Which two link protocols are used to carry multiple VLANs over a single link? (Choose two.)
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The two standards for carrying tagged VLAN traffic across single (trunk) links are 802.1q and ISL.
The two link protocols used to carry multiple VLANs over a single link are 802.1q and ISL.
802.1q is a standard protocol for VLAN tagging in Ethernet networks. It adds a VLAN tag to the Ethernet frame, which carries information about the VLAN ID. This allows multiple VLANs to be carried over a single physical link, and the VLANs can be separated and identified by their unique VLAN ID.
ISL, or Inter-Switch Link, is a proprietary protocol developed by Cisco. Like 802.1q, it adds a VLAN tag to the Ethernet frame to carry VLAN information. However, ISL can carry other information as well, such as Quality of Service (QoS) and Spanning Tree Protocol (STP) information. ISL is used primarily in Cisco networks and is not supported by other vendors.
VTP, or VLAN Trunking Protocol, is a Cisco proprietary protocol used to manage VLANs across a network. It is not a link protocol for carrying multiple VLANs over a single link.
IGP, or Interior Gateway Protocol, is a protocol used by routers to exchange routing information within an autonomous system. It is not a link protocol for carrying multiple VLANs over a single link.
802.3u is a standard for Fast Ethernet, which operates at 100 Mbps. It is not a link protocol for carrying multiple VLANs over a single link.