3Com CoreBuilder 3500, Руководство по внедрению, Страница: 244 / 592

244 C
HAPTER
10: P
ACKET
F
ILTERING
For example, port 1 has a packet filter using the DPGM assigned to the
rxAll path of port 1 and a broadcast frame is received on port 1. The
bridge determines that the frame will be flooded to the VLAN ports 2-5.
The filter is processed 4 times:
1 Once for the RX port 1 - TX port 2 pair
2 Once for the RX port 1 - TX port 3 pair
3 Once for the RX port 1 - TX port 4 pair
4
Once for the RX port 1 - TX port 5 pair
Use the Standard Port Group filter to contain broadcast, multicast, and
flooded frames:
pushSPGM
pushDPGM
and
If ports 1-3 are in port group 1, 4-5 are in port group 2, and the rxAll path
filter is applied to 1-5, then the appropriate filtering restricts the flooding
to the corresponding port group.
Table 35 and Table 36 show how each port pair filters or does not filter a
broadcast frame that is received on port 1 and destined for ports 2,3,4,5:
The result is that the frame is flooded to ports 2,3, and the frame is
filtered from ports 4,5.
Table 35 Port Group Mask Table
Port Mask
1 0x00000001
2 0x00000001
3 0x00000001
4 0x00000002
Table 36 Filter Processing for Frame Flooded from Port 1 to Ports 2-5
Port Pair SPGM DPGM Filter R
esult
1 and 2 0x00000001 0x00000001 0x00000001 - ACCEPTED.
1 and 3 0x00000001 0x00000001 0x00000001 - ACCEPTED.
1 and 4 0x00000001 0x00000002 0x00000000 - FILTERED.
1 and 5 0x00000001 0x00000002 0x00000000 - FILTERED.