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Don't forget Layer 1!

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  • 1.  Don't forget Layer 1!

    Posted Aug 20, 2021 05:37 AM

    Setting the Scene

    For a while I had been having inexplicable, intermittent issues with the access point plugged into my switch. The switch is a CX6300M that supports SmartRate (aka Multigig). This is a good thing, because the local AP is an AP515, with support for a 2.5Gb connection.

    The Components

    ⦁ Aruba 6300M 48SR5 CL6 PoE 4SFP56 Switch (JL659A)
    ⦁ Aruba AP-515 (RW) Unified AP (Q9H62A)
    ⦁ Central is used to manage all switches and APs, including these

    Symptoms

    Some of the symptoms that I noticed:
    • Wireless devices would occasionally have connectivity of throughput issues
    • Devices would sometimes be unexpectedly connected to APs other than the 515
    • AI insights reported higher than normal errors (like DHCP or DNS)
    • Problems were intermittent, and not readily reproducible

    These switch event log entries were the most consistent indicator that something unusual was going on. These are all from port 1/1/26 - the AP515:
    2021-07-03T11:28:25.291053+10:00 bvcore-6300 lldpd[3329]: Event|106|LOG_INFO|MSTR|1|LLDP neighbor 24:62:ce:cc:6d:22 deleted on 1/1/26
    2021-07-03T11:26:45.347769+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T11:26:41.573630+10:00 bvcore-6300 poe-protod[3319]: Event|7905|LOG_INFO|MSTR|1|Powered device disconnected on interface 1/1/26
    2021-07-03T11:26:41.210722+10:00 bvcore-6300 intfd[652]: Event|404|LOG_INFO|UKWN|1|Link status for interface 1/1/26 is down
    2021-07-03T11:26:37.267789+10:00 bvcore-6300 intfd[652]: Event|403|LOG_INFO|UKWN|1|Link status for interface 1/1/26 is up
    2021-07-03T11:26:32.396348+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T11:26:32.142903+10:00 bvcore-6300 intfd[652]: Event|404|LOG_INFO|UKWN|1|Link status for interface 1/1/26 is down
    2021-07-03T11:26:25.309276+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T11:26:14.017325+10:00 bvcore-6300 intfd[652]: Event|403|LOG_INFO|UKWN|1|Link status for interface 1/1/26 is up
    2021-07-03T11:26:09.177683+10:00 bvcore-6300 intfd[652]: Event|404|LOG_INFO|UKWN|1|Link status for interface 1/1/26 is down


    Event ID 5511 is a good example for the link up/down.
    bvcore-6300# show event -a -r -e 5511 | in 1/1/26
    2021-07-03T11:26:45.347769+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T11:26:32.396348+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T11:26:25.309276+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T11:00:53.314973+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T11:00:45.299778+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T10:58:03.307378+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T10:57:45.364306+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T10:36:28.301364+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T10:36:20.304822+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T10:35:28.314502+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T10:35:20.313240+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T10:33:48.293762+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T10:33:40.318406+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down
    2021-07-03T10:33:08.318124+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link came up
    2021-07-03T10:33:00.298939+10:00 bvcore-6300 hpe-policyd[3602]: Event|5511|LOG_WARN|AMM|-|Interface 1/1/26 Link gone down


    Troubleshooting


    I found a new Cat6 cable, and decided to install that instead - maybe the higher quality/increased frequency spec would work better with the 2.5Gb connection. And it did!

    With the AP515 now on port 1/1/25 for the past six weeks:
    bvcore-6300# show event -r -e 5511 | in 1/1/25

    No errors!

    Apart from the regular LLDP neighbour messages, nothing at all!
    bvcore-6300# show event -r | in 1/1/25
    :
    2021-07-03T11:28:34.493665+10:00 bvcore-6300 lldpd[3329]: Event|105|LOG_INFO|MSTR|1|LLDP neighbor 24:62:ce:cc:6d:22 updated on 1/1/25
    2021-07-03T11:28:11.209651+10:00 bvcore-6300 lldpd[3329]: Event|105|LOG_INFO|MSTR|1|LLDP neighbor 24:62:ce:cc:6d:22 updated on 1/1/25
    2021-07-03T11:27:40.405618+10:00 bvcore-6300 lldpd[3329]: Event|104|LOG_INFO|MSTR|1|LLDP neighbor 24:62:ce:cc:6d:22 added on 1/1/25
    2021-07-03T11:27:35.480595+10:00 bvcore-6300 hpe-mvrpd[3290]: Event|3101|LOG_INFO|MSTR|1|MVRP enabled on port 1/1/25
    2021-07-03T11:27:34.403729+10:00 bvcore-6300 intfd[652]: Event|403|LOG_INFO|UKWN|1|Link status for interface 1/1/25 is up
    2021-07-03T11:26:47.564129+10:00 bvcore-6300 poe-hald[3341]: Event|7902|LOG_INFO|MSTR|1|Powered device power delivery on interface 1/1/25
    2021-07-03T11:26:47.559817+10:00 bvcore-6300 poe-protod[3319]: Event|7901|LOG_INFO|MSTR|1|Detected powered device on interface 1/1/25. Type:3, Class:5


    Conclusion

    Higher speed connections like 2.5 and 5Gb for APs are becoming more common now - don't skimp on the patch leads.

    Network troubleshooting should always start at Layer 1 - the physical layer - and work up from there. Jumping on the CLI or NMS is nearly always where people start, and with good reason. However, then it is easy to forget Layer 1, especially if it has worked for a long time. However, you will occasionally have to go back and verify it. Don't forget Layer 1!

    ------------------------------
    Richard Litchfield
    Airheads MVP 2020, 2021
    ------------------------------


  • 2.  RE: Don't forget Layer 1!

    Posted Aug 22, 2021 07:51 AM
    Hi,

    Yes in theory Cat5e works for 2.5G but it really depend on cable quality and distance so Cat6 is really recommended :)

    ------------------------------
    Laurent from Brest / France
    Network Engineer
    ------------------------------



  • 3.  RE: Don't forget Layer 1!

    Posted Aug 22, 2021 11:24 AM
    Hi @RL66, just a clarification: was the Aruba AP-515 directly connected into the Aruba CX 6300M switch with just a Cat. 5E Patch Cord?​ no other cabling involved?

    ------------------------------
    Davide Poletto
    ------------------------------



  • 4.  RE: Don't forget Layer 1!

    Posted Aug 23, 2021 12:50 AM
    Yes, directly connected, approx 1.5m cable. For that short distance, it really should have worked - and it mostly did - but not well enough.

    PS: Not sure where the RL66 came from - that was not my username last week!

    ------------------------------
    Richard Litchfield
    Airheads MVP 2020, 2021
    ------------------------------



  • 5.  RE: Don't forget Layer 1!

    Posted Aug 23, 2021 03:18 AM
    Hi Richard, indeed this enforce what I was lately thinking: a good Cat. 6 UTP/FTP patch cable (or a certified Cat. 6 UTP/FTP cabling system providing end-to-end connectivity) should be the way to go for any speed > 1 Gbps...even if documents say that up to 5 Gbps speed is supported on Cat. 5E cabling.

    With regard to user's alias: have you ever noticed that referencing a Community user in a post by his/her alias (by prepending it with @) doesn't work at all?​​​​

    ------------------------------
    Davide Poletto
    ------------------------------



  • 6.  RE: Don't forget Layer 1!

    Posted Aug 25, 2021 05:05 AM
    Thanks Richard for feedback and doc about cable length ;)

    ------------------------------
    PowerArubaSW : Powershell Module to use Aruba Switch API for Vlan, VlanPorts, LACP, LLDP...

    PowerArubaCP: Powershell Module to use ClearPass API (create NAD, Guest...)

    PowerArubaCL: Powershell Module to use Aruba Central

    PowerArubaCX: Powershell Module to use ArubaCX API (get interface/vlan/ports info)..

    ACEP / ACMX #107 / ACDX #1281
    ------------------------------