Connecting Cisco Devices to Non-Cisco 802.1Q Cloud

ABC.

When connecting Cisco devices to a non- Cisco 802.1Q cloud, several considerations must be taken into account. Here are the correct statements about connecting Cisco devices to a non- Cisco 802.1Q cloud:

A. Because Cisco devices transmit BPDUs to the SSTP multicast MAC address on VLANs other than the native VLAN of the trunk, non- Cisco devices do not recognize these frames as BPDUs and flood them on all ports in the corresponding VLAN.

Explanation: Cisco switches send BPDU frames using the SSTP (Shared Spanning Tree Protocol) multicast MAC address, which is different from the IEEE 802.1D BPDU multicast MAC address used by non- Cisco switches. As a result, non- Cisco devices do not understand these frames and broadcast them on all ports in the corresponding VLAN, leading to broadcast storms.

B. Cisco devices connected to the non- Cisco 802.1Q cloud receive these flooded BPDUs. This BPDU reception allows Cisco switches to maintain a per-VLAN spanning tree topology across a cloud of non- Cisco 802.1Q devices.

Explanation: Cisco devices connected to the non- Cisco 802.1Q cloud will receive the flooded BPDUs. The reception of these frames enables the Cisco switches to build and maintain a per-VLAN spanning tree topology across the non- Cisco 802.1Q cloud.

D. Because Cisco devices transmit BPDUs using the industry standard IEEE 802.1D spanning tree multicast MAC address (01-80-C2-00-00-00), the non- Cisco 802.1Q cloud will seamlessly participate in spanning tree protocol.

Explanation: Cisco devices transmit BPDUs using the industry standard IEEE 802.1D BPDU multicast MAC address, which is the same address used by non- Cisco devices. Therefore, the non- Cisco 802.1Q cloud can participate seamlessly in spanning tree protocol, and both Cisco and non- Cisco devices can use the same spanning tree protocol instance.

C, E, and F are incorrect statements:

C. The non- Cisco 802.1Q cloud that separates the Cisco devices is treated as a single broadcast segment between all devices connected to the non- Cisco 802.1Q cloud through 802.1Q trunks.

Explanation: This statement is incorrect. The non- Cisco 802.1Q cloud should be treated as multiple broadcast segments, each separated by an 802.1Q trunk. Each VLAN in the non- Cisco 802.1Q cloud is a separate broadcast domain, and broadcast traffic should not be forwarded between them.

E. Only layer 3 connections will work between Cisco devices and non- Cisco 802.1Q cloud.

Explanation: This statement is incorrect. Layer 2 connections can also work between Cisco devices and non- Cisco 802.1Q cloud, provided that the appropriate configuration is made, and the limitations of the non- Cisco devices are taken into account.

F. Additional equipment will be needed to transmit traffic between Cisco devices and non- Cisco 802.1Q cloud direct connectivity is not possible.

Explanation: This statement is incorrect. Direct connectivity between Cisco devices and non- Cisco 802.1Q cloud is possible, but the appropriate configuration is needed to avoid issues such as VLAN mismatch, native VLAN mismatch, and broadcast storm.