OSA-Integrated Console Controller OSA-ICC Enhancements Checksum offload for in QDIO mode (CHPID type OSD) The supported operating systems are listed in Table 7-8 on page 267 and Table 7-9 on  page 269. The OSA-Express 1000BASE-T Ethernet features provide the Integrated Console Controller  (OSA-ICC) function, which supports TN3270E (RFC 2355) and non-SNA DFT 3270  emulation. The OSA-ICC function is defined as CHPID type OSC and console controller, and  includes multiple LPAR support as shared or spanned channels. With the OSA-ICC function, 3270 emulation for console session connections is integrated in  the z15 through a port on the OSA-Express7S 1000BASE-T, OSA-Express7S GbE,  OSA-Express6S 1000BASE-T, or OSA-Express5S 1000BASE-T. OSA-ICC can be configured on a PCHID-by-PCHID basis, and is supported at any of the  feature settings. Each port can support up to 120 console session connections. To improve security of console operations and to provide a secure, validated connectivity,  OSA-ICC supports Transport Layer Security/Secure Sockets Layer (TLS/SSL) with Certificate  Authentication staring with z13 GA2 (Driver level 27). Note:  OSA-ICC supports up to 48  secure  sessions per CHPID (the overall maximum of  120 connections is unchanged). With HMC 2.14.1 and newer the following enhancements are available: The supported operating systems are listed in Table 7-8 on page 267 and Table 7-9 on  page 269. Checksum offload provides the capability of calculating the Transmission Control Protocol  (TCP), User Datagram Protocol (UDP), and IP header checksum. Checksum verifies the  accuracy of files. By moving the checksum calculations to a Gigabit or 1000BASE-T Ethernet  feature, host processor cycles are reduced and performance is improved. 310  IBM z15 (8561) Technical Guide GLYPH<SM590000> The IPv6 communications protocol is supported by OSA-ICC 3270 so that clients can  comply with regulations that require all computer purchases to support IPv6. GLYPH<SM590000> TLS negotiation levels (the supported TLS protocol levels) for the OSA-ICC 3270 client  connection can now be specified: – TLS 1.0 OSA-ICC 3270 server permits TLS 1.0, TLS 1.1, and TLS 1.2 client  connections. – TLS 1.1 OSA-ICC 3270 server permits TLS 1.1 and TLS 1.2 client connections. – TLS 1.2 OSA-ICC 3270 server permits only TLS 1.2 client connections. GLYPH<SM590000> Separate and unique OSA-ICC 3270 certificates are supported (for each PCHID), for the  benefit of customers who host workloads across multiple business units or data centers,  where cross-site coordination is required. Customers can avoid interruption of all the TLS  connections at the same time when having to renew expired certificates. OSA-ICC continues to also support a single certificate for all OSA-ICC PCHIDs in the  system.