Overview: Link Aggregation Control Protocol (LACP) is another option when configuring EtherChannels Study Notes: LACP is an open protocol adhering to the 802.3ad standard It uses the multicast address of 01-80-c2-00-00-02 Channel mode must be set to “active” or “passive” to specify an LACP port-channel Active – Enable LACP unconditionally Passive – Enable LACP […]
Overview: Port Aggregation Protocol (PAgP) is another option when configuring EtherChannels Study Notes: PAgP is a Cisco proprietary protocol It uses the multicast address of 01-00-0C-CC-CC-CC Channel mode must be set to “auto” or “desirable” to specify a PAgP port-channel Auto – Enable PAgP only if a PAgP device is detected Desirable – Enable PAgP […]
Overview: Static port-channels are an option when configuring EtherChannels Study Notes: No protocol is applied (not LACP or PAgP) Channel mode must be “On” to specify a static port-channel Maximum number of links in port-channel is 8 It is recommended to configure number of links as 1, 2, 4 or 8 Statically configured port-channels […]
Overview: Link Layer Discovery Protocol LLDP is similar to CDP in that it supports non-Cisco devices Study Notes: Link Layer Discovery Protocol (LLDP): Link Layer Discovery Protocol (LLDP) is a device discovery protocol that runs over Layer 2 (the data link layer) on many devices (routers, bridges, access servers, and switches) LLDP allows network […]
Overview: Cisco Discovery Protocol CDP is a Cisco proprietary layer 2 protocol to help switches learn about neighboring switches Study Notes: Cisco Discovery Protocol (CDP) Cisco Discovery Protocol is a Layer 2, media-independent, and network-independent protocol that networking applications use to learn about nearby, directly connected devices Cisco Discovery Protocol is enabled by default […]
Overview: BPDUGuard protects against loops that STP can’t protect against when PortFast is enabled Study Notes: BPDU Guard complements the functionality of PortFast On PortFast-enabled ports, BPDU Guard provides the protection against Layer 2 loops that STP cannot provide when STP PortFast is enabled In a valid configuration, PortFast Layer 2 LAN interfaces (edge ports) […]
Overview: PortFast is a Spanning-Tree option that causes a port to immediately come up without going through initial STP learning and listening phases Study Notes: STP PortFast causes a Layer 2 LAN port configured as an access port to enter the forwarding state immediately, bypassing the listening and learning states You can use PortFast on […]
Overview: Per-VLAN Spanning-Tree plus and Rapid PVST+ are enhancements to 802.1D STP Study Notes: 802.1D Spanning Tree Protocol (STP) has a drawback of slow convergence Cisco Catalyst switches support three types of STPs, which are PVST+, rapid-PVST+ and MST. Per-VLAN Spanning-Tree plus (PVST+) PVST+ is based on IEEE802.1D standard and includes Cisco proprietary extensions such […]
Overview: The Native VLAN is used to pass untagged traffic (non-vlan associated) to a neighboring switch Study Notes: Native VLAN: On a trunk link, each frame must be distinguishable as being within exactly one VLAN If a frame does not carry an 802.1Q VLAN tag, it is considered to be in the Native VLAN […]
Overview: 802.1Q is the standard used for switches to communicate Layer 2 VLAN information between each other Study Notes: 802.1Q 802.1Q, or dot1q for short, is a way to tag vlans on an Ethernet frame It is an open standard and more popularly used than Cisco’s proprietary VLAN encapsulation protocol called Inter-Switch Link (ISL) […]