Avaya Configuring Traffic Filters and Protocol Prioritization Manual do Utilizador descarregar pdf (Página 144)

Configuring Traffic Filters and Protocol Prioritization

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Dial Backup Trafﬁc

When conﬁguring outbound ﬁlters or protocol prioritization on a synchronous line

for which you have conﬁgured a backup line, keep the following considerations in

mind:

• If the primary line is running PPP and the line fails, the router automatically

transfers all the priority queues and outbound ﬁlters you have conﬁgured on

the primary line to the backup line.

• If the primary line is running a wide-area protocol other than PPP and the line

fails, the router does not transfer Data Link protocol prioritization or

outbound ﬁlters to the backup line. You must manually conﬁgure new Data

Link outbound ﬁlters on the backup line after that line is activated. The router

does transfer IP outbound ﬁlters to the backup line, no matter what protocol

was running on the primary line.

Be careful when conﬁguring outbound ﬁlters on the backup line. As soon as the

primary line is reactivated, it uses the priority queues and ﬁlters you conﬁgured

for the backup line. These priorities and ﬁlters may be completely inappropriate

for the protocol running on the primary line.

Using Drop-All Filters

If your ﬁltering strategy involves forwarding most trafﬁc and dropping only

speciﬁed packets, conﬁgure ﬁlters only for the speciﬁc trafﬁc you want to drop.

If your strategy involves blocking most trafﬁc and accepting only speciﬁed

packets (a “ﬁrewall”), begin by deﬁning speciﬁc, higher-precedence ﬁlters to

accept speciﬁed packets. Then add a ﬁlter on the interface to drop all other

packets, a drop-all ﬁlter. (The highest-precedence ﬁlter in a given address range

determines the result of combined ﬁltering within that range.)

A drop-all ﬁlter describes the broadest range of packets you want to block from an

interface. To ensure that all unwanted trafﬁc gets dropped, conﬁgure the drop-all

ﬁlter to contain

• Criteria that appears in every packet of the protocol you want to ﬁlter

• The maximum possible value of the range

• The minimum value of the range

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Avaya Configuring Traffic Filters and Protocol Prioritization Manual do Utilizador Página 144