11.8.3 IP Partnership and data compression 11.8.4 VLAN support When creating an IP partnership between two systems, you can specify whether you want to  use the data compression. When enabled, IP partnership compression compresses the data  that is sent from a local system to the remote system and potentially uses less bandwidth  than with uncompressed data. It is also used to decompress data that is received by a local  system from a remote system. Data compression is supported for IPv4 or IPv6 partnerships. To enable data compression,  both systems in an IP partnership must be running a software level that supports IP  partnership compression (V7.7 or later). To fully enable compression in an IP partnership, each system must enable compression.  When compression is enabled on the local system, data sent to the remote system is  compressed so it needs to be decompressed on the remote system, and vice versa. Although IP compression uses the same RtC algorithm as for volumes, a RtC license is not  needed on any of the local or remote system. Replicated volumes by using IP partnership compression can be compressed or  uncompressed on the system because no link exists between volumes compression and IP  Replication compression. Consider the following points:  Starting with V7.4, VLAN tagging is supported for iSCSI host attachment and IP replication.  Hosts and remote-copy operations can connect to the system through Ethernet ports. Each  traffic type has different bandwidth requirements, which can interfere with each other if they  share IP connections. VLAN tagging creates two separate connections on the same IP  network for different types of traffic. The system supports VLAN configuration on both IPv4  and IPv6 connections. When the VLAN ID is configured for IP addresses that is used for iSCSI host attach or  IP replication, the VLAN settings on the Ethernet network and servers must be configured  correctly to avoid connectivity issues. After the VLANs are configured, changes to the VLAN  settings disrupt iSCSI and IP replication traffic to and from the partnerships. During the VLAN configuration for each IP address, the VLAN settings for the local and  failover ports on two nodes of an I/O Group can differ. To avoid any service disruption,  switches must be configured so that the failover VLANs are configured on the local switch  ports and the failover of IP addresses from a failing node to a surviving node succeeds. If  failover VLANs are not configured on the local switch ports, no paths are available to the IBM  Spectrum Virtualize system nodes during a node failure and the replication fails. Consider the following requirements and procedures when implementing VLAN tagging: GLYPH<SM590000> VLAN tagging is supported for IP partnership traffic between two systems. GLYPH<SM590000> VLAN provides network traffic separation at the layer 2 level for Ethernet transport. GLYPH<SM590000> Read operation decompresses the data GLYPH<SM590000> Decompressed data is transferred to the Remote Copy code GLYPH<SM590000> Data is compressed before being sent over the IP link GLYPH<SM590000> Remote system remote copy code decompresses the received data GLYPH<SM590000> Write operation on a volume compresses the data Chapter 11. Advanced Copy Services  579