Page 5 | AlliedWare™ OS How To Note: Hardware Filters
Creating dedicated hardware filters
z
When packets arrive at a customer port of a nested VLAN, the “inner” parameters will
match the attributes of the first tag in the packets. This is because when the packet is
forwarded from the core port, that first tag will have become the inner tag. So, from the
point of view of the nested VLAN, the tag that is on the packet when it arrives into the
customer port is the inner tag.
z
When nested VLANs are disabled, and “inner” parameters have been configured, these
parameters will be applied as though all packets arriving at the switch were double tagged.
In other words, there will be no attempt to make a distinction between “customer” and
“core” ports. So, if the packets arriving at the switch are not double tagged, then the
“inner” parameters will just match on whatever data happens to be in the packets at the
position where an inner tag would have been.
Therefore, when you disable nested VLANs, you should also remove the classifiers.
z
When nested VLANs are being used, the parameters
tpid
and
vlanpriority
cannot be
used in classifiers on filters applied to customer ports.
z
If you attach the classifier to a number of ports, they will all be treated like core ports if
at least one of the ports is a core port.
Creating hardware filters
Once you have created a classifier, create a filter. The filter uses the classifier, and specifies an
action.
add switch hwfilter[=<
filter-id
>] classifier=<
rule-id
>
action={copy|discard|forward|copy,discard|setl2qos}
Note that it is possible, but not required, to specify a ID number for the filter. If you do not
specify an ID, then the filter is simply added to the end of the existing list of filters. However,
if you want to actually insert a filter into a specific position in the list, then you can specify a
filter ID. That way, the filter will be inserted at the position indicated by the filter-id value, and
all the existing filters from that position and above will all move up one position.
For example, imagine you have the following set of filters:
add swi hwfilt class=1 action=xxx
add swi hwfilt class=4 action=xxx
add swi hwfilt class=3 action=xxx
add swi hwfilt class=6 action=xxx
Then, enter the following command:
add swi hwfilt=2 class=8
The new filter will be inserted at position 2 in the list. The previous filter #2 will become
filter #3, the previous filter #3 will become filter #4, and the previous filter #4 will become
filter #5:
add swi hwfilt class=1 action=xxx
add swi hwfilt class=8 action=xxx
add swi hwfilt class=4 action=xxx
add swi hwfilt class=3 action=xxx
add swi hwfilt class=6 action=xxx
