Overview: Frame rewrite is a crucial step in routing a packet through a router. Frame rewrite is determining how to construct the Layer 2 frame header to allow the packet to be properly encapsulated toward its next hop and forward the packet out the correct interface. Study Notes: Here is the process: Packet arrives […]
Overview: Routers have many different routes in their tables, but need to have a fast way (forwarding decision) to find the best path to a destination network. Study Notes: A prefix is a network address and a route mask Typically, the forwarding decision in a router is based on three processes – Routing protocols, […]
Overview: Understand how a packet is handled by different devices along a path in a network. In this scenario, the sender is PC1 and the receiver is PC2. Study Notes: PC1 creates a packet with the destination IP address of PC2 PC1 determines that PC2’s IP address is on a different network PC1 looks up […]
Overview: Routing concepts describe the way a packet transits a network from source host to destination host. Layer 2 and Layer 3 protocols are required to receive the packet, deencapsulate it, determine the destination, determine the exit interface, encapsulate it and transmit it. The following are the routing concepts covered in the CCNA: Study Notes: […]
Overview: A switch stack is a set of up to nine Cisco EtherSwitch service modules or Catalyst 3750 switches connected through their Cisco StackWise ports. One of the Cisco EtherSwitch service modules or Catalyst 3750 switches controls the operation of the stack and is called the stack master. It is typically used in the access […]
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: EtherChannel is a way of combining multiple ports into a single one. Layer 2 EtherChannel combines multiple physical switchports whereas Layer 3 EtherChannel combines multiple logical interfaces such as subinterfaces. Study Notes: There are 3 options when configuring Port-Channels: 2.9.a Static PortChannel 2.9.b Port Aggregation Protocol (PaGP) 2.9.c Link Aggregation Protocol (LACP) The […]
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 […]