subnetconfig(1M)

NAME

subnetconfig − configure subnet behavior

SYOPNSIS

subnetconfig local
subnetconfig remote
subnetconfig

DESCRIPTION

subnetconfig is used to set the value of an internal flag which in turn controls subnet behavior on a given host. Subnetting is an addressing scheme for partitioning hosts in a particular network into different sub-networks. Depending on the setting of the internal flag, each subnet in a network is viewed as being a distinct network or as belonging to the same network when choosing maximum size of outbound TCP packets. The flag also affects some of the error codes returned when trying to reach unreachable hosts. subnetconfig has no effect on routing decisions.

TCP selects a maximum outbound packet size at connection setup time. When connecting to hosts in the same network, the maximum packet size is limited only by the MTU size of the interface on which packets will be sent. For connections to destinations not in the same network, TCP limits segments to 512 bytes. By default, all subnets of the same network are treated as being part of the same network.

Command Forms

The subnetconfig command can be used in any of the following three forms:

subnetconfig local (default behavior)
Set the internal flag so that all destinations in the same network (destination network number equals host network number), including all subnets defined in the network, are treated as being in the local network when choosing TCP segment sizes. Outbound TCP packet size for destinations in the local network is determined by the capacity of the interface on which packets are sent for that connection. TCP packets sent to a destinations in a different network are limited to 512 bytes.

Returns error code EHOSTUNREACHABLE if attempt is made to send packets to an unreachable host in the same network.

subnetconfig remote
Set the internal flag so that all destinations in the same network (destinations network number equals host network number), that are not part of the directly attached subnet (destination subnet number not equal to host subnet number) are treated as being in a distinct network. TCP then selects a maximum packet size of 512 bytes for all connections to destinations that are not part of the directly attached subnet. The size of packets sent to the directly attached subnet remains unchanged (governed by the MTU of the interface).

Returns error code ENETUNREACHABLE if attempt is made to send packets to an unreachable host on a different subnet of the same network. When trying to send a packet to an unreachable host in the same subnet, EHOSTUNREACHABLE is returned.

subnetconfig Display the current setting of the internal flag.

AUTHOR

subnetconfig was developed by HP.