Verilink 9000 Series (34-00271) Product Manual - Manual (Page 302)

280 C HAPTER 17: B RIDGE
Multicast MAC Address
The Multicast MAC address parameter is the 6-byte long MAC address recognized
by the bridge as the group address for BPDU transfer between bridges. When a
bridge is sending a BPDU frame, all the other bridges should receive the BPDU
frame. The sending bridge inserts this MAC address in the destination field of the
frame sent to the LAN.
The default value is defined in the 802.1d standard.
LAN Path Cost
The LAN Path Cost parameter is used in the spanning tree algorithm to quantify
the efficiency path of the LAN compared to the WAN Path Cost parameter. The
range for this field is 1 to 65535 Mbps and the default is 100.
WAN Path Cost
The WAN Path Cost parameter is used in the spanning tree algorithm to quantify
the efficiency path of the WAN compared to the LAN Path Cost parameter. The
selections are 1 to 65535 Mbps and the default is 667.
Bridge ID
For the spanning tree algorithm to work properly, every bridge in the network
should have its own identifier. The bridge identifier is eight bytes long and it is
constituted of two parts: A bridge priority and its own MAC address. The bridge
with the smaller identifier, when compared as two binary numbers, is considered as
the bridge with the higher priority. The bridge with the higher priority is selected
as the root bridge and sits on the top of the spanning tree. The choice of the
bridge’s identifier influences the network performance. Because the MAC address
part of the identifier is fixed in the hardware interface, this field is used to define
the bridge’s priority in the network. The selections range from 0 to 255.
Hello Timer
The Hello Timer parameter specifies the interval between broadcasting Bridge
Protocol Data Unit (BPDU) frames by the Root bridge. This value defines the
period needed to detect a network topology change and to inform all bridges of
this modification. A network modification includes a bridge failure, a port link
failure, the addition of a new bridge or anything that could modify the data path
between bridges. The Max Age Timer must be at least three times greater than the
Hello Timer. The selections are 1 to 65535 seconds and the default is 2. A
recommended value for a stable network is 20.
Forward Delay
The Forward Delay parameter corresponds to the interval, in seconds, of each of
the four states of the spanning tree algorithm: blocking, listening, learning, and
forwarding. The selections are 1 to 65535. The default is 15 seconds.
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