Chapter 7
| Spanning Tree Algorithm
Configuring Interface Settings for STA
– 209 –
Administrative path cost cannot be used to directly determine the root port on
a switch. Connections to other devices use IEEE 802.1Q-2005 to determine the
root port as in the following example.
Figure 118: Determining the Root Port
For BPDU messages received by i1 on SW3, the path cost is 0.
For BPDU messages received by i2 on SW3, the path cost is that of i1 on SW2.
The root path cost for i1 on SW3 used to compete for the role of root port is
0 + path cost of i1 on SW3; 0 since i1 is directly connected to the root bridge.
If the path cost of i1 on SW2 is never configured/changed, it is 10000.
Then the root path cost for i2 on SW3 used to compete for the role of root port
is 10000 + path cost of i2 on SW3.
The path cost of i1 on SW3 is also 10000 if not configured/changed.
Then even if the path cost of i2 on SW3 is configured/changed to 0, these ports
will still have the same root path cost, and it will be impossible for i2 to become
the root port just by changing its path cost on SW3.
For RSTP mode, the root port can be determined simply by adjusting the path
cost of i1 on SW2. However, for MSTP mode, it is impossible to achieve this only
by changing the path cost because external path cost is not added in the same
region, and the regional root for i1 is SW1, but for i2 is SW2.
◆
Admin Link Type
– The link type attached to this interface.
■
Point-to-Point – A connection to exactly one other bridge.
■
Shared – A connection to two or more bridges.
■
Auto – The switch automatically determines if the interface is attached to a
point-to-point link or to shared media. (This is the default setting.)
◆
Admin Edge Port
– Since end nodes
cannot
cause forwarding loops, they can
pass directly through to the spanning tree forwarding state. Specifying Edge
Ports provides quicker convergence for devices such as workstations or servers,
retains the current forwarding database to reduce the amount of frame
flooding required to rebuild address tables during reconfiguration events, does
Table 12: Default STA Path Costs
Port Type
Short Path Cost
(IEEE 802.1D-1998)
Long Path Cost
(IEEE 802.1D-2004)
Ethernet
65,535 1,000,000
Fast Ethernet
65,535
100,000
Gigabit Ethernet
10,000
10,000
10G Ethernet
1,000
1,000
Содержание GTL-2881
Страница 30: ...Figures 30 Figure 450 Showing RIP Peer Information 669 Figure 451 Resetting RIP Statistics 670 ...
Страница 34: ...Section I Getting Started 34 ...
Страница 48: ...Section II Web Configuration 48 Unicast Routing on page 651 ...
Страница 151: ...Chapter 4 Interface Configuration VLAN Trunking 151 Figure 69 Configuring VLAN Trunking ...
Страница 152: ...Chapter 4 Interface Configuration VLAN Trunking 152 ...
Страница 229: ...Chapter 8 Congestion Control Automatic Traffic Control 229 Figure 135 Configuring ATC Interface Attributes ...
Страница 230: ...Chapter 8 Congestion Control Automatic Traffic Control 230 ...
Страница 596: ...Chapter 14 Multicast Filtering Multicast VLAN Registration for IPv6 596 ...
Страница 620: ...Chapter 15 IP Configuration Setting the Switch s IP Address IP Version 6 620 ...
Страница 670: ...Chapter 18 Unicast Routing Configuring the Routing Information Protocol 670 Figure 451 Resetting RIP Statistics ...
Страница 672: ...Section III Appendices 672 ...
Страница 678: ...Appendix A Software Specifications Management Information Bases 678 ...
Страница 688: ...Appendix C License Statement GPL Code Statement Notification of Compliance 688 ...
Страница 696: ...Glossary 696 ...
Страница 706: ...GTL 2881 GTL 2882 E112016 ST R01 ...