

Do you possibly have any other ideas?

Re: Nexus 9348 ports speed capability

Wes Austin — Thu, 12 Jun 2025 15:38:19 GMT

I would try to isolate the issue to being the port, SFP, cable, etc.

Is it only the one port that has this behavior?

Is it only one switch that it having the issue?

If you loop back the connection on port 1/51 does the link come up?

Have we tried to swap the SFP on both ends, the cable? Does the issue persist when connecting to all devices at 1G?

Re: Nexus 9348 ports speed capability

jsbh — Fri, 13 Jun 2025 08:38:46 GMT

Is it only the one port that has this behavior? --> No, there are 3 Ports having the issue

Is it only one switch that it having the issue? --> No, there are 3 different switches

If you loop back the connection on port 1/51 does the link come up? --> Not tested yet

Have we tried to swap the SFP on both ends, the cable? --> We can unfortunately not swap the SFP on both sides, because the other side of the connection is the customer port from a provider's router. The cable has been swaped, it didn't also work.

Does the issue persist when connecting to all devices at 1G? --> We have just this 1G with SFP. However, there is another port on one other switch with the same model and same port number and there it works, the configurations and SFPs are also the same.