CCIE EI v1.1 - Layer 2 Technologies

CDP uses type-length-value fields to advertise neighbor details such as device name, port ID, version, and duplex; view this data with show CDP neighbor detail.

Udld detects unidirectional links to prevent loops by echoing switch IDs across fiber or copper ports, signaling bidirectional status to trigger aggressive error-disabled shutdown when needed.

Access ports are edge ports that carry a single vlan, used by desktops, printers, and access points. Configure them statically as access ports and disable DTP to prevent unauthorized trunking.

Understand VLAN concepts and how VLAN databases, trunks, and SVIs enable scalable layer two networks, inter-VLAN routing, and broadcast domain segmentation across switches.

Explain VTP versions 1 and 2, their server, client, transparent, and off modes, MD5 password hashing, domain name and revision, and VLAN range rules for consistent reachability.

Explore vtp version 3 features, including extended vlan support and an enhanced server mode with a single primary server, plus using http to advertise mst configurations across a network.

Explore how VTP pruning reduces broadcast traffic by automatically pruning unused VLANs on trunk links, with VTP pruning version 3 requiring per-switch enablement and configuration.

Learn to distinguish manual pruning from VP pruning and configure explicit VLAN allow lists on trunk interfaces to control which VLANs propagate between switches.

Learn how 802.1Q trunk ports tag multiple VLANs across switches, use a native VLAN for untagged frames, and implement pruning and encapsulation to scale VLAN traffic.

Learn how ether channels and port channels create a single logical link by grouping two physical links, with protocol options like lacp and pagp and the need for consistent configurations.

Learn how ether channel guard detects misconfigurations between port channels using spanning tree views of the logical interface and places misconfigured links into an error-disabled state.

Learn how etherchannel load sharing across two links uses a flow-based hash to distribute traffic, not per packet. Discover how source-destination IP hashing and link count influence balance and performance.

Explore Cisco's PAgP port aggregation protocol for creating ether channels. Learn auto and desirable modes, hello exchanges, and the implications of aggregation versus physical learn methods for reliable configuration.

Learn lacp, the open 802.3ad standard for building ether channels across non-Cisco gear. Master active and passive modes, port and system priorities, max bundle, and fast switchover.

Explore spanning tree protocol concepts and Cisco implementations (pvst and pvst+, rapid pvst, mst); learn root bridge, root port, bpdu, and bridge ID to prevent layer 2 loops.

Explore PVST+ and the extended system ID for VLAN-specific spanning trees. Learn how root bridges, root ports, BPDU types, and port roles govern blocking and forwarding.

Learn how rapid pvst+ spanning tree speeds convergence by using root, designated, backup, and alternate ports, edge ports, and point-to-point or shared links, and synchronizing BPDU information.

Explore 802.1s mst, the multiple instance spanning tree, and how it groups vlan mappings into regions to reduce convergence. Understand regions, instances, and the default domain name in mst configuration.

Learn to designate the root bridge for specific VLAN ranges using PVST, Rapid PVST, and MST. Explore per-VLAN and region-based priorities, root primary/secondary, and 4096 increments.

Explore port priority in spanning tree by manipulating switch three as the root bridge to influence a neighbor’s root port and blocking port, using per‑VLAN priority increments in rapid pvst.

Learn how to influence local spanning-tree decisions by adjusting per-interface costs in pvst and mst, using ethernet ports, root and blocking roles, and port channels.

Learn how spanning tree timers: hello time, max age, and forward delay, are configured and adjusted directly, indirectly, or by the diameter macro to improve convergence across VLANs and MST.

Portfast speeds user sign-ins by bypassing listening and learning in spanning tree, with edge and network port modes, trunk considerations, and bridge assurance to prevent loops.

Enable bpdu guard on edge ports to terminate the stp domain and auto-disable a port when a bpdu is received. Apply globally or per port to protect desktops and printers.

BPDU filter lets traffic pass but filters out BPDUs, preventing port shutdown. Configure per interface or globally, understand its interaction with portfast and BPDU guard to avoid spanning-tree loops.

Learn how root guard prevents another switch from becoming the root bridge by blocking ports receiving superior bpdus on designated forwarding ports, keeping the root stable.

Explore span and rspan traffic mirroring on switches for local and remote span capture, and learn to configure span sessions by selecting source and destination.

Learn IGMP across versions 1 through 3, including the IGMP querier, membership reports, joins and leaves, and how PIM sparse mode and source-specific multicast optimize layer 2/3 multicast.

Learn how igmp snooping lets a switch inspect membership reports for multicast groups within a vlan, enabling precise forwarding decisions and support for igmp version 3 source-specific multicast.

Explains the point-to-point protocol (ppp) and hdlc encapsulation for serial links. Shows how link control protocol (lcp) handles authentication (pap and chap), multi-link support, and ipcp negotiation for default routing.

Learn pap authentication, a password authentication protocol used with pptp that sends username and password in clear text, and see how to enable it on routers and the interface.

Explain CHAP authentication, a three-way handshake where the authenticator challenges the peer and verifies an MD5 hash of the username and password; configure PPTP, host name, and password to succeed.

Explore how PPPoE encapsulates PPP packets in Ethernet to provide point-to-point protocol features over Ethernet, including active discovery, CHAP authentication, dialer pools, and virtual templates with broadband access group.