DCBX overview

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IEEE 802.1 organizational TLV set. This set provides information to detect mismatched settings between local and remote devices. A trap or event can be reported once a mismatch is detected. This is an optional TLV. This set includes the following TLVs:

-Port VLANID TLV—Indicates the port VLAN ID (PVID) that is associated with an untagged or priority tagged data frame received on the VLAN port.

-PPVLAN ID TLV—Indicates the port- and protocol--based VLAN ID (PPVID) that is associated with an untagged or priority tagged data frame received on the VLAN port. The TLV supports a “flags” field that indicates whether the port is capable of supporting port- and protocol-based VLANs (PPVLANs) and whether one or more PPVLANs are enabled. The number of PPVLAN ID TLVs in a Link Layer Discovery Protocol Data Unit (LLDPDU) corresponds to the number of the PPVLANs enabled on the port.

-VLAN name TLV—Indicates the assigned name of any VLAN on the device. If the LAN device supports RFC-2674, the value equals the “dot1QVLANStaticName” object. The number of VLAN name TLVs in an LLDPDU corresponds to the number of VLANs enabled on the port.

-Protocol identity TLV—Indicates the set of protocols that are accessible at the device's port. The protocol identity field in the TLV contains a number of octets after the Layer 2 address that can enable the receiving device to recognize the protocol. For example, a device that wishes to advertise the spanning tree protocol includes at least eight octets: 802.3 length (two octets), LLC addresses (two octets), 802.3 control (one octet), protocol ID (two octets), and the protocol version (one octet).

IEEE 802.3 organizational TLV set. This is an optional TLV set. This set includes the following TLVs:

-MAC/PHY configuration/status TLV—Indicates duplex and bit rate capabilities and the current duplex and bit rate settings of the local interface. It also indicates whether the current settings were configured through auto-negotiation or through manual configuration.

-Power through media dependent interface (MDI) TLV—Indicates the power capabilities of the LAN device.

-Link aggregation TLV—Indicates whether the link (associated with the port on which the LLDPDU is transmitted) can be aggregated. It also indicates whether the link is currently aggregated and provides the aggregated port identifier if the link is aggregated.

-Maximum Ethernet frame size TLV—Indicates the maximum frame size capability of the device’s MAC and PHY implementation.

Brocade extension TLV set. This set is used to identify vendor-specific information. This set includes the following TLVs:

-Link Vendor/Version TLV—Indicates the vendor for the switch, host, or router where the port resides.

-Primitive supported/version TLV—Indicates where the link-level primitives are supported (if supported) and the link-level primitive version.

DCBX overview

Storage traffic requires a lossless communication which is provided by CEE. The Data Center Bridging (DCB) Capability Exchange Protocol (DCBX) is used to exchange CEE-related parameters with neighbors to achieve more efficient scheduling and a priority-based flow control for link traffic.

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Brocade Communications Systems 53-1002163-02 manual Dcbx overview