Sun Microsystems 3U User Manual

Page 71

Chapter 5

Editing SunATM Configuration Files

In most network configurations, the ATM address assigned to the local interface is

$myaddress

; using this variable in the l entry makes it possible to use identical

aarconfig

files on all Classical IP clients using a given server.

The

sunmacsel

N variables can be used in conjunction with a prefix, as well as with

known server addresses that are not bound to a particular system. As an example,
consider the case where a server that supports 50 clients fails. If the ATM address of
the server is specific to that particular server, you must change the s entry on all 50
clients to switch to a backup server. However, if the ATM address used for that
server is

$prefix:$sunmacsel3

, this address is not only guaranteed to be unique,

since it uses reserved medium access control (MAC) addresses. You can also simply
assign that address to the backup server on the same switch by changing the l entry
to an s entry on one system and bringing up a new server with no changes to the
clients.

Note –

The

sunmacsel

N variables do not include a prefix since a client and server

may be on different switches and thus have different local prefix values.

In the case of a single-switch network, you can use

localswitch_server

as a

well-known server address that includes the prefix associated with the local switch
and a MAC address. It will restrict server access to clients on the local switch and
provide a unique ATM address among all ATM clients connected to that switch.
Thus, any host with a network prefix other than that of the local switch will be
refused a connection to the ARP server if the ARP server's address is

$localswitch_server

A wild card matching one or two hexadecimal digits within
any colon-separated field. For example,

$prefix:$anymac:?

is equivalent to both

$prefix:$anymac:??

and

$prefix:$anymacsel

. However, it is not the same as

$prefix:$anymacsel:0?

, which requires that the first digit

of the selector byte is a

. This wild card should only be used in

a entries.

sunmacsel

The concatenation of one of a series of reserved MAC addresses
and

$sel

to create a block of reserved ATM ARP server

addresses. N should be a decimal number in the range 0–199.

localswitch_server

The concatenation of

$prefix

, a unique reserved MAC

address, and

$sel

. When used as a server address, restricts

server access to clients connected to the local switch only.

TABLE 5-4

Predefined SunATM Variables (Continued)

Variable

Description