Cisco IE 4000 Software Configuration Guide

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Configuring MSTP
Information About Configuring MSTP
Figure 43 Sequence of Events During Rapid Convergence
Bridge Protocol Data Unit Format and Processing
The RSTP BPDU format is the same as the IEEE 802.1D BPDU format except that the protocol version is set to 2. A new
1-byte Version 1 Length field is set to zero, which means that no version 1 protocol information is present. Table 3 shows
the RSTP flag fields.
The sending switch sets the proposal flag in the RSTP BPDU to propose itself as the designated switch on that LAN. The
port role in the proposal message is always set to the designated port.
The sending switch sets the agreement flag in the RSTP BPDU to accept the previous proposal. The port role in the
agreement message is always set to the root port.
2. Block
9. Forward
1. Proposal4. Agreement
6. Proposal
Root port
Designated port
8. Agreement 10. Agreement
Edge port
7. Proposal
5. Forward
3. Block
11. Forward
88761
Table 43 RSTP Flag Fields
Bit Function
0 Topology change (TC)
1Proposal
2–3:
00
01
10
11
Port role:
Unknown
Alternate port
Root port
Designated port
4 Learning
5Forwarding
6Agreement
7 Topology change acknowledgement (TCA)

Cisco IE 4000 Specifications

General

Product Type	Switch
Form Factor	DIN Rail Mountable
MAC Address Table Size	8000
Jumbo Frame Support	9216 bytes
Operating Temperature	-40°C to 70°C
Mean Time Between Failures (MTBF)	Over 500, 000 hours
Memory	256 MB DRAM
Mounting	DIN Rail, Wall
Certifications	EN 50121-4
Ports	8 x 10/100Base-TX Ethernet Ports