Nexus 1000v & STP

Answered Question
Apr 13th, 2010
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Does Nexus 1000 send BPDU to uplink port toward physical switch?


TIA


Ivan

Correct Answer by ryan.lambert about 7 years 1 month ago

Ivan,


No sir. Per the deployment guide:

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9902/guide_c07-556626.html



Loop Prevention

Another differentiating characteristic of the Cisco Nexus 1000V Series is that it does not run Spanning Tree Protocol. Although this might seem to be a significant departure from other Ethernet switches, potentially causing catastrophic network loops, in reality the Cisco Nexus 1000V Series implements a simple and effective loop-prevention strategy that does not require Spanning Tree Protocol.

Because the Cisco Nexus 1000V Series does not participate in Spanning Tree Protocol, it does not respond to Bridge Protocol Data Unit (BPDU) packets, nor does it generate them. BPDU packets that are received by Cisco Nexus 1000V Series Switches are dropped.

The Cisco Nexus 1000V Series uses a simple technique to prevent loops. Like a physical Ethernet switch, the Cisco Nexus 1000V Series performs source and destination MAC address lookups to make forwarding decisions. The VEM applies loop-prevention logic to every incoming packet on Ethernet interfaces. This logic is used to identify potential loops. Every ingress packet on a physical Ethernet interface is inspected to help ensure that the destination MAC address is internal to the VEM. If the destination MAC address is external, the Cisco Nexus 1000V Series will drop the packet preventing a loop back to the physical network.

Note: The Cisco Nexus 1000V Series prevents loops between the VEMs and the first-hop access switches without the use of Spanning Tree Protocol. However, this feature does not mean that Spanning Tree Protocol should be disabled on any access switches. Spanning Tree Protocol is still required by the access switches to prevent loops elsewhere in the physical topology.


HTH,

Ryan

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Correct Answer
ryan.lambert Tue, 04/20/2010 - 08:34
User Badges:

Ivan,


No sir. Per the deployment guide:

http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9902/guide_c07-556626.html



Loop Prevention

Another differentiating characteristic of the Cisco Nexus 1000V Series is that it does not run Spanning Tree Protocol. Although this might seem to be a significant departure from other Ethernet switches, potentially causing catastrophic network loops, in reality the Cisco Nexus 1000V Series implements a simple and effective loop-prevention strategy that does not require Spanning Tree Protocol.

Because the Cisco Nexus 1000V Series does not participate in Spanning Tree Protocol, it does not respond to Bridge Protocol Data Unit (BPDU) packets, nor does it generate them. BPDU packets that are received by Cisco Nexus 1000V Series Switches are dropped.

The Cisco Nexus 1000V Series uses a simple technique to prevent loops. Like a physical Ethernet switch, the Cisco Nexus 1000V Series performs source and destination MAC address lookups to make forwarding decisions. The VEM applies loop-prevention logic to every incoming packet on Ethernet interfaces. This logic is used to identify potential loops. Every ingress packet on a physical Ethernet interface is inspected to help ensure that the destination MAC address is internal to the VEM. If the destination MAC address is external, the Cisco Nexus 1000V Series will drop the packet preventing a loop back to the physical network.

Note: The Cisco Nexus 1000V Series prevents loops between the VEMs and the first-hop access switches without the use of Spanning Tree Protocol. However, this feature does not mean that Spanning Tree Protocol should be disabled on any access switches. Spanning Tree Protocol is still required by the access switches to prevent loops elsewhere in the physical topology.


HTH,

Ryan

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