HP 6120XG HP ProCurve Series 6120 Blade Switches Advanced Traffic Management G - Page 111

MSTP Structure, Hello Time, Forward Delay, - cross connect examples

Page 111 highlights

Multiple Instance Spanning-Tree Operation 802.1s Multiple Spanning Tree Protocol (MSTP) In a mesh environment, the default MSTP timer settings (Hello Time and Forward Delay) are usually adequate for MSTP operation. Because a packet crossing a mesh may traverse several links within the mesh, using smallerthan-default settings for the MSTP Hello Time and Forward Delay timers can cause unnecessary topology changes and end-node connectivity problems. For MSTP information beyond what is provided in this manual, refer to the IEEE 802.1s standard. MSTP Structure MSTP maps active, separate paths through separate spanning tree instances and between MST regions. Each MST region comprises one or more MSTP switches. Note that MSTP recognizes an STP or RSTP LAN as a distinct spanning-tree region. Common and Internal Spanning Tree (CIST) MST Region IST Instance MSTI (Optional) MSTI (Optional) Common Spanning Tree (CST) Switch Running STP Switch Running STP Switch Running STP MST Region IST Instance Switch Running RSTP Switch Running RSTP Switch Running RSTP MSTI (Optional) MSTI (Optional) MSTI (Optional) Figure 4-2. Example of MSTP Network with Legacy STP and RSTP Devices Connected 4-7

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 154
  • 155
  • 156
  • 157
  • 158
  • 159
  • 160
  • 161
  • 162
  • 163
  • 164
  • 165
  • 166
  • 167
  • 168
  • 169
  • 170
  • 171
  • 172
  • 173
  • 174
  • 175
  • 176
  • 177
  • 178
  • 179
  • 180
  • 181
  • 182
  • 183
  • 184
  • 185
  • 186
  • 187
  • 188
  • 189
  • 190
  • 191
  • 192
  • 193
  • 194
  • 195
  • 196
  • 197
  • 198
  • 199
  • 200
  • 201
  • 202
  • 203
  • 204
  • 205
  • 206
  • 207
  • 208
  • 209
  • 210
  • 211
  • 212
  • 213
  • 214
  • 215
  • 216
  • 217
  • 218
  • 219
  • 220
  • 221
  • 222
  • 223
  • 224
  • 225
  • 226
  • 227
  • 228
  • 229
  • 230
  • 231
  • 232
  • 233
  • 234
  • 235
  • 236
  • 237
  • 238
  • 239
  • 240
  • 241
  • 242
  • 243
  • 244
  • 245
  • 246
  • 247
  • 248
  • 249
  • 250
  • 251
  • 252
  • 253
  • 254
  • 255
  • 256
  • 257
  • 258
  • 259
  • 260
  • 261
  • 262
  • 263
  • 264
  • 265
  • 266
  • 267
  • 268
  • 269
  • 270
  • 271
  • 272
  • 273
  • 274
  • 275
  • 276
  • 277
  • 278
  • 279
  • 280
  • 281
  • 282
  • 283
  • 284
  • 285
  • 286
  • 287
  • 288

4-7
Multiple Instance Spanning-Tree Operation
802.1s Multiple Spanning Tree Protocol (MSTP)
In a mesh environment, the default MSTP timer settings (
Hello Time
and
Forward Delay
) are usually adequate for MSTP operation. Because a packet
crossing a mesh may traverse several links within the mesh, using smaller-
than-default settings for the MSTP
Hello Time
and
Forward Delay
timers can
cause unnecessary topology changes and end-node connectivity problems.
For MSTP information beyond what is provided in this manual, refer to the
IEEE 802.1s standard.
MSTP Structure
MSTP maps active, separate paths through separate spanning tree instances
and between MST regions. Each MST region comprises one or more MSTP
switches. Note that MSTP recognizes an STP or RSTP LAN as a distinct
spanning-tree region.
Figure 4-2.
Example of MSTP Network with Legacy STP and RSTP Devices
Connected
IST
Instance
MSTI
(Optional)
MSTI
(Optional)
IST
Instance
MSTI
(Optional)
MSTI
(Optional)
MSTI
(Optional)
Switch
Running STP
Switch
Running STP
Switch
Running STP
Switch
Running RSTP
Switch
Running RSTP
Switch
Running RSTP
Common Spanning Tree (CST)
MST Region
MST Region
Common and Internal Spanning Tree (CIST)