Cisco ME 3400 User Manual

15-12
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 15 Configuring MSTP
Understanding RSTP
Figure 15-5 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 one-byte Version 1 Length field is set to zero, which means that no version 1 protocol
information is present.
Table 15-3 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
Ta b l e 15-3 RSTP BPDU Flags
Bit Function
0 Topology change (TC)
1 Proposal
2–3:
00
01
10
11
Port role:
Unknown
Alternate port
Root port
Designated port
4 Learning
5 Forwarding
6 Agreement
7 Topology change acknowledgement (TCA)

Cisco ME 3400 Specifications

General

Category	Switch
Rack Mountable	Yes
Jumbo Frame Support	Yes
Authentication Method	RADIUS, TACACS+
RAM	128 MB
Flash Memory	32 MB
Power Device	Internal power supply
Model	ME 3400
Layer	Layer 2
MAC Address Table Size	8000 entries
Remote Management Protocol	SNMP, Telnet, SSH, HTTP, HTTPS
Features	VLAN support, IGMP snooping, Quality of Service (QoS)
Compliant Standards	IEEE 802.3, IEEE 802.3u, IEEE 802.1D, IEEE 802.1Q, IEEE 802.3ab, IEEE 802.3x
Memory	128 MB
Power Supply	AC 120/230 V (50/60 Hz)
Dimensions (H x W x D)	4.4 cm x 44.5 cm x 24.2 cm
Routing Protocol	Static routing