Cisco Catalyst SD-WAN Network Configuration Guide, Releases 26.x and Later

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Verify TCP MSS and dont clear fragment configurations

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Outlines verification steps to confirm TCP MSS and don't clear fragment configurations, detailing command outputs and expected results to validate correct implementation.


TCP MSS configuration

The following is sample output of the show platform hardware qfp active feature sdwan datapath session summary command:


Device# show platform hardware qfp active feature sdwan datapath session summary

Src IP          Dst IP          Src Port Dst Port   Encap    Uidb     Bfd Discrim PMTU                                                                           
------          ------          -------- -------    ------   -------  ----------- -----                                                                          
10.1.15.25      10.1.14.14      12347    12346      IPSEC    65526    10007       1446                                                                           
10.1.15.25      10.0.5.21       12347    12357      IPSEC    65526    10009       1446                                                                           
10.1.15.25      10.0.5.11       12347    12347      IPSEC    65526    10008       1446                                                                           
10.1.15.25      10.1.16.16      12347    12366      IPSEC    65526    10006       1446                                                                           

Dont fragment configuration

The following is sample output of the show platform software interface rp active name Tunnel1 command to verify if Clear-dont-fragment is enabled or not.


Device# show platform software interface rp active name Tunnel1 | include dont
IP Clear-dont-fragment: TRUE

The following is sample output of the show running-config interface Tunnel1 command that displays the running configuration when Clear-dont-fragment is enabled.


Device# show running-config interface Tunnel1
Building configuration...
    
Current configuration : 132 bytes
!
interface Tunnel1
ip unnumbered GigabitEthernet1
ip clear-dont-fragment
tunnel source GigabitEthernet1
tunnel mode sdwan
end