A FIPS-mode node cannot be upgraded while its IPsec policies use Diffie-Hellman groups 1, 2 or 5. Those policies must be reconfigured with groups 14 to 18 first, and groups 17 and 18 are unavailable from 15SU3.

Checked 2026-09-25

Vendor
Cisco
Product
Unified Communications Manager
Subsystem
FIPS / IPsec
Deployment
on-premises
Region
not restricted
Release range
destination Release 15; DH 17/18 removal from 15SU3
Checked
2026-09-25

Sources

Cite this note

APA

WarmTransfer. (2026, September 25). Planning a Unified CM upgrade: source note cucm-upgrade-planning-fips-dh-groups. WarmTransfer. https://warmtransfer.net/knowledge/claims/cucm-upgrade-planning-fips-dh-groups

BibTeX

@misc{warmtransfer-claim-cucm-upgrade-planning-fips-dh-groups,
  title  = {Planning a Unified CM upgrade: source note cucm-upgrade-planning-fips-dh-groups},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/claims/cucm-upgrade-planning-fips-dh-groups},
  note   = {Source note cucm-upgrade-planning-fips-dh-groups, checked 2026-09-25}
}

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