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ex-3300 aging time and show ethernet-switching table

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  • 1.  ex-3300 aging time and show ethernet-switching table

    Posted 06-22-2020 07:16

    Hi All,

    I would like to understand how to read the value "Age" when I run the command show ethernet-switching table on ex-3300.

    From here: https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/mac-table-aging-time-bridging.html

     

    Default
    Entries remain in the Ethernet switching table for 300 seconds.

    Now, if i run the command

    show ethernet-switching table vlan 123
    

    I see for example

    show ethernet-switching table vlan 123
    Ethernet-switching table: 82 unicast entries
      VLAN              MAC address       Type         Age    Interfaces
      vlan123           *                 Flood                            - All-members
      vlan123           00:xx:xx:xx:xx:xx Learn            0           xe-0/1/2.0
      vlan123           00:yy:yy:yy:yy:yy Learn          0          xe-0/1/2.0
    

    The "Age" field is set to 0 but the mac-address 00:xx:xx:xx:xx:xx seems to me that is not removed from mac addrees table and keep on appearing in the above output.

    Reading documentation i was expecting that the switch after 300 second is simply removing the mac that so is considered inactive so i would not see it again the ethernet-swithcing table output. Am I missing something?

     

    Thanks.



  • 2.  RE: ex-3300 aging time and show ethernet-switching table

     
    Posted 06-22-2020 08:01

    While I don't have any solution for this, there was a similar Juniper Forum entry in the past:

    https://forums.juniper.net/t5/Ethernet-Switching/EX4500-mac-table-grows-to-limit-all-mac-ages-are-0/td-p/311678

     

    I've checked the same on my QFX5100 and EX4300-48MP, but on both the "Age" entry is always "-".

     

    I don't know which JunOS version you have installed, but you can try with the latest one if possible, which would be 15.1R7-S7.

     

    Please note that EX3300 is EOL announced and receives new JunOS releases (security fixes only) until mid-2022 only.



  • 3.  RE: ex-3300 aging time and show ethernet-switching table

    Posted 06-22-2020 08:12

    Hello FabNewCert,

     

    Greetings !!

     

    Juniper Networks EX Series Ethernet Switches store MAC addresses in the Ethernet switching table, also called the MAC table. When the aging time for a MAC address in the table expires, the address is removed.

    To Know about the Mac table Aging I hope the below Docs helps on EX series switches 

     

    https://www.juniper.net/documentation/en_US/junos/topics/topic-map/mac-table-aging.html#id-configuring-mac-table-aging-on-switches

     

    Please mark "Accepted Solution" if this helps you.

    Kudos are always appreciated!

     

     

    Regards,

    Deeksha P

     

     



  • 4.  RE: ex-3300 aging time and show ethernet-switching table

    Posted 06-22-2020 08:57

    Hi deeksha thanks for the answer but the info you provided are excatly the same that i wrote in my original post.



  • 5.  RE: ex-3300 aging time and show ethernet-switching table

    Posted 06-22-2020 09:28

    Hi FabNewCert,

     

    Greetings, 

     

    As per my understanding you seem to have persistent-learning enabled. Ideally this behaviour is seen when we have the persistent-learning enabled. Refer the link for more details: Understanding Persistent MAC Learning (Sticky MAC) 

    > show ethernet-switching table
    Ethernet-switching table: 8 entries, 2 learned, 5 persistent entries
      VLAN              MAC address       Type         Age Interfaces
      default           *                 Flood          - All-members
      default           00:10:94:00:00:02 Persistent        0 ge-0/0/42.0
      default           00:10:94:00:00:03 Persistent        0 ge-0/0/42.0
      default           00:10:94:00:00:04 Persistent        0 ge-0/0/42.0
      default           00:10:94:00:00:05 Persistent        0 ge-0/0/42.0
      default           00:10:94:00:00:06 Persistent        0 ge-0/0/42.0
      default           00:21:59:c8:0c:50 Learn             0 ae0.0 >> Age shows up as 0 
      default           02:21:59:c8:0c:44 Learn             0 ae0.0 >> These entries are preserved even after a reboot

    Per my understanding, these entries might be persistent and that's why they show up as 0 in the timer as they are bound to the interface and preserved even after reboot.

    Try and use the clear ethernet-switching table command to clear the persistent MAC address entry from the interface.

    Hope this helps. Smiley Happy

     

    Please mark "Accept as solution" if this answers your query. 

    Kudos are appreciated too! 

     

    Regards, 

    Sharat Ainapur



  • 6.  RE: ex-3300 aging time and show ethernet-switching table

     
    Posted 06-22-2020 09:53

    Hi 

     

     

    Juniper Networks EX Series Ethernet Switches store MAC addresses in the Ethernet switching table, also called the MAC table. When the aging time for a MAC address in the table expires, the address is removed.

     

    If your switch runs Juniper Networks Junos operating system (Junos OS) for EX Series switches with support for the Enhanced Layer 2 Software (ELS) configuration style, you can configure the MAC table aging time on all VLANs on the switch. If your switch runs Junos OS that does not support ELS, you can configure the MAC table aging time on all VLANs on the switch or on specified VLANs, as well as configure aging time to be unlimited, either on all VLANs or on specified VLANs, so that MAC addresses never age out of the table.

     

    For better understanding please go through the below documents 

     

    https://www.juniper.net/documentation/en_US/junos/topics/topic-map/mac-table-aging.html

     

    https://www.juniper.net/documentation/en_US/junos/topics/example/layer-2-mac-limit-port-security-configuring.html

     

    If I clear the mac table it ends up being about 5000 entries, and it continuouosly grows up to the 32k limit unless I clear it again.

     

    Please mark "Accepted Solution" if this helps.

    Kudos are always appreciated

     

    Thanks 

    Suraj



  • 7.  RE: ex-3300 aging time and show ethernet-switching table
    Best Answer

     
    Posted 06-23-2020 02:57

    I don't think you are missing anything.  Assuming you checked that you don't have any overrides configured for mac aging the behavior should be as you note removing after 5 minutes.

     

    So this is likely a bug which Juniper calls PR (problem reports).  Upgrading to the current release chain and seeing if the issue clears would be a possible step.  Fortunately this type of bug is not likely to be service affecting.

     

    There is also a public PR search database where you could look for this bug and confirm which release it is fixed in if already known.

     

    And naturally, you could open a case and have JTAC to the search and check for you as well.

     



  • 8.  RE: ex-3300 aging time and show ethernet-switching table

    Posted 06-25-2020 08:41

    no overrides configured.

    Thanks as usual to you!