ECP-206 Exam Dumps : Ericsson Certified Associate - IP Networking

The purpose of the RT attribute is to identify the destination VPN on the egress PE. RT stands for route target, which is a BGP extended community attribute that is used in MPLS VPNs. RT is attached to VPN routes by the ingress PE router and is used to control the import and export of routes between different VPNs. The egress PE router uses the RT value to determine which VPN routes belong to which VPN customers and installs them in the appropriate VRF table56.

References: IP Routing: BGP Configuration Guide - BGP-RT and VPN … - Cisco, : The Ruby Text element - MDN Web Docs

There are 8 different priorities available to use in a VLAN header. A VLAN header is a 4-byte field that is inserted into an Ethernet frame to indicate the VLAN membership and priority of the frame. The VLAN header consists of two subfields: the tag protocol identifier (TPID) and the tag control information (TCI). The TCI subfield contains three subfields: the priority code point (PCP), the drop eligible indicator (DEI), and the VLAN identifier (VID). The PCP subfield is a 3-bit field that specifies the priority level of the frame, ranging from 0 (lowest) to 7 (highest). The PCP values can be used to implement quality of service (QoS) mechanisms on bridges and switches12.

References: HTML rt Tag - W3Schools, VLAN 0 Priority Tagging Support - Cisco

In an Ethernet frame carrying a VLAN tag, the VLAN tag appears before the type field. A VLAN tag is a 4-byte field that is inserted into an Ethernet frame to indicate the VLAN membership and priority of the frame. The VLAN tag consists of two subfields: the tag protocol identifier (TPID) and the tag control information (TCI). The TPID subfield is a 16-bit field that identifies the frame as an IEEE 802.1Q-tagged frame, with a value of 0x8100. The TCI subfield is a 16-bit field that contains the priority code point (PCP), the drop eligible indicator (DEI), and the VLAN identifier (VID). The VLAN tag appears between the source MAC address and the type fields of the original frame, shifting the type field by four bytes. The type field indicates the type of the payload, such as IP or ARP .

References: [IEEE 802.1Q - Wikipedia], [VLAN Tagging Explained with DTP Protocol - GeeksforGeeks]