Other LPAR routing rule configuration

Most typical Linux® installations create default routing behavior for the LPAR that will likely utilize an OSA interface as the default route. This means that some additional routing configuration is needed to specify that specific IP traffic should use the HiperSockets™ link. In the configuration on the 2nd LPAR, the IP traffic destined for the KVM guest was directed to use the HiperSockets interface. In IP address terms, the IP traffic (for the KVM guest) using subnet 10.131.211.x was routed across the HiperSockets link to IP address 172.31.56.1.

To accomplish this routing manually, the following command was used:

[root@otherlpar ~]# route add -net 10.131.211.0/24 gw 172.31.56.1 [device hs56k_0]

For the KVM on Z Linux installation, to configure this routing rule into a static route, the file /etc/sysconfig/network-scripts/route-hs56k_0 was created with the following contents:

# --- IPv4 routes in CIDR prefix notation: 
# TargetSubnet/netmask     [Gateway]          Interface 
# 
10.131.211.0/24            via 172.31.56.1    dev hs56k_0

The added routing rules for both the KVM guest and the other LPAR specify a target subnet, a target device and gateway IP address. The gateway typically marks the boundary from one network to another. The gateway provides the transition in the TCP/IP routing used to cross from one subnet target to another. The gateway then uses its routing rules to forward the IP traffic to the target subnet. The gateway addresses in both static routes are necessary to enable the IP traffic to flow across the desired subnets.