Title

The LAN access switch (discrete NE or module in a larger NE) is NOT capable of, or is NOT configured to; maintain the required VLAN separation for traffic originating from supported endpoints and DOES NOT route voice, VTC, PC communications client, and data traffic to their respective VLANs on the LAN. (Cat II impact)

Discussion

Some VVoIP hardware endpoints and hardware based VTC endpoints contain a multi-port Ethernet switch to provide a connection on the endpoint for external devices such as a workstation (i.e., PC port). This is done so that a PC and a workstation can share a single network cable drop and LAN access layer switch port. The PC port can, in general, support any device requiring an Ethernet connection. In theory, a VoIP phone, a desktop VTC unit could be daisy chained on a single LAN drop. These embedded multi-port Ethernet switches must be capable of maintaining the separation of the voice (VVoIP), data, VLANs as well as the VTC VLAN and PC Comm Client VLAN if present. For example the attached PC must not be able to directly access the phone’s or VTU’s configurations or communications traffic. VAN separation helps to prevent this. NOTE: the switch or endpoint will typically utilize 802.1Q trunking (VLAN tagging) but may use some other means to separate voice and data traffic. Typically when 802.1Q VLAN tagging is used, the phone firmware tags the VoIP packets while the embedded switch passes all packets without modification. This permits devices connected to the PC port to tag their packets and assign the proper VLAN to their traffic type. 802.1Q VLAN tagging enables the LAN to better maintain separation of the traffic and is therefore the preferred method. The LAN access switch (discrete NE or module in a larger NE) must be capable of, and must be configured to, support the VLAN separation method used by the supported endpoints. The NE may perform this function in various ways as determined by the overall VVoIP system and LAN design. However, the typical (or preferred) method used by an endpoint to maintain VLAN separation is 802.1Q VLAN tagging. As such, the LAN access port and NE needs to support the receipt of tagged packets and handle them appropriately to also maintain VLAN separation. While the NE may retag the packets thereby reassigning the VLAN based on some defined rule, the NE may not strip the tags and mix all traffic together. Furthermore, The LAN access NE supporting LAN cable drops will typically have a VLAN defined for each service (VVoIP, VTC, Data, PC Comm. Client) supported by the endpoints connected to the NE. Traffic within the respective VLANs may flow between different physical ports on the NE but may not change VLANs in the process. This must be done by a routing device (discrete NE or module in a larger NE) and must be controlled by an appropriate ACL. The LAN access layer Ethernet switch may be combined in the same unit with the routing device as in the case of a layer-3 switch or a router containing an Ethernet switch module.

Check Content

If the VVoIP or VTC endpoints supported by this NE provide a PC Port (has an embedded Ethernet switch), inspect the configurations of the NE to determine compliance with the following requirement: In the event the LAN access switch port supports a VVoIP or VTC endpoint with an embedded Ethernet switch, ensure the NE is capable of, and configured to, maintain the required VLAN separation from the endpoint and route voice, VTC, PC communications client, and data traffic to their respective VLANs on the LAN. NOTE: The NE may perform this function in various ways as determined by the overall VVoIP system and LAN design. However, the typical (or preferred) method used by an endpoint to maintain VLAN separation is 802.1Q VLAN tagging of the VVoIP traffic while letting PC port traffic pass unchanged. This permits both tagged and untagged traffic to come through the PC port. As such, the LAN access port and NE needs to support the receipt of tagged packets and handle them appropriately to also maintain VLAN separation. This may require the port be assigned to the data VLAN for the “default” traffic, while recognizing the VVoIP VLAN tag and then split the VVoIP traffic into its VLAN. While the NE may retag the packets thereby reassigning the VLAN based on some defined rule, the NE may not strip the tags and mix all traffic together. NOTE The LAN access layer Ethernet switch (discrete NE or module in a larger NE) supporting LAN cable drops will typically have a VLAN defined for each service (VVoIP, VTC, Data, PC Comm. Client) supported by the endpoints connected to the NE. Traffic within the respective VLANs may flow between different physical ports on the NE but may not change VLANs in the process. This must be done by a routing device (discrete NE or module in a larger NE) and must be controlled by an appropriate ACL. The LAN access layer Ethernet switch may be combined in the same unit with the routing device as in the case of a layer-3 switch or a router containing an Ethernet switch module.

Fix Text

In the event the LAN access switch port supports a VVoIP or VTC endpoint with an embedded Ethernet switch, ensure the NE is capable of, and configured to, maintain the required VLAN separation from the endpoint and route voice, VTC, PC communications client, and data traffic to their respective VLANs on the LAN. NOTE: The NE may perform this function in various ways as determined by the overall VVoIP system and LAN design. However, the typical (or preferred) method used by an endpoint to maintain VLAN separation is 802.1Q VLAN tagging. As such, the LAN access port and NE needs to support the receipt of tagged packets and handle them appropriately to also maintain VLAN separation. While the NE may retag the packets thereby reassigning the VLAN based on some defined rule, the NE may not strip the tags and mix all traffic together. NOTE: The LAN access layer Ethernet switch (discrete NE or module in a larger NE) supporting LAN cable drops will typically have a VLAN defined for each service (VVoIP, VTC, Data, PC Comm. Client) supported by the endpoints connected to the NE. Traffic within the respective VLANs may flow between different physical ports on the NE but may not change VLANs in the process. This must be done by a routing device (discrete NE or module in a larger NE) and must be controlled by an appropriate ACL. The LAN access layer Ethernet switch may be combined in the same unit with the routing device as in the case of a layer-3 switch or a router containing an Ethernet switch module.

Additional Identifiers

Rule ID: SV-21788r2_rule

Vulnerability ID: V-19647

Group Title: Deficient imp'n: LAN switch maint. VLAN sepa’t’n

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.