Update, July 16 2025: This change will occur between July 28th and July 31st.
In the coming weeks Cisco will be changing the egress IPv6 ranges used by the Secure Access web proxy. Today there is a /64 subnet published for each data center (see https://docs.sse.cisco.com/sse-user-guide/docs/secure-access-nat-as-a-service#ipv6-shared-ranges).
As we prepare for enhancements to our IPv6 functionality we are consolidating the egress IPv6 range for web proxy into a single subnet: 2603:5004::/36
This consolidated range will be used for all internet-destined web and non-web traffic.
The majority of internet-destined traffic on Secure Access uses IPv4 and is not impacted by this change. In addition to this post, we are reaching out via email to customers with significant volumes of IPv6 traffic to ensure they are aware of the change.
