Multiple spanning tree instance (msti), Figure 180: vlan fragmentation with stp or rstp, Blocked port – Allied Telesis AT-S63 User Manual
Page 545: Class 1 laser product, L/a d/c d/c l/a d/c l/a
AT-S63 Management Software Menus Interface User’s Guide
Section V: Spanning Tree Protocols
545
Multiple
Spanning Tree
Instance (MSTI)
The individual spanning trees in MSTP are referred to as Multiple
Spanning Tree Instances (MSTIs). A MSTI can span any number of
AT-9400 Series switches, and an AT-9400 Series switch can support up to
16 MSTIs at a time.
To create a MSTI, you first assign it a number, referred to as the MSTI ID.
The range is 1 to 15. (The switch is shipped with a default MSTI with an
MSTI ID of 0. This default spanning tree instance is discussed later in
“Common and Internal Spanning Tree (CIST)” on page 552.)
After you have selected an MSTI ID, you need to define the scope of the
MSTI by assigning one or more VLANs to it. An instance can contain any
number of VLANs, but a VLAN can belong to only one MSTI at a time.
Following are several examples. Figure 180 illustrates two AT-9400 Series
switches, each containing the two VLANs Sales and Production. The two
parts of each VLAN are connected with a direct link using untagged ports
on both switches. If the switches were running STP or RSTP, one of the
links would be blocked because the links constitute a physical loop. Which
link would be blocked depends on the STP or RSTP bridge settings. In
Figure 180, the link between the two parts of the Production VLAN is
blocked, resulting in a loss of communications between the two parts of
the Production VLAN.
Figure 180. VLAN Fragmentation with STP or RSTP
Blocked Port
FAULT
RPS
MASTER
POWER
CLASS 1
LASER PRODUCT
STATUS
TERMINAL
PORT
1
3
5
7
9
11
2
4
6
8
10
12
13
15
17
19
21
23R
14
16
18
20
22
24R
AT-9424T/SP
Gigabit Ethernet Switch
1
3
5
7
9
11
13
15
17
19
21
23R
2
4
6
8
10
12
14
16
18
20
22
24R
23
24
L/A
D/C
D/C
L/A
D/C
L/A
1000 LINK / ACT
HDX / COL
FDX
10/100 LINK / ACT
PORT ACTIVITY
L/A
1000 LINK / ACT
SFP
SFP
24
SFP
23
FAULT
RPS
MASTER
POWER
GBIC
23
GBIC
24
CLASS 1
LASER PRODUCT
STATUS
TERMINAL
PORT
1
3
5
7
9
11
2
4
6
8
10
12
13
15
17
19
21
23R
14
16
18
20
22
24R
AT-9424T/GB
Gigabit Ethernet Switch
1
3
5
7
9
11
13
15
17
19
21
23R
2
4
6
8
10
12
14
16
18
20
22
24R
23
24
L/A
D/C
D/C
L/A
D/C
L/A
1000 LINK / ACT
HDX / COL
FDX
10/100 LINK / ACT
PORT ACTIVITY
L/A
1000 LINK / ACT
GBIC
Sales
VLAN
Production
VLAN
Untagged
Ports
Untagged
Ports