## 11.8.3 IP Partnership and data compression 

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: 

## 11.8.4 VLAN support 

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 

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. 

