Excluded ports, Broadcast leaks, Super aggregated vlans – Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide User Manual
Page 370: Trunk group ports and vlan membership, Summary of vlan configuration rules, Leak" through the vlan. refer to
Excluded ports
If you want to prevent a port in a port-based VLAN from ever becoming a member of a protocol, IP
subnet, IPX network, or AppleTalk cable VLAN configured in the port-based VLAN, you can explicitly
exclude the port. You exclude the port when you configure the protocol, IP subnet, IPX network, or
AppleTalk cable VLAN.
Excluded ports do not leak broadcast packets. Refer to
on page 370.
Broadcast leaks
A dynamic port becomes a member of a Layer 3 protocol VLAN when traffic from the VLAN's protocol
is received on the port. After this point, the port remains an active member of the protocol VLAN,
unless the port does not receive traffic from the VLAN's protocol for 20 minutes. If the port does not
receive traffic for the VLAN's protocol for 20 minutes, the port ages out and is no longer an active
member of the VLAN.
To enable a host that has been silent for awhile to send and receive packets, the dynamic ports that
are currently members of the Layer 3 protocol VLAN "leak" Layer 3 broadcast packets to the ports that
have aged out. When a host connected to one of the aged out ports responds to a leaked broadcast,
the port is added to the protocol VLAN again.
To "leak" Layer 3 broadcast traffic, an active port sends 1/8th of the Layer 3 broadcast traffic to the
inactive (aged out) ports.
Static ports do not age out and do not leak broadcast packets.
Super aggregated VLANs
Brocade FastIron devices support Super Aggregated VLANs. You can aggregate multiple VLANs
within another VLAN. This feature allows you to construct Layer 2 paths and channels. This feature is
particularly useful for Virtual Private Network (VPN) applications in which you need to provide a
private, dedicated Ethernet connection for an individual client to transparently reach its subnet across
multiple networks.
For an application example and configuration information, refer to
on page 399.
Trunk group ports and VLAN membership
A trunk group is a set of physical ports that are configured to act as a single physical interface. Each
trunk group port configuration is based on the configuration of the lead port, which is the lowest
numbered port in the group.
If you add a trunk group lead port to a VLAN, all of the ports in the trunk group become members of
that VLAN.
Summary of VLAN configuration rules
A hierarchy of VLANs exists between the Layer 2 and Layer 3 protocol-based VLANs:
• Port-based VLANs are at the lowest level of the hierarchy.
• Layer 3 protocol-based VLANs, IP, IPv6, IPX, AppleTalk, Decnet, and NetBIOS are at the middle
level of the hierarchy.
• IP subnet, IPX network, and AppleTalk cable VLANs are at the top of the hierarchy.
Excluded ports
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