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User Manual
Publication date: July, 2006
Revision A2
68
Symmetric Vlan:
This is a Ingress Rule (Rule 1, The Ingress Filtering Rule 1 is “forward
only packets with VID matching this port’s configured VID”.). For example,
if port 1 receives a tagged packet with VID=100 (VLAN name=VLAN100),
and if Symmetric-Vlan function is enabled, the switch will check if port 1
is a member of VLAN100. If yes, the received packet is forwarded;
otherwise, the received packet is dropped.
Note: If Symmetric is enabled and port 1, for example, receives an untagged packet,
the switch will apply the PVID of port 1 to tag this packet, the packet then will
be forwarded. But if the PVID of port 1 is not 100, the packet will be dropped.
SVL:
While SVL is enable, all VLANs use the same filtering database storing
the membership information of the VLAN to learn or look up the
membership information of the VLAN. While SVL is disable, it means
learning mode is IVL. In this mode, different VLAN uses different filtering
database storing the membership information of the VLAN to learn or
look up the information of a VLAN member.
Double Tag:
Double-tag mode belongs to the tag-based mode, however, it would treat
all frames as the untagged ones, which means that tag with PVID will be
added into all packets. Then, these packets will be forwarded as Tag-
based VLAN. So, the incoming packets with tag will become the double-
tag ones.