Lucent Technologies 6000 - Manual (Page 538)

15-2 MAX 6000/3000 Network Configuration Guide
Defining Static Filters
Filter overview
IP filters apply only to IP-related packets. They specify a forwarding action on the basis of
higher-level fields in IP packets (for example, the source or destination address, or the protocol
number). They operate on logical information, which is relatively easy to obtain.
Type of Service (TOS) filters set priority bits in the TOS header of IP packets. Other routers
can then use the information to prioritize and select links for particular data streams.
IPX filters apply only to NetWare packets. They specify a forwarding action on the basis of
higher-level fields, such as source or destination network, node, and socket numbers. Like IP
filters, IPX filters operate on logical information, which is relatively easy to obtain.
Data and call filters
Data filters are commonly used for security, but they can apply to any purpose that requires the
MAX unit to drop or forward specific packets. The focus is typically on keeping out traffic that
you do not want on a LAN. For example, you can use data filters to drop packets addressed to
particular hosts or to prevent broadcasts from going across the WAN. You can also use data
filters to allow users to access only specific devices across the WAN.
When you apply a data filter, its forwarding action (forward or drop) affects the actual data
stream by preventing certain packets from reaching the Ethernet from the WAN, or vice versa.
Data filters do not affect the idle timer, and a data filter applied to a Connection profile does
not affect the answering process.
Figure 15-1. Data filters drop or forward certain packets
Call filters prevent unnecessary connections and help the MAX unit distinguish active traffic
from noise. By default, any traffic to a remote site triggers a call, and any traffic across an
active connection resets the connection’s idle timer.
Figure 15-2. Call filters prevent certain packets from resetting the timer
When you apply a call filter, its forwarding action (forward or drop) does not affect which
packets are sent across an active connection. The forwarding action of a call filter determines
which packets can either initiate a connection or reset a session’s timer. When a session’s idle
WAN
Data filter
WAN
Call filter