Cluster I/O Protocols (CIP) Configuration and Management Manual (H06.16+, J06.05+)

Conversion of Limited Broadcast to Subnet-Directed Broadcast
If the destination address is the limited broadcast address (255.255.255.255), conventional
TCP/IP and NonStop TCP/IPv6 convert the address to a subnet-directed broadcast address (the
specific subnetid and hostid are all ones) whether the socket is bound or unbound. CIP does this
conversion only if the socket is unbound.
Binding to a Recently Used Address and Port
Conventional TCP/IP and NonStop TCP/IPv6 allowed immediate reuse of an address and port if
the SO_REUSEADDR socket option is set on the next use. CIP requires that the SO_REUSEADDR
option be set on both the previous and next use. If the SO_REUSEADDR option is not set on both
the previous and next use, there can be a delay of up to several minutes the address and port can
be reused.
Round-Robin Socket Support Considerations
The NonStop TCP/IPv6 and Parallel Library TCP/IP round-robin filtering feature introduced
considerations for applications and some of these considerations also apply to CIP:
• If the first application that binds to a TCP or UDP port using round-robin filtering is a privileged
user (for example, a super-group user), all further applications sharing the port must also be
privileged.
• All applications must bind using the same family value (for example, AF_INET or AF_INET6).
• If your application uses round robin sockets where the same a TCP or UDP port is shared
between an IPv4 socket and an IPv6 socket, you must change the application to use different
TCP or UDPs for the different address families. Mixed family sockets cannot share the same
TCP or UDP.
Socket IOCTL Differences
This section documents the changes to IOCTL commands that can be issued from the Guardian
library calls socket_ioctl and socket_ioctl_nw and the Open System Services (OSS) system call
ioctl.
Adding and Deleting Routes by Name
SIOCADDRT (add route) and SIOCDELRT (delete route) behave differently in CIP.
Conventional TCP/IP and NonStop TCP/IPv6 can use route names to identify routes as well as
addresses. CIP does not have route names. CIP can add routes, but does not save or assign a
route name, so route names cannot be used to identify a route for deleting. If a route name is used
with SIOCDELRT, the request is ignored if the compatibility error DEFINE is SUPPRESS or else
returns an error.
Deleting ARP Entries
SIOCDARP (delete ARP entry) behaves differently.
When an ARP table entry is deleted using an IOCTL command in conventional TCP/IP or NonStop
TCP/IPv6, the entry is completely removed. CIP retains the entry, but shows its HW address field
as incomplete.
Getting Netmask and Broadcast Address on IPv6 Sockets
SIOCGIFBRDADDR (get broadcast address) and SIOCGIFNETMASK (get network address mask)
are supported differently in CIP, for IPv6 sockets.
NonStop TCP/IPv6 allows these IOCTL commands on IPv4 and IPv6 sockets, but on IPv6 sockets,
NonStop TCP/IPv6 returns IPv4 addresses. CIP does not support the operation on IPv6 sockets at
all.
190 IP CIP Migration, Compatibility and Operational Differences