Overview

TCP

UDP

Raw IP

IP

Network

Alias table

DNS

Loopback

Route table

Overview

The TCP/IP software is installed with default parameters that are adequate for a simple host configuration, with one network interface and a moderate amount of network traffic. After you determine your host and network configuration, you should review the TCP/IP parameters listed in this chapter and reset them as needed.

The parameters are accessed via the INtime Configuration utility.

Start > Programs > INtime > INtime Configuration

1. Select "Real-time Network"
2. Select "NIC Configuration"
3. Select "Advanced"

Some values are not present in the default configuration, and may be added. The default value for each parameter is taken when the parameter is absent.

Note:   All numeric values in the following tables are hexadecimal. String values are enclosed in single quotes.

TCP [TCP]

Parameters

Key	Default Value	Description
DEFMSS	200	Default maximum segment size
DEFRTT	3	Default round trip time; not currently used
RCVSPACE	4000	Maximum receive space per socket
SNDSPACE	4000	Maximum send space per socket
SBEFFICIENCY	8	Socket buffer efficiency factor; not currently used
KEEPINIT	4B	Connection establishment time out
KEEPIDLE	1C20	Maximum connection idle time before probing
KEEPINTVL	4B	Connection probe interval
ALWAYSKEEPALIVE	0	Probe all idle connections
CTLBUFS	40	Maximum total control buffers
TRANSBUFS	40	Maximum total transaction buffers
MAXTRANS	10	Maximum simultaneous IP transactions
MAXPORTS	0	Maximum port ids
LOWFIXPID	1	Well-known port id range
HIFIXPID	3FF
LOWAUTOPID	400	Ephemeral port id range
HIAUTOPID	1387
RCVPRI	80	Receive thread priority
LSTNPRI	80	Listen thread priority
TIMPRI	80	Timer thread priority
RCVSTK	2000	Receive thread stack size
LSTNSTK	2000	Listen thread stack size
TIMSTK	2000	Timer thread stack size
ACKDELAY	14	ACK delay timeout (x 10ms)
MINREXMIT	100	min 2, max 100 in 10ms units. Adjust the retransmit timer calculation for TCP.
DEBUGLEVEL	0	Debug level (set to non-zero for debug output)

Description

DEFMSS	Default maximum size of segments sent by the TCP job. To avoid fragmentation at the IP level, set this parameter to the smallest maximum packet size that a sent packet is likely to encounter in its route to the destination. Once a connection is established, the source and destination TCPs negotiate an optimum maximum packet size.
RCVSPACE	Size, in bytes, of the receive buffer area per TCP socket. The receive buffer holds incoming data until it is received at the socket by the application.
SNDSPACE	Size, in bytes, of the send buffer area per TCP socket. The send buffer holds outgoing data until it is successfully sent to the destination.
KEEPINIT	Connection establishment timeout, in seconds.
KEEPIDLE	Maximum connection idle time, in seconds. After this time, TCP begins sending keepalive probes to the remote host.
KEEPINTVL	The time interval between probes to an idle remote host. Up to 9 probes are sent before dropping the connection.
ALWAYSKEEPALIVE	Zero indicates that only sockets that have the SO_KEEPALIVE option set should send keepalive probes to idle remote hosts. Non-zero indicates that all sockets should send probes on idle connections.
ACKDELAY	Time to delay before sending an ACK for data received, in 10 millisecond units. Delaying the ACK can allow subsequent data sent to be combined with the ACK packet, for efficiency.
CTLBUFS	Maximum number of control buffers allocated for the TCP job. Control buffers are used by the TCP job whenever data is sent or received through a TCP socket. If insufficient control buffers are available, an ENOBUFS error is returned to the application. This indicates that the number of configured control buffers for the TCP job should be increased. The default value should be used for most applications.
TRANSBUFS	Maximum number of transaction buffers allocated for the TCP job. Transaction buffers are used by the TCP job whenever data is sent or received through a TCP socket. If insufficient transaction buffers are available, an ENOBUFS error is returned to the application. This indicates that the number of transaction buffers for the TCP job should be increased. The default value should be used for most applications.
MAXTRANS	Maximum number of simultaneous transactions allowed between the TCP job and the IP job. Transactions are used by the TCP job whenever data is sent or received through a TCP socket. If insufficient transactions are available, an ENOBUFS error is returned to the application. This indicates that the number of transactions for communication between the TCP job and the IP job should be increased. The default value should be used for most applications.
MAXPORTS	Maximum number of port ids available to the TCP job. Whenever a TCP socket is bound (see the bind() system call), a local port id is assigned to the socket. This parameter specifies the maximum number of unique port ids available.
LOWFIXPID, HIFIXPID	When a TCP socket is bound (see the bind() system call), the user may specify the local port id that is to be associated with the socket. Define the range of port id values that may be specified. Must be within the range of 0 to MAXPORTS, exclusive, and must not overlap the port id range defined by LOWAUTOPID and HIAUTOPID.
LOWAUTOPID, HIAUTOPID	When a TCP socket is bound (see the bind() system call), the user may request that the TCP job select the local port id that is to be associated with the socket (known as an ephemeral port id). Define the range of port id values that the TCP job may choose from. Must be within the range of 0 to MAXPORTS, exclusive, and must not overlap the port id range defined by LOWFIXPID and HIFIXPID.

UDP [UDP]

Parameters

Key	Default Value	Description
CHECKSUM	1	Enable checksum
RCVSPACE	0A000	Maximum receive space per socket
CTLBUFS	40	Maximum total control buffers
TRANSBUFS	40	Maximum total transaction buffers
MAXTRANS	10	Maximum simultaneous IP transactions
MAXPORTS	0	Maximum port ids
LOWFIXPID	1	Well-known port id range
HIFIXPID	3FF
LOWAUTOPID	400	Ephemeral port id range
HIAUTOPID	1387
RCVPRI	80	Receive thread priority
RCVSTK	2000	Receive thread stack size
DEBUGLEVEL	0	Debug level

Description

CHECKSUM	A value of 0 disables checksum calculation on all segments sent or received by the UDP job. A value of 1 enables checksum calculation. This parameter should normally be set to 1.
RCVSPACE	Size of the receive buffer area per UDP socket, in bytes. The receive buffer holds incoming data until it is received at the socket by the application.
CTLBUFS	Maximum number of control buffers allocated for the UDP job. Control buffers are used by the UDP job whenever data is sent or received through a UDP socket. If insufficient control buffers are available, an ENOBUFS error is returned to the application. This indicates that the number of configured control buffers for the UDP job should be increased. The default value should be used for most applications.
TRANSBUFS	Maximum number of transaction buffers allocated for the UDP job. Transaction buffers are used by the UDP job whenever data is sent or received through a UDP socket. If insufficient transaction buffers are available, an EBOBUFS error is returned to the application. This indicates that the number of transaction buffers for the UDP job should be increased. The default value should be used for most applications.
MAXTRANS	Maximum number of simultaneous transactions allowed between the UDP job and the IP job. Transactions are used by the UDP job whenever data is sent or received through a UDP socket. If insufficient transactions are available, an ENOBUFS error is returned to the application. This indicates that the number of transactions for communication between the UDP job and the IP job should be increased. The default value should be used for most applications.
MAXPORTS	Maximum number of port ids available to the UDP job. Whenever a UDP socket is bound (see the bind() system call), a local port id is assigned to the socket. This parameter specifies the maximum number of unique port ids available.
LOWFIXPID, HIFIXPID	When a UDP socket is bound (see the bind() system call), the user may specify the local port id that is to be associated with the socket. Define the range of port id values that may be specified Must be within the range of 0 to MAXPORTS, exclusive, and must not overlap the port id range defined by LOWAUTOPID and HIAUTOPID.
LOWAUTOPID, HIAUTOPID	When a UDP socket is bound (see the bind() system call), the user may request that the UDP job select the local port id that is to be associated with the socket (known as an ephemeral port id). Define the range of port id values that the UDP job may choose from. Must be within the range of 0 to MAXPORTS, exclusive, and must not overlap the port id range defined by LOWFIXPID and HIFIXPID.

Raw IP [RIP]

Parameters

Key	Default Value	Description
CTLBUFS	20	Maximum total control buffers
TRANSBUFS	20	Maximum total transaction buffers
MAXTRANS	8	Maximum simultaneous IP transactions
MAXPORTS	80	Maximum port ids
RCVPRI	80	Receive thread priority
RCVSTK	2000	Receive thread stack size
DEBUGLEVEL	0	Debug level

Description

CTLBUFS	Maximum number of control buffers allocated for the Raw IP job. Control buffers are used by the Raw IP job whenever data is sent or received through a Raw IP socket. If insufficient control buffers are available, an ENOBUFS error is returned to the application. This indicates that the number of configured control buffers for the Raw IP job should be increased. The default value should be used for most applications.
TRANSBUFS	Maximum number of transaction buffers allocated for the Raw IP job. Transaction buffers are used by the Raw IP job whenever data is sent or received through a RAW IP socket. If insufficient transaction buffers are available, an ENOBUFS error is returned to the application. This indicates that the number of transaction buffers for the Raw IP job should be increased. The default value should be used for most applications.
MAXTRANS	Maximum number of simultaneous transactions allowed between the Raw IP job and the IP job. Transactions are used by the Raw IP job whenever data is sent or received through a Raw IP socket. If insufficient transactions are available, an ENOBUFS error is returned to the application. This indicates that the number of transactions for communication between the Raw IP job and the IP job should be increased. The default value should be used for most applications.
MAXPORTS	Maximum total number of Raw IP sockets that may be created.

IP [IP]

Parameters

Key	Default Value	Description
IFNAMES	"ETH0, LO0, SL0"	Interface names
BUFHEAPSIZE	200	Total receive buffer size in Kbytes
FORWARDING	0	Enable IP forwarding
LOCALSUBNETS	1	Enable local subnets
TTL	8	Default segment time to live
TOS	0	Default type of service
ARPTIMEOUT	20	ARP cache flush timeout in minutes
ARPTOEXTEND	0 (FALSE)	Extend timeout period if packet received from host
ARPRCVGRTS	0 (FALSE)	Process received gratuitous packets
ARPSNDGRTS	0 (FALSE)	Send gratuitous packet on start
CTLBUFS	80	Maximum total control buffers
TRANSBUFS	80	Maximum total transaction buffers
RCVPRI	80	Receive thread priority
RCVSTK	2000	Receive thread stack size
DEBUGLEVEL	0	Debug level

Description

FNAMES	A list of interfaces that the IP job may communicate with to send and receive datagrams. Each interface name in the list must match an interface description included in the :config:tcp.ini file (e.g., [ETH0] ), and also must match the name associated with a NIC driver loaded in the :config:tcpstart submit file.
BUFHEAPSIZE	Total buffer space, in Kbytes, available to the IP job for sending and receiving datagrams. The buffers specified in the interface descriptions (e.g., the RCVBUFS parameter of the [ETH0] interface description) are allocated from the buffer space defined here.
FORWARDING	If this host is to forward packets from one network segment to another, set this parameter to 1. If not, set it to 0.
LOCALSUBNETS	If this host is directly connected to a network that is divided into subnets, set this parameter to 1. If not, set it to 0.
TTL	Default time to live for outgoing datagrams. The TTL is used to limit the life of TCP segments and prevent packets from endlessly circling the Internet on the way to some unreachable destination.
TOS	Default type of service for outgoing datagrams. This parameter encodes both precedence and the type of service as defined by the MIL-STD 1777. The upper three bits of the byte encode the precedence; the lower five bits encode the type of service.
ARPTIMEOUT	The number of minutes after which a complete ARP table entry will be deleted from the ARP cache if no ARP packets from the associated host are observed on the network.
CTLBUFS	Maximum number of control buffers allocated for the IP job. Control buffers are used by the IP job whenever data is sent or received. If insufficient control buffers are available, an ENOBUFS error is returned to the application. This indicates that the number of configured control buffers for the IP job should be increased. The default value should be used for most applications.
TRANSBUFS	Maximum number of transaction buffers allocated for the IP job. Transaction buffers are used by the IP job whenever data is sent or received. If insufficient transaction buffers are available, an ENOBUFS error is returned to the application. This indicates that the number of transaction buffers for the IP job should be increased. The default value should be used for most applications.

Network [ETH0]

Ethernet parameters

Key	Default Value	Description
HOST	'206.103.53.115'	Interface IP address
NETMASK	'255.255.255.0'	Net mask
DEFROUTE	'206.103.53.250'	Default route
RCVBUFS	3F	Maximum receive buffers
MAXTRANS	6F	Maximum simultaneous transactions
ALIASNAMES	'ALIAS0'	List of alias entries

Network interface parameters description

HOST	The IP address associated with this interface.
NETMASK	The net mask for the IP address associated with this interface.
DEFROUTE	The default route. If the destination of a datagram is not on the network attached to this interface, the default route is used as a destination. The host at the default route address will then forward the datagram to the desired destination. Only one interface should configure a default route.
RCVBUFS	The number of buffers allocated to receive datagrams from this interface. These buffers are allocated from the memory pool defined by the IP job's BUFHEAPSIZE configuration parameter. Set this parameter to the maximum number of datagrams expected to be received at one time on this interface.
MAXTRANS	The maximum number of simultaneous transactions between the IP job and this interface. Each datagram sent or received consumes one transaction. The transaction is recycled when the send or receive is processed. Set this parameter to the sum of the maximum number of incoming datagrams expected at one time (i.e., the value of the RCVBUFS parameter, above) plus the maximum expected number of simultaneous sends to this interface.
ALIASNAMES	A list of aliases for the interface. Alias names allow alternate IP addresses, netmasks and broadcast addresses to be associated with an interface. Each alias name in the list must match an AliasName included in the :config:tcp.ini file (e.g., [ALIAS0] ). For details about AliasName, continue to Alias table in the next section.

Alias table [AliasName]

Table entry

Key	Default Value	Description
HOST	'192.168.2.17'	Alias IP address
MASK	'255.255.255.0'	Net/subnet mask
BCAST	'192.168.2.255'	Alias broadcast address

Name parameter description

HOST	The alias IP address associated with this interface.
NETMASK	The net mask for the alias IP address associated with this interface.
BCAST	The alias broadcast address associated with this interface. This parameter is optional. If it is omitted, a default broadcast address will be formed from the alias IP address and netmask.

DNS [DNS]

DOMAIN	A string containing the name of the local domain.
SERVER1	A string that contains the IP address of the primary DNS server used by the client
SERVER2, SERVER3	Each of these parameters takes a string containing the IP addresses of secondary DNS servers. A total of three servers may be configured. If this section is not defined, or no servers are defined, then DNS name resolution does not occur.

Loopback [LO0]

Parameters

Key	Default Value	Description
HOST	'127.0.0.1'	Interface IP address
NETMASK	'255.255.0.0'	Net mask
RCVBUFS	3F	Maximum receive buffers
MAXTRANS	6F	Maximum simultaneous transactions

Pseudo-driver interface parameters description

HOST	The IP address associated with the loopback interface.
NETMASK	The net mask for the IP address associated with the loopback interface.
RCVBUFS	The number of buffers allocated to receive datagrams from this interface. These buffers are allocated from the memory pool defined by the IP job's BUFHEAPSIZE configuration parameter. Set this parameter to the maximum number of datagrams expected to be received at one time on this interface.
MAXTRANS	The maximum number of simultaneous transactions between the IP job and this interface. Each datagram sent or received consumes one transaction. The transaction is recycled when the send or receive is processed. Set this parameter to the sum of the maximum number of incoming datagrams expected at one time (i.e., the value of the RCVBUFS parameter, above) plus the maximum expected number of simultaneous sends to this interface.

Route table [ROUTEn]

Note: n is a number from 0 (zero) to 15.

Table entry

Key	Default Value	Description
DEST	'206.163.82.4'	Destination IP address
MASK	'255.255.255.0'	Net/subnet mask
GATEWAY	'172.16.1.250'	Gateway IP address
FLAGS	'GH'	Gateway/Host Flags

Parameter description

DEST	The IP address of the route destination. This may be a host address or a network address.
MASK	The net mask for the IP address associated with the destination.
GATEWAY	If the route is through a gateway, this parameter specifies the IP address of the gateway host. This parameter is not needed for routes to destinations that are directly connected to the sending host.
FLAGS	The "H" flag indicates that the route is to a host. The absence of the "H" flag indicates that the route is to a network. The "G" flag indicates that the route is through a host, whose IP address is specified by the GATEWAY parameter that acts as a gateway to the destination. The absence of the "G" flag indicates that the route is direct to the destination. A GATEWAY parameter is not needed for a direct route.

See Also

TCP/IP system calls