Thank you for asking this question in the support community. Currently, ADTRAN does not recommend using R10.11.0 firmware on the NetVanta 1638 if you are utilizing the ActivChassis feature; however, if you are not using ActivChassis, then R10.11.0 is fine. If you are using ActivChassis, then ADTRAN recommends R10.10.0 (which is the minimum requirement for the IGMP Snooping feature). Here is a note on the subject: AOS R10.11.0 released for the NetVanta 1500/1600 Series
Furthermore, ADTRAN recommends using the extended maintenance release, unless a new feature is required. ADTRAN will identify an extended maintenance release approximately once a year. In these extended maintenance releases, bugs will continue to be addressed but no new features will be added (separate ongoing feature releases will continue to be made available). Our plan is to periodically release extended maintenance builds with bug fixes throughout the year, until the next extended maintenance release is identified.
Unless there is a specific feature needed in a later feature release, ADTRAN recommends using the latest extended maintenance release for your AOS product. The current Extended Maintenance Release is R10.9.
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