
Examples and Implementation Notes
308645-14.00 Rev 00
B-11
Implementation Notes
This section contains notes about the following:
• Filtering Outbound Frame Relay Traffic
• Filtering over a Dial Backup Line
• Using a Drop-All Filter As a Firewall
• Using Outbound Traffic Filters for LAN Protocols
Filtering Outbound Frame Relay Traffic
When creating outbound filters for Frame Relay traffic, keep in mind that Frame
Relay packets in the Low queue have the discard eligible (DE) bit set by default.
The DE bit is off by default in Frame Relay packets in the Normal and High
queues.
You can change the default setting of the DE bit for packets in the Low and
Normal queues using the Edit Protocol Priority Interface window. See “Enabling
Protocol Prioritization” on page 2-9.
Filtering over a Dial Backup Line
When configuring protocol prioritization on a synchronous interface on which you
have configured a dial backup line, consider the following:
• If the primary line is running PPP and the line fails, the router automatically
transfers all of the priority queues and outbound traffic filters you have
configured on the primary line to the backup line.
• If the primary line is running a WAN protocol other than PPP and fails:
-- The router transfers IP outbound traffic filters to the backup line,
regardless of which protocol was running on the primary line.
-- The router does not transfer data link protocol prioritization or outbound
traffic filters to the backup line. You must manually configure new data
link outbound traffic filters on the backup line after that line is activated.
• Be careful when configuring outbound traffic filters on a backup line. As soon
as the primary line is reactivated, it uses the priority queues and filters you
configured for the backup line. These priority queues and filters may be
completely inappropriate for the protocol running on the primary line.
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