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Appendix - G
SENS
 Wind River Systems, Inc. 1997
SENS
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G-2
“Scalable Enhanced Network Stack”
Modular driver/stack interface
 Enhanced Network Driver (END) supports polled network
drivers and multicasting.
 New layer (MUX) provides a protocol-independent interface
to the network driver.
Upgrade to 4.4 BSD codebase
Many scalability options
Contemporary Internet Features
Contd...
G-3
Scalability
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Include/exclude protocols individually (TCP, UDP, ICMP,
IGMP)
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Flexible configuration control of network stack default behavior
(see netLib.h)
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Tight control of network memory buffer pool configuration(see
netBufLib and usrNetwork.c)
G-4
Contemporary Internet Features
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Dynamic Host Configuration Protocol (DHCP)
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Routing Information Protocol (RIP)
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Open Shortest Path First (OSPF) available as an optional
component
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IP Multicasting
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Resolver (client) for DNS (Domain Name Service)
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Simple Network Time Protocol (SNTP)
G-5
DHCP
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G-6
Extends features provided by BOOTP
 Manual configuration for backward compatibility with
BOOTP
 Automatic configuration to assign a dynamically allocated
IP address
 Assignment may be temporary: Address “leased” to a client
for a limited time.
SENS supports DHCP client, server and relay agent operation
Routing
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Manual routing configuration with calls in routeLib to support
specification of subnet mask for a destination
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RIP (Routing Information Protocol) client and server support
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OSPF (Open Shortest Path First) support available at extra cost
G-7
IP Multicasting
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Allows more efficient transmission of data to multiple
destinations than broadcasting.
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Uses class D network addresses 224.0.0.0 through
239.255.255.255
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Consumers join a “multicast group.” All other hosts will be
unaffected by the transmission.
G-8
DNS Resolver
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DNS (Domain Name Service) is a system which provides
automatic conversion between host names and IP addresses. See
hostAdd() for manual mapping of names to IP addresses.
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Define INCLUDE_DNS_RESOLVER in config.h
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Set the macros RESOLVER_DOMAIN_SERVER and
RESOLVER_DOMAIN appropriately
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Resolver operation is fully integrated. (hostGetByName() and
hostGetByAddr() have been updated to use the resolver. Other
library routines, for example ping() and rcmd(), use these.)
G-9
SNTP Client & Server
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Simple Network Time Protocol
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Define INCLUDE_SNTPC for client support and
INCLUDE_SNTPS for server support in config.h
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sntpcTimeGet() is the basic client call
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Server requires a user provided function of the form
STATUS sntpsTimeHook (int request, void *pNtpTime)
Other library routines will set the request parameter to
SNTPS_TIME to retrieve the current 64-bit NTP
timestamp. See documentation for sntpsClockSet().
G-10