Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 815)

Brocade 6910 Ethernet Access Switch Configuration Guide 765
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Configuring Global Settings for STA
36
• Maximum Age – The maximum time (in seconds) a device can wait without receiving a
configuration message before attempting to reconverge. All device ports (except for designated
ports) should receive configuration messages at regular intervals. Any port that ages out STA
information (provided in the last configuration message) becomes the designated port for the
attached LAN. If it is a root port, a new root port is selected from among the device ports
attached to the network. (References to “ports” in this section mean “interfaces,” which
includes both ports and trunks.)
• Default: 20
• Minimum: The higher of 6 or [2 x (Hello Time + 1)]
• Maximum: The lower of 40 or [2 x (Forward Delay - 1)]
• Forward Delay – The maximum time (in seconds) this device will wait before changing states
(i.e., discarding to learning to forwarding). This delay is required because every device must
receive information about topology changes before it starts to forward frames. In addition,
each port needs time to listen for conflicting information that would make it return to a
discarding state; otherwise, temporary data loops might result.
• Default: 15
• Minimum: The higher of 4 or [(Max. Message Age / 2) + 1]
• Maximum: 30
RSTP does not depend on the forward delay timer in most cases. It is able to confirm that a
port can transition to the forwarding state without having to rely on any timer configuration.
To achieve fast convergence, RSTP relies on the use of edge ports, and automatic detection of
point-to-point link types, both of which allow a port to directly transition to the forwarding state.
Configuration Settings for MSTP
• Max Instance Numbers – The maximum number of MSTP instances to which this switch can be
assigned.
• Configuration Digest – An MD5 signature key that contains the VLAN ID to MST ID mapping
table. In other words, this key is a mapping of all VLANs to the CIST.
• Region Revision
15
– The revision for this MSTI. (Range: 0-65535; Default: 0)
• Region Name
15
– The name for this MSTI. (Maximum length: 32 characters; switch’s MAC
address)
• Max Hop Count – The maximum number of hops allowed in the MST region before a BPDU is
discarded. (Range: 1-40; Default: 20)
Interface
To configure global STA settings:
1. Click Spanning Tree, STA.
2. Select Configure Global from the Step list.
3. Select Configure from the Action list.
4. Modify any of the required attributes. Note that the parameters displayed for the spanning tree
types (STP, RSTP, MSTP) varies as described in the preceding section.
5. Click Apply
15. The MST name and revision number are both required to uniquely identify an MST region.