Enterasys Networks CSX7000, CSX5500, CSX6000 manual Packet Types, Forwarding Filters

USER’S GUIDE

IP Packet		FILTER
	Discard	Type 3
Conditions	Discard	Type 1
	Forward	Type 4

Packet Types:

Type 1: www,www,www

Type 2: xxx,xxx,xxx

Type 3: yyy,yyy

Type 4: zzz,zzz

Final	Discard All Other Types
Condition

Action:

Discard/Forward

Sample packet passing through a filter

FILTER COMPOSITION

The IP filtering mechanism is composed of three fundamental building blocks:

•Packet Types

The criteria for describing an IP datagram’s contents: IP Source and Destination Addresses, Protocol (TCP, UDP, etc.), Protocol-specific fields (TCP port, etc.). For example, Packet Types can be set up to specify such things as: “all packets arriving from IP Subnetwork X”, “Telnet packets destined for host Y”, or “All RIP packets”. Packet Types are independently defined and may be referenced by multiple filters.

•Conditions

A Packet Type combined with an Action to take when a datagram matches that type. The Actions are DISCARD or FORWARD.

•Filter

An ordered list of Conditions. When an IP datagram passes through a filter, a sequential pass is made through the individual conditions. The first complete match of a Packet Type dictates the action which is applied to the datagram. When the action is DISCARD, the datagram is dropped. The filter also contains a configurable Final Condition which specifies the action to take if no match is found.

TYPES OF FILTERS

Forwarding Filters

A Forwarding Filter is a filter which forwards or discards specific packets according to whether these packets fulfill a list of defined conditions.Forwarding Filters may be applied to packets in one of the following ways:

•Globally: independent of the packet’s input or output path.

•through the Input Network Interface: applies the filter only to packets arriving on a specific

302 CyberSWITCH