Installation guide

and provides instructions for converting the ﬁles to the new format. The

document and conversion utility, README-DB237 and conv185-237,

respectively, are located in the /etc/join directory.

4.4.12 TCP Timestamp and Selective Acknowledgement Support

Tru64 UNIX Version 4.0F includes support for the TCP Selective

Acknowledgment Options (SACK) as well as the TCP Timestamp and

PAWS (Protect Against Wrapped Sequence Numbers) options. These TCP

options can help improve TCP performance over unreliable networks. RFC

2018 TCP Selective Acknowledgment Options describes the SACK options.

RFC 1323 TCP Extensions for High Performance describes both the

Timestamp and PAWS option.

4.4.13 Latent Support for Multiple Network Adapters in a Subnet

Tru64 UNIX Version 4.0F provides latent support for a single system to have

multiple network adapters in the same subnet; for example, tu0 conﬁgured

with IP address 192.24.156.20 and tu1 conﬁgured with IP address

192.24.156.21, both with the same netmask. Previous versions require each

network adapter to be in a separate physical subnet.

On connection establishment, the kernel chooses the interface that has the

fewest number of connections. This connection-balancing effect could lead

to greater throughput than on a system with just one network adapter per

subnet.

You should use this feature only if both of the following conﬁguration

situations are true:

• The underlying network topology is switched, and it is of type Ethernet

or FDDI.

• You are not running a routing daemon.

The feature might affect the operation of network software or, for example:

• Multicast transmission might not work properly.

• Utilities such as traceroute might give varied output, since the

interface used might change from packet to packet.

To enable this feature, you must use dbx on the kernel and set the

routemode variable to 1. You must patch the kernel for this to persist

Base System Software Notes 4–33