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`udp_max_buf`

Description	Controls how large send and receive buffers (in bytes) can be for a UDP socket.
Default	262,144 bytes
Range	65,536 to 1,073,741,824
Dynamic?	Yes
When to Change	Do not change the value. If this parameter is set to a very large value, UDP socket applications can consume too much memory.
Commitment Level	Unstable

IPQoS

This section describes an IPQoS tunable parameter.

`ip_policy_mask`

Description

Enables or disables IPQoS processing in any of the following callout positions: forward outbound, forward inbound, local outbound, and local inbound. This parameter is a bitmask as follows:

Not Used	Not Used	Not Used	Not Used	Forward Outbound	Forward Inbound	Local Outbound	Local Inbound
X	X	X	X	0	0	0	0

A 1 in any of the position masks or disables IPQoS processing in that particular callout position. For example, a value of 0x01 disables IPQoS processing for all the local inbound packets.

Default

The default value is 0, meaning that IPQoS processing is enabled in all the callout positions.

Range

0 (0x00) to 15 (0x0F). A value of 15 indicates that IPQoS processing is disabled in all the callout positions.

Dynamic?

Yes

When to Change

Change this parameter if you want to enable or disable IPQoS processing in any of the callout positions.

Commitment Level

Unstable

Per-Route Metrics

Starting in the Solaris 8 release, you can use the per-route metrics to associate some properties with IPv4 and IPv6 routing table entries.

For example, a system has two different network interfaces, fast ethernet interface and gigabit ethernet interface. The system default tcp_recv_hiwat is 24,576 bytes. This default is sufficient for the fast ethernet interface, but may not be sufficient for the gigabit ethernet interface.

Instead of increasing the system's default tcp_recv_hiwat, you can associate a different default TCP receive window size to the gigabit ethernet interface routing entry. By making this association, all TCP connections going through the route will have the increased receive window size.

Assuming IPv4, the following is in the routing table (netstat -rn).

192.123.123.0        192.123.123.4         U        1      4  hme0
192.123.124.0        192.123.124.4         U        1      4  ge0
default              192.123.123.1         UG       1      8

Do the following:

# route change -net 192.123.124.0 -recvpipe x

This means all connections going to the 192.123.124.0 network, which is on the ge0 link, use the receive buffer size x, instead of the default 24567 receive window size.

If the destination is in the a.b.c.d network, and there is no specific routing entry for that network, you can add a prefix route to that network and change the metric. For example:

# route add -net a.b.c.d 192.123.123.1 -netmask w.x.y.z
# route change -net a.b.c.d -recvpipe y

Note that the prefix route's gateway is the default router. Then all connections going to that network use receive buffer size y. If you have more than one interface, use the -ifp argument to specify which interface to use. This way, you can control which interface to use for specific destinations. To verify the metric, use the route(1M) get command.

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