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Page 756 / 998 Scroll up to view Page 751 - 755
L2Filter
Overview
iMG/RG Software Reference Manual (Quality of Service)
7-60
7.2
L2Filter
7.2.1
Overview
The purpose of the L2 Filter module is to provide a mechanism by which inbound traffic can be classified and
acted upon based on its contents.
The module is configured by defining a set of profiles which themselves con-
tain a set of rules.
Each rule defines a packet classification and the appropriate action to take in the event of a
match.
The actions vary from basic operations, such as DROP, to more complex actions such as packet rewrit-
ing.
This mechanism provides a powerful and flexible framework for filtering of traffic in the system.
7.2.1.1 Packet Flow
In order to properly utilize the L2 Filter system, it is important to understand where this module falls in the
general flow of a packet through the system.
The important item to note in the above diagram is that packets are only run through the L2 Filter module in
the event they leave the layer 2 switch bound for the bridge.
This occurs when the CPU requires access to the
packet in order to read it, alter it or route it to another device in the system.
Some examples of these scenar-
ios are the following:
NAT, VLAN translation, usage of the ADSL module, etc.
7.2.1.1.1 Profiles
The profile is the high level container of the L2 Filter system.
The user creates a profile, assigns a series of
rules to that profile and then attaches it to the bridge transport.
Once the L2 Filter system is activated the
packet flow, in the system, is run through the profiles and the appropriate rules are applied.
Multiple profiles
can be configured however only two can be applied to the bridge at any given time.
You can assign one profile
to each direction of packet flow from the bridge (Rx and Tx).
LAN 1
LAN 3
Switch
Bridge
(CPU)
LAN 2
L2 Filter
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L2Filter Command Reference
L2Filter
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iMG/RG Software Reference Manual (Quality of Service)
7.2.1.1.2 Rules
The rule is the workhorse of the L2 Filter system.
A user defines a set of rules which contain one packet clas-
sifier and its associated action.
The packet classifier is an offset / value pair that the filter uses to identify packets
on which to apply a rule.
Several of the basic classifier fields have been pre-defined for use however the user has
the ability to define their own.
7.2.1.1.3 Example
The following is an example of how the L2 Filter module can be used to filter incoming and outgoing DHCP
requests for VLAN 402 on the bridge.
Example
l2filter add fieldType udpDstPort base udp_header offset 2 mask 0xffff
l2filter add fieldType ipProtocol base ip_header offset 9 mask 0xff
l2filter add profile bridge_rx
l2filter add profile bridge_tx
l2filter add rule Vlan402DhcpServerRx
l2filter rule Vlan402DhcpServerRx add action drop
l2filter rule Vlan402DhcpServerRx add field udpDstPort EQ 67
l2filter rule Vlan402DhcpServerRx add field packetvid EQ 402
l2filter add rule Vlan402DhcpServerTx
l2filter rule Vlan402DhcpServerTx add action drop
l2filter rule Vlan402DhcpServerTx add field udpDstPort EQ 67
l2filter rule Vlan402DhcpServerTx add field packetvid EQ 402
l2filter profile bridge_rx attach rule Vlan402DhcpServerRx
l2filter profile bridge_tx attach rule Vlan402DhcpServerTx
transport attach default l2filter profile bridge_rx Rx
transport attach default l2filter profile bridge_tx Tx
transport set default l2filter state enabled
7.2.2
L2Filter Command Reference
7.2.2.1 L2 Filter CLI commands
The table below lists the
l2filter
commands provided by the CLI:
TABLE 7-4
L2filter commands
Commands
Fiber
A
Fiber
B
Fiber
C
Fiber
D
Fiber
E
Modul
ar
ADSL
A
ADSL
B
ADSL
C
L2FILTER ADD FIELDTYPE
X
X
X
X
X
X
X
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L2Filter
L2Filter Command Reference
iMG/RG Software Reference Manual (Quality of Service)
7-62
L2FILTER ADD PROFILE
X
X
X
X
X
X
X
L2FILTER ADD RULE
X
X
X
X
X
X
X
L2FILTER CLEAR FIELDTYPES
X
X
X
X
X
X
X
L2FILTER CLEAR PROFILES
X
X
X
X
X
X
X
L2FILTER CLEAR RULES
X
X
X
X
X
X
X
L2FILTER DELETE FIELDTYPE
X
X
X
X
X
X
X
L2FILTER DELETE RULE
X
X
X
X
X
X
X
L2FILTER DELETE PROFILE
X
X
X
X
X
X
X
L2FILTER LIST FIELDTYPES
X
X
X
X
X
X
X
L2FILTER LIST PROFILES
X
X
X
X
X
X
X
L2FILTER LIST RULES
X
X
X
X
X
X
X
L2FILTER SHOW PROFILE
X
X
X
X
X
X
X
L2FILTER SHOW RULE
X
X
X
X
X
X
X
L2FILTER SHOW FIELDTYPE
X
X
X
X
X
X
X
L2FILTER PROFILE ATTACH RULE
X
X
X
X
X
X
X
L2FILTER PROFILE DETACH RULE
X
X
X
X
X
X
X
L2FILTER RULE ADD ACTION
X
X
X
X
X
X
X
L2FILTER RULE ADD FIELD
X
X
X
X
X
X
X
L2FILTER RULE LIST ACTIONS
X
X
X
X
X
X
X
L2FILTER RULE LIST FIELDS
X
X
X
X
X
X
X
L2FILTER RULE DELETE ACTION
X
X
X
X
X
X
X
L2FILTER RULE DELETE FIELD
X
X
X
X
X
X
X
L2FILTER SET RULE ENABLE
X
X
X
X
X
X
X
L2FILTER SET RULE DISABLE
X
X
X
X
X
X
X
TABLE 7-4
L2filter commands
Commands
Fiber
A
Fiber
B
Fiber
C
Fiber
D
Fiber
E
Modul
ar
ADSL
A
ADSL
B
ADSL
C
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L2Filter Command Reference
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iMG/RG Software Reference Manual (Quality of Service)
7.2.2.1.1 L2FILTER ADD FIELDTYPE
Syntax
L2FILTER ADD FIELDTYPE <name> BASE <base_value> OFFSET
<offset_value> MASK <mask_value>
Description
This command allows the user to create their own filter field types.
Options
The following table gives the range of values for each option that can be specified with
this command and a default value (if applicable).
Example
--> l2filter add fieldType test_field base ethernet_header offset 10 mask 0xf
See also
L2FILTER SHOW FIELDTYPE
7.2.2.1.2 L2FILTER ADD PROFILE
Syntax
L2FILTER ADD PROFILE <name>
Description
This command adds a profile to the L2 filter module.
Options
The following table gives the range of values for each option that can be specified with
this command and a default value (if applicable).
Example
--> l2filter add profile InboundTraffic
See also
L2FILTER SHOW PROFILE
7.2.2.1.3 L2FILTER ADD RULE
Syntax
L2FILTER ADD RULE <name> STAGE <stage> ORDER <order>
Description
This command adds a rule to the module that can be attached to a profile.
Option
Description
Default Value
name
The name of the new field type
n/a
base_value
The location in the packet to offset from
n/a
offset_value
The offset distance from the base to compare
n/a
mask_value
The mask to apply at the offset
n/a
Option
Description
Default Value
name
The name of the rule
n/a
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L2Filter
L2Filter Command Reference
iMG/RG Software Reference Manual (Quality of Service)
7-64
Options
The following table gives the range of values for each option that can be specified with
this command and a default value (if applicable).
Example
--> l2filter add rule TestRule stage 1 order 2
See also
L2FILTER SHOW RULE
7.2.2.1.4 L2FILTER CLEAR FIELDTYPES
Syntax
L2FILTER CLEAR FIELDTYPES
Description
This command will clear all the available field types from the system.
Example
--> l2filter clear fieldtypes
See also
L2FILTER LIST FIELDTYPES
7.2.2.1.5 L2FILTER CLEAR PROFILES
Syntax
L2FILTER CLEAR PROFILES
Description
This command will clear all the available profiles from the system.
Example
--> l2filter clear profiles
See also
L2FILTER LIST PROFILES
7.2.2.1.6 L2FILTER CLEAR RULES
Syntax
L2FILTER CLEAR RULES
Description
This command will clear the available rules from the system.
Example
--> l2filter clear rules
See also
L2FILTER LIST RULES
7.2.2.1.7 L2FILTER DELETE FIELDTYPE
Syntax
L2FILTER DELETE FIELDTYPE <name>
Option
Description
Default Value
name
The name of the rule
n/a
stage
The stage of processing in which this rule will be applied
1
order
The order in the stage when this rule will be applied
1

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