gtpc1m21 | Transmission Control Protocol/Internet Protocol |
Typically, a gateway is a router that connects networks. With an OSA-Express connection, the default gateway to be used as the first hop of a route for outbound packets is defined or modified by entering the ZOSAE command with the DEFINE or MODIFY parameter specified. A maximum of two default gateways for each OSA-Express connection can be defined, which prevents the network from having a single point of failure. You can define other gateways (besides the default gateway) by setting up IP routing table entries. See Defining Gateways for more information.
If you want to use VIPAs, gateways that are on the network to which the OSA-Express card connects must support Routing Information Protocol (RIP) Version 2 on the interfaces connected to that network. RIP informs the IP routers of the path to take to reach a specific TPF VIPA. The connections to other networks can use routing protocols other than RIP. The TPF system only uses RIP to broadcast VIPA information to the gateways.
All hosts and routers in a network can use RIP to share routing information. RIP uses User Datagram Protocol (UDP) well-known port 520. RIP messages are sent using the multicast protocol, which is a protocol that allows a single packet to be sent to all hosts and routers on the network that may need to receive the packet. However, responses to RIP requests are sent only to the node that sent the request. The TPF system sends out RIP messages to inform the network about path activations and failures. The TPF system is an IP host and not an IP router; therefore, the TPF system does not maintain routing tables or save RIP information that is received from the gateways.