Installation guide

DHCP

Dynamic Host Conﬁguration Protocol (DHCP) enables a host to get an Internet

protocol (IP) address and other system conﬁguration parameters preconﬁgured by

the administrator on the DHCP sever. DHCP also enables the host to give up this

address when it is no longer required, or when the designated period for its use

ends. This protocol improves on the traditional IP address allocation where the

system administrator must assign or change each IP address individually. Both

DHCP server and client-side support are provided.

For more information, see TCP/IP Network Administration Guide.

NFS Client Failover

Client failover provides for a high level of availability of read-only ﬁle systems by

allowing the client to mount ﬁles from another server as needed. The failover is

transparent to the client, so work is not disturbed if one server has problems as long

as there is a replica available.

More information about NFS client failover can be found in NFS Administration

Guide.

Variable Length Subnet Mask (VLSM)

Previously, the Solaris operating environment supported the use of a single netmask

for each network number in use on a network. The netmask determines which bits of

an IP network number represent the subnet, and which represent the host number.

Using variable-length subnet masks (VLSM) enables more efﬁcient use of IP

addresses in large networks. With VLSM, the TCP/IP administrator can now use

multiple netmasks for a given network number, tailoring each mask according to the

size of each individual subnetwork. When deciding how to route an IP packet,

Solaris automatically uses the longest matching netmask.

For example, in prior releases an administrator could subdivide the network

192.168.1.0 into eight subnets by using a netmask of 255.255.255.224. By using VLSM,

this network number can instead be broken into

Two subnets with a netmask of 255.255.255.192, and

Four subnets with a netmask of 255.255.255.224

In addition, the use of VLSM allows supernetting or aggregation of network

numbers, which can result in substantial savings in the sizes of routing tables carried

by network routers. These two techniques make it possible to implement Classless

Inter-Domain Routing (CIDR) as described in RFC1519.

To fully utilize VLSM in a network, CIDR-aware protocols such as OSPF, BGP-4, or

RIPv2 must be used.

What’s New: A Closer Look 3-29