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BigIron RX Series Configuration Guide
349
53-1002253-01
SuperSpan™
12
Each Brocade device that is configured for SuperSpan forwards the BPDU using the changed
destination MAC address. At the other end of the tunnel, the Brocade device connected to the
customer's network changes the destination MAC address back to the bridge group address
(01-80-c2-00-00-00).
Preforwarding state
To ensure that the customer's network has time to converge at Layer 2 and prevent loops, the
Brocade devices configured for SuperSpan use a special forwarding state, Preforwarding. The
Preforwarding state occurs between the Learning and Forwarding states and by default lasts for
five seconds. During the Preforwarding state, the Brocade device forwards tunneled BPDUs from
customers only and does not forward data traffic. This ensures that the customer’s network will
detect the Layer 2 loop and block a port. The SP network remains unblocked. After the
Preforwarding state, the Brocade ports change to the Forwarding state and forward data traffic as
well as BPDUs.
The default length of the Preforwarding state is five seconds. You can change the length of the
Preforwarding state to a value from 3 – 30 seconds.
Figure 35
shows an example of how the Preforwarding state is used.
FIGURE 35
SuperSpan preforwarding state
In this example, a customer has two links to the SP. Since the SP is running SuperSpan, the SP
ports enter the Preforwarding state briefly to allow the customer ports connected to the SP to
detect the Layer 2 loop and block one of the ports.
NOTE
If you add a new device to a network that is already running SuperSpan, you must enable SuperSpan
on the new device, at least on the VLANs that will be tunneling the customer traffic. Otherwise, the
new device does not use the Preforwarding state. This can cause temporary loops in the network.
During Preforwarding state, SP
forwards all tunneled customer
BPDUs, allowing customer time
to detect the loop and block a port.
Cust 1
FWD
BLK
BPDU
Preforwarding
Tunneled BPDU
SP 1
SP 2
SuperSpan
root bridge
BPDU
Preforwarding
Содержание BigIron RX Series
Страница 100: ...24 BigIron RX Series Configuration Guide 53 1002253 01 Logging on through the Web Management Interface 2 ...
Страница 192: ...116 BigIron RX Series Configuration Guide 53 1002253 01 Configuring authentication method lists 4 ...
Страница 228: ...152 BigIron RX Series Configuration Guide 53 1002253 01 Enabling WAN PHY mode support 6 ...
Страница 312: ...236 BigIron RX Series Configuration Guide 53 1002253 01 Displaying IP information 7 ...
Страница 356: ...280 BigIron RX Series Configuration Guide 53 1002253 01 Resetting LLDP statistics 9 ...
Страница 402: ...326 BigIron RX Series Configuration Guide 53 1002253 01 Transparent firewall mode 11 ...
Страница 432: ...356 BigIron RX Series Configuration Guide 53 1002253 01 SuperSpan 12 ...
Страница 500: ...424 BigIron RX Series Configuration Guide 53 1002253 01 MRP CLI example 14 ...
Страница 580: ...504 BigIron RX Series Configuration Guide 53 1002253 01 Configuring multicast traffic engineering 18 ...
Страница 591: ...BigIron RX Series Configuration Guide 515 53 1002253 01 Displaying traffic reduction 19 ...
Страница 592: ...516 BigIron RX Series Configuration Guide 53 1002253 01 Displaying traffic reduction 19 ...
Страница 598: ...522 BigIron RX Series Configuration Guide 53 1002253 01 Viewing Layer 2 ACLs 20 ...
Страница 656: ...580 BigIron RX Series Configuration Guide 53 1002253 01 Trunk formation 22 ...
Страница 754: ...678 BigIron RX Series Configuration Guide 53 1002253 01 Displaying RIP filters 24 ...
Страница 814: ...738 BigIron RX Series Configuration Guide 53 1002253 01 Displaying OSPF information 25 ...
Страница 932: ...856 BigIron RX Series Configuration Guide 53 1002253 01 Generalized TTL security mechanism support 26 ...
Страница 980: ...904 BigIron RX Series Configuration Guide 53 1002253 01 Clearing IS IS information 28 ...
Страница 1000: ...924 BigIron RX Series Configuration Guide 53 1002253 01 Using secure copy 30 ...
Страница 1088: ...1012 BigIron RX Series Configuration Guide 53 1002253 01 IP source guard 35 ...
Страница 1108: ...1032 BigIron RX Series Configuration Guide 53 1002253 01 Reading CDP packets 37 ...
Страница 1126: ...1050 BigIron RX Series Configuration Guide 53 1002253 01 Clearing sFlow statistics 39 ...
Страница 1140: ...1064 BigIron RX Series Configuration Guide 53 1002253 01 802 1s Multiple Spanning Tree Protocol 40 ...
Страница 1324: ...1248 BigIron RX Series Configuration Guide 53 1002253 01 Displaying OSPFv3 information 48 ...
Страница 1363: ...BigIron RX Series Configuration Guide 1287 53 1002253 01 Continuous System Monitor 51 ...
Страница 1364: ...1288 BigIron RX Series Configuration Guide 53 1002253 01 Continuous System Monitor 51 ...
Страница 1404: ...1328 BigIron RX Series Configuration Guide 53 1002253 01 Commands That Require a Reload D ...
Страница 1458: ...1382 BigIron RX Series Configuration Guide 53 1002253 01 VSRP E ...