Cisco Systems N3KC3064TFAL3 Manual De Usuario
Extended System ID
A 12-bit extended system ID field is part of the bridge ID.
Figure 7: Bridge ID with Extended System ID
The switches always use the 12-bit extended system ID.
Combined with the bridge ID, the system ID extension functions as the unique identifier for a VLAN.
Table 6: Bridge Priority Value and Extended System ID with the Extended System ID Enabled
Extended System ID (Set Equal to the VLAN ID)
Bridge Priority Value
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 8
Bit 9
Bit
10
10
Bit
11
11
Bit
12
12
Bit
13
13
Bit
14
14
Bit
15
15
Bit
16
16
1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
STP MAC Address Allocation
Extended system ID and MAC address reduction is always enabled on the software.
Note
With MAC address reduction enabled on any switch, you should also enable MAC address reduction on all
other connected switches to avoid undesirable root bridge election and spanning tree topology issues.
other connected switches to avoid undesirable root bridge election and spanning tree topology issues.
When MAC address reduction is enabled, the root bridge priority becomes a multiple of 4096 plus the VLAN
ID. You can only specify a switch bridge ID (used by the spanning tree algorithm to determine the identity
of the root bridge, the lowest being preferred) as a multiple of 4096. Only the following values are possible:
ID. You can only specify a switch bridge ID (used by the spanning tree algorithm to determine the identity
of the root bridge, the lowest being preferred) as a multiple of 4096. Only the following values are possible:
• 0
• 4096
• 8192
• 12288
• 16384
• 20480
• 24576
• 28672
• 32768
Cisco Nexus 3000 NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)U3(1)
OL-26590-01
65
Configuring Rapid PVST+
Understanding STP