The procedure to upgrade a Redundancy Group containing two I-SBCs in a 1:1 HA formation is essentially the same as the process to upgrade up to five M-SBC instances in an N:1 Redundancy Group, except that you only need to upgrade two nodes. To upgrade an I-SBC 1:1 HA deployment, refer to the procedure Upgrading M-SBCs in an N:1 Redundancy Group and complete the steps to upgrade the first two nodes, beginning with the standby I-SBC.