Enterasys Networks ENTERASYS ATX - Manual (Page 55)

Editing the Port Filters Table 4-5
Using ATX Port Filtering
Adding a New Filter
The ATX allows you to create up to 100 Port filters (total for all connected ports).
To add a new filter to the ATX or modify a previously configured Port Filter:
1. In the Port field, type in the interface number of the port to which this filter will
apply.
2. Click on the Type button to select the filter type: ENTRY (the default type)
EXIT, MENTRY, or MEXIT.
• Entry filters are used to screen incoming traffic at a receive port. They are
applied to packets
as they are being received by a specified port.
• Exit filters are used to screen outgoing traffic from the receive port. They
are applied to packets
after they are received and forwarded by a specified
port.
• Mirror Entry filters are used to screen incoming traffic at a receive port that
supports and is using port mirroring. They are applied to packets
as they
are being received by a specified port.
• Mirror Exit filters are used to screen outgoing traffic from the receive port
when the port supports and is using port mirroring. They are applied to
packets
after they are received and forwarded by a specified port.
3. Click on the Pseudo button to indicate whether you want to create a pseudo
filter.
• YES indicates that you wish to create a pseudo filter — one which gathers
statistics on all packets that have met the filtering criteria, but does not
actually filter them. Pseudo filters are useful if you want to determine the
effects of a filter without actually implementing it, or for monitoring traffic
!
CAUTION
Remember that the ATX’s performance may be adversely affected if you define a large
number of Port filters. Because the ATX has to decode packet data further than it would if
no filters were established, the forwarding rate of traffic may be slowed as packets are
buffered and decoded.
Typically, if you create Bridge Address Table filters or only a small number of Port filters,
the forwarding rate of the ATX will not be affected; however, the more complex or greater
number of Port filters that you create, the more traffic flow will be affected. For this reason,
it is good practice to delete filters from the Port Filtering Table when they are no longer
needed.
NOTE
If you are also performing Work Group Configuration on your ATX, remember that each
Work Group that you establish will reduce the number of Port filters you can configure at
a one-to-one ratio.