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STP Timers, BPDU Comparing Principle in STP mode, STP Generation

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Figure 7-1 Basic STP diagram ¾ STP Timers Hello Time: Hello Time ranges from 1 to 10 seconds. It specifies the interval to send BPDU packets. It is used to test the links. Max. Age: Max. Age ranges from 6 to 40 seconds. It specifies the maximum time the switch can wait without receiving a BPDU before attempting to reconfigure. Forward Delay: Forward Delay ranges from 4 to 30 seconds. It specifies the time for the port to transit its state after the network topology is changed. When the STP regeneration caused by network malfunction occurs, the STP structure will get some corresponding change. However, as the new configuration BPDUs cannot be spread in the whole network at once, the temporal loop will occur if the port transits its state immediately. Therefore, STP adopts a state transit mechanism, that is, the new root port and the designated port begins to forward data after twice forward delay, which ensures the new configuration BPDUs are spread in the whole network. ¾ BPDU Comparing Principle in STP mode Assuming two BPDUs: BPDU X and BPDU Y If the root bridge ID of X is smaller than that of Y, X is superior to Y. If the root bridge ID of X equals that of Y, but the root path cost of X is smaller than that of Y, X is superior to Y. If the root bridge ID and the root path cost of X equal those of Y, but the bridge ID of X is smaller than that of Y, X is superior to Y. If the root bridge ID, the root path cost and bridge ID of X equal those of Y, but the port ID of X is smaller than that of Y, X is superior to Y. ¾ STP Generation z In the beginning In the beginning, each switch regards itself as the root, and generates a configuration BPDU for each port on it as a root, with the root path cost being 0, the ID of the designated bridge being that of the switch, and the designated port being itself. 71

Section	Page
Package Contents	8
Chapter 1 About this Guide	9
1.1 Intended Readers	9
1.2 Conventions	9
1.3 Overview of This Guide	9
Chapter 2 Introduction	13
2.1 Overview of the Switch	13
2.2 Main Features	13
2.3 Appearance Description	14
2.3.1 Front Panel	14
2.3.2 Rear Panel	15
Chapter 3 Login to the Switch	16
3.1 Login	16
3.2 Configuration	16
Chapter 4 System	18
4.1 System Info	18
4.1.1 System Summary	18
4.1.2 Device Description	20
4.1.3 System Time	20
4.1.4 System IP	22
4.2 User Manage	23
4.2.1 User Table	23
4.2.2 User Config	23
4.3 System Tools	25
4.3.1 Config Restore	25
4.3.2 Config Backup	25
4.3.3 Firmware Upgrade	26
4.3.4 System Reboot	27
4.3.5 System Reset	27
4.4 Access Security	27
4.4.1 Access Control	27
4.4.2 SSL Config	29
4.4.3 SSH Config	30
Chapter 5 Switching	36
5.1 Port	36
5.1.1 Port Config	36
5.1.2 Port Mirror	37
5.1.3 Port Security	39
5.2 LAG	40
5.2.1 LAG Table	41
5.2.2 Static LAG	42
5.2.3 LACP Config	43
5.3 Traffic Monitor	45
5.3.1 Traffic Summary	45
5.3.2 Traffic Statistics	46
5.4 MAC Address	47
5.4.1 Address Table	48
5.4.2 Static Address	50
5.4.3 Dynamic Address	51
5.4.4 Filtering Address	53
Chapter 6 VLAN	55
6.1 802.1Q VLAN	56
6.1.1 VLAN Config	58
6.1.2 Port Config	60
6.2 MAC VLAN	62
6.3 Protocol VLAN	63
6.3.1 Protocol Group Table	66
6.3.2 Protocol Group	66
6.3.3 Protocol Template	67
6.4 Application Example for 802.1Q VLAN	68
6.5 Application Example for MAC VLAN	70
6.6 Application Example for Protocol VLAN	71
6.7 GVRP	73
Chapter 7 Spanning Tree	77
7.1 STP Config	82
7.1.1 STP Config	82
7.1.2 STP Summary	84
7.2 Port Config	84
7.3 MSTP Instance	86
7.3.1 Region Config	86
7.3.2 Instance Config	87
7.3.3 Instance Port Config	88
7.4 STP Security	90
7.4.1 Port Protect	90
7.4.2 TC Protect	93
7.5 Application Example for STP Function	93
Chapter 8 Multicast	97
8.1 IGMP Snooping	99
8.1.1 Snooping Config	100
8.1.2 Port Config	101
8.1.3 VLAN Config	102
8.1.4 Multicast VLAN	104
8.2 Multicast IP	107
8.2.1 Multicast IP Table	108
8.2.2 Static Multicast IP	108
8.3 Multicast Filter	109
8.3.1 IP-Range	110
8.3.2 Port Filter	111
8.4 Packet Statistics	112
Chapter 9 QoS	114
9.1 DiffServ	117
9.1.1 Port Priority	117
9.1.2 Schedule Mode	118
9.1.3 802.1P Priority	119
9.1.4 DSCP Priority	119
9.2 Bandwidth Control	121
9.2.1 Rate Limit	121
9.2.2 Storm Control	122
9.3 Voice VLAN	123
9.3.1 Global Config	125
9.3.2 Port Config	126
9.3.3 OUI Config	127
Chapter 10 ACL	129
10.1 Time-Range	129
10.1.1 Time-Range Summary	129
10.1.2 Time-Range Create	130
10.1.3 Holiday Config	131
10.2 ACL Config	131
10.2.1 ACL Summary	132
10.2.2 ACL Create	132
10.2.3 MAC ACL	133
10.2.4 Standard-IP ACL	134
10.2.5 Extend-IP ACL	134
10.3 Policy Config	136
10.3.1 Policy Summary	136
10.3.2 Policy Create	137
10.3.3 Action Create	137
10.4 Policy Binding	138
10.4.1 Binding Table	138
10.4.2 Port Binding	139
10.4.3 VLAN Binding	139
10.5 Application Example for ACL	140
Chapter 11 Network Security	143
11.1 IP-MAC Binding	143
11.1.1 Binding Table	143
11.1.2 Manual Binding	144
11.1.3 ARP Scanning	146
11.1.4 DHCP Snooping	147
11.2 ARP Inspection	153
11.2.1 ARP Detect	157
11.2.2 ARP Defend	158
11.2.3 ARP Statistics	159
11.3 DoS Defend	160
11.4 802.1X	162
11.4.1 Global Config	166
11.4.2 Port Config	168
11.4.3 Radius Server	169
Chapter 12 SNMP	171
12.1 SNMP Config	173
12.1.1 Global Config	173
12.1.2 SNMP View	174
12.1.3 SNMP Group	175
12.1.4 SNMP User	176
12.1.5 SNMP Community	178
12.2 Notification	180
12.3 RMON	182
12.3.1 History Control	183
12.3.2 Event Config	183
12.3.3 Alarm Config	184
Chapter 13 Cluster	187
13.1 NDP	188
13.1.1 Neighbor Info	188
13.1.2 NDP Summary	189
13.1.3 NDP Config	191
13.2 NTDP	192
13.2.1 Device Table	192
13.2.2 NTDP Summary	193
13.2.3 NTDP Config	194
13.3 Cluster	196
13.3.1 Cluster Summary	196
13.3.2 Cluster Config	197
13.4 Application Example for Cluster Function	199
Chapter 14 Maintenance	202
14.1 System Monitor	202
14.1.1 CPU Monitor	202
14.1.2 Memory Monitor	203
14.2 Log	204
14.2.1 Log Table	205
14.2.2 Local Log	205
14.2.3 Remote Log	206
14.2.4 Backup Log	207
14.3 Device Diagnose	208
14.3.1 Cable Test	208
14.3.2 Loopback	209
14.4 Network Diagnose	209
14.4.1 Ping	209
14.4.2 Tracert	210
Appendix A: Specifications	212
Appendix B: Configuring the PCs	213
Appendix C: Load Software using FTP	216
Appendix D: 802.1X Client Software	221

Match case Limit results 1 per page

Figure 7-1 Basic STP diagram

STP Timers

Hello Time:

Hello Time ranges from 1 to 10 seconds. It specifies the interval to send BPDU packets. It is used

to test the links.

Max. Age:

Max. Age ranges from 6 to 40 seconds. It specifies the maximum time the switch can wait without

receiving a BPDU before attempting to reconfigure.

Forward Delay:

Forward Delay ranges from 4 to 30 seconds. It specifies the time for the port to transit its state

after the network topology is changed.

When the STP regeneration caused by network malfunction occurs, the STP structure will get

some corresponding change. However, as the new configuration BPDUs cannot be spread in the

whole network at once, the temporal loop will occur if the port transits its state immediately.

Therefore, STP adopts a state transit mechanism, that is, the new root port and the designated

port begins to forward data after twice forward delay, which ensures the new configuration BPDUs

are spread in the whole network.

BPDU Comparing Principle in STP mode

Assuming two BPDUs: BPDU X and BPDU Y

If the root bridge ID of X is smaller than that of Y, X is superior to Y.

If the root bridge ID of X equals that of Y, but the root path cost of X is smaller than that of Y, X is

superior to Y.

If the root bridge ID and the root path cost of X equal those of Y, but the bridge ID of X is smaller

than that of Y, X is superior to Y.

If the root bridge ID, the root path cost and bridge ID of X equal those of Y, but the port ID of X is

smaller than that of Y, X is superior to Y.

STP Generation

In the beginning

In the beginning, each switch regards itself as the root, and generates a configuration BPDU for

each port on it as a root, with the root path cost being 0, the ID of the designated bridge being that

of the switch, and the designated port being itself.