Forum Discussion

Sean_Youngberg_'s avatar
Sean_Youngberg_
Icon for Nimbostratus rankNimbostratus
Sep 16, 2013

ToS getting reset to 0 when egress from LTM

Scenario:

 

Micrsoft Lync front-end servers. Their gateway is on the LTM. Client requests to the front-end are balanced by virtual servers on a variety of ports.

 

The Lync servers are configured to mark their SSL-TLS SIP traffic (port 5061) as AF31. From packet captures, I have found that the markings are in tact while traversing the link to the LTM back-end network. However, when getting capture from the front-end interfaces, the DSCP has been reset to 0.

 

I have a TCP profile set on the virtual server that is listening on 5061, which has the options enabled to pass-through ToS and QoS. What else am I missing here?

 

I found a bug that looks somewhat related, but I am not running a SIP profile and this traffic is TCP.

 

http://support.f5.com/kb/en-us/solutions/public/14000/000/sol14019.html

 

deployment
microsoft
qos
tcp profile
tos

6 Replies

Sort By
  • What_Lies_Bene1's avatar
    What_Lies_Bene1
    Icon for Cirrostratus rankCirrostratus
    Sep 16, 2013

    Could be another bug. I wonder, are the Pool IP ToS setting also set to Pass Through. They should be as it's the default. I've no idea if they take precedence or not unfortunately although this suggests the TCP profile does.

     

    You might also try setting the value to 65535 although it seems like a very old solution.

     

  • Sean_Youngberg_'s avatar
    Sean_Youngberg_
    Icon for Nimbostratus rankNimbostratus
    Sep 16, 2013

    I verified that Pool settings are all correctly set to Pass Through. I suppose I will next try to set the ToS value in the TCP profile instead of using Pass Through.

     

    • boneyard's avatar
      boneyard
      Icon for MVP rankMVP
      Sep 17, 2013
      personally i would raise a ticket with F5 support, if it is a bug they will get it fixed.
    • What_Lies_Bene1's avatar
      What_Lies_Bene1
      Icon for Cirrostratus rankCirrostratus
      Sep 17, 2013
      I'd agree that a ticket with F5 would be beneficial to you and others.
    • Sean_Youngberg_'s avatar
      Sean_Youngberg_
      Icon for Nimbostratus rankNimbostratus
      Sep 17, 2013
      I have a case started. I will update this question with the outcome. Thanks!