User`s guide

XSR User’s Guide 141
Chapter 8 Implementing Dial Services
Configuring Dialer Services
Dialer Strings
Setting dialer strings is straightforward but their configuration is very
flexible. You can specify multiple dialer strings for the same dialer interface
and each dialer string can be associated with a different dialer map class.
Dialer Pool
Each dialer interface uses one group of physical interfaces called a dialer pool.
The physical interfaces in a dialer pool are called into use based on a priority
value for selection by the XSR. Again, Serial interfaces can belong to multiple
dialer pools, allowing a small number of resources to service a large number
of users. The disadvantage of this method is that all resources may be in use
when a user tries to access them.
Addressing Dialer Resources
There are two ways of setting up addressing on dialer resources, as follows.
 Applying a Subnet to the Dialer Cloud - Each site linked to the dialer
cloud receives a unique node address on a shared subnet for use on
its dialer interface. This method is similar to numbering a LAN or
multipoint WAN and simplifies the addressing scheme and creating
static routes.
 Using Unnumbered Interfaces - Similar to using unnumbered
addressing on leased line point-to-point interfaces, the address of
another interface on the XSR is borrowed for use on the dialer
interface. Unnumbered addressing takes advantage of the fact that
there are only two devices on the point-to-point link.
The routing table points to an interface (the dialer interface) and a next-hop
address. When building static routes for unnumbered interfaces the XSR must
be configured with the interface that finds the next-hop out.
Configuring Encapsulation
When a clear data link is established between two peers, traffic must be
encapsulated and framed for transport across the Dialer media.