Specifications

Tunneling (VMANs)
ExtremeWare XOS 11.0 Concepts Guide 93
You can display statistics for multiple VLANs by entering the name of each VLAN on the command
line.
Displaying Protocol Information
To display protocol information, use the following command:
show protocol {<name>}
This show command displays protocol information, which includes:
• Protocol name
• Type
• Value
Tunneling (VMANs)
You can “tunnel” any number of 802.1Q and/or Cisco ISL VLANs into a single VLAN that can be
switched through an Extreme Ethernet infrastructure. A given tunnel is completely isolated from other
tunnels or VLANs. For the MAN provider, the tagging numbers and methods used by the customer are
transparent to the provider.
You establish a private path through the public network using the Extreme Networks VMAN feature,
which creates a bidirectional virtual data connection. A given tunnel switches Layer 2 traffic; the
specified tunnel traffic is completely isolated from other traffic or tunnels. This feature is useful in
building transparent private networks, or VMANs, that provide point-to-point or point-to-multipoint
connectivity across an Ethernet infrastructure. Using encapsulation, the routing nodes in the public
network are unaware that the transmission is part of a VMAN connection.
To use the VMAN feature, you configure an encapsulation for all the traffic on the specified VMAN.
The encapsulation allows the VMAN traffic to be switched over an Layer 2 infrastructure. To
encapsulate the packet, the system adds a VMAN header that forms an outer VLAN header to the
Ethernet frame. The traffic is switched through the infrastructure based on the VMAN header. The
egress port of the entire VMAN removes the VMAN header, and the frame proceeds through the rest of
the network with the original VLAN header.
VMAN is enabled on the ports in the tunnel. When VMAN is enabled on a network port, that port adds
the VMAN tag to all ingressing frames, whether the frame is originally tagged or untagged. The
Ethernet type configured for the VMAN header applies to the entire switch; this value cannot be
configured per port. The default VMAN Ethernet type on Extreme devices is 88a8.
If your VMAN transits a third-party device (other than an Extreme Networks device), you must
configure the EtherType for the VMAN tag as 8100 for third-party switches (or as the Ethernet type that
the third-party device uses).
Within an Extreme Networks switch, the system also examines the packet’s inner 802.1p tag and then
directs the packet to the appropriate egress queue on the egress port. See Chapter 8 for more
information on Quality of Service (QoS) and configuring the 802.1p replacement feature.