Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

Forum Discussion

johnbernardcheu's avatar
johnbernardcheu
Icon for Cirrus rankCirrus
Oct 20, 2017

TCP Max Segment Size(MSS) and Path MTU Discovery question

Hi there,does PATH MTU take precedence over the MSS MTU? Thanks!

 

2 Replies

  • james_lee_31100's avatar
    james_lee_31100
    Icon for Nimbostratus rankNimbostratus
    Oct 23, 2017

    It Depends, if MSS MTU is smaller, it will cause chatty communication

     

    If Oversized MSS, it will generate can't fragment ICMP

     

    F5 LTM will detect client path MTU with following command

     

    tmsh show net cmetrics

     

    • johnbernardcheu's avatar
      johnbernardcheu
      Icon for Cirrus rankCirrus
      Oct 27, 2017

      So if MSS is configured for 536 and path MTU is 1500, what is the max MSS...is it 536 or 1460?