Request For Proposal (RFP) A request for proposal

Spanning Tree Protocol (STP) STP runs on bridges and switches that are 802.1D-compliant. There are different flavors of STP, but 802.1D is the most popular and widely implemented. You implement STP on bridges and switches in order to prevent loops in the network. Use STP in situations where you want redundant links, but not loops. Redundant links are as important as backups in the case of a failover in a network. A failure of your primary activates the backup links so that users can continue to use the network. Without STP on the bridges and switches, such a failure can result in a loop. If two connected switches run different flavors of STP, they require different timings to converge. When different flavors are used in the switches, it creates timing issues between Blocking and Forwarding states. Therefore, it is recommended to use the same flavors of STP.<br>

Spanning Tree Protocol (STP)<br>

Rapid Spanning Tree Protocol (RSTP) Rapid Spanning Tree Protocol (RSTP; IEEE 802.1w) can be seen as an evolution of the 802.1D standard more than a revolution. The 802.1D terminology remains primarily the same. Most parameters have been left unchanged so users familiar with 802.1D can rapidly configure the new protocol comfortably. In most cases, RSTP performs better than proprietary extensions of Cisco without any additional configuration. 802.1w can also revert back to 802.1D in order to interoperate with legacy bridges on a per-port basis. This drops the benefits it introduces.<br>

Rapid Spanning Tree Protocol (RSTP) RSTP (IEEE 802.1w) natively includes most of the Cisco proprietary enhancements to the 802.1D spanning tree, such as BackboneFast, UplinkFast, and PortFast. RSTP can achieve much faster convergence in a properly configured network, sometimes in the order of a few hundred milliseconds. Classic 802.1D timers, such as forward delay and max_age, are only used as a backup and should not be necessary if point-to-point links and edge ports are properly identified and set by the administrator. Also, the timers should not be necessary if there is no interaction with legacy bridges.<br>

BPDU Cisco Feature There are rules to describe one way of determining what spanning tree will be computed by the algorithm, but the rules as written require knowledge of the entire network. The bridges have to determine the root bridge and compute the port roles (root, designated, or blocked) with only the information that they have. To ensure that each bridge has enough information, the bridges use special data frames called Bridge Protocol Data Units (BPDUs) to exchange information about bridge IDs and root path costs.<br>

BPDU Cisco Feature A bridge sends a BPDU frame using the unique MAC address of the port itself as a source address, and a destination address of the STP multicast address 01:80:C2:00:00:00.
There are three types of BPDUs:

Configuration BPDU (CBPDU), used for Spanning Tree computation
Topology Change Notification (TCN) BPDU, used to announce changes in the network topology
Topology Change Notification Acknowledgment (TCA)

BPDUs are exchanged regularly (every 2 seconds by default) and enable switches to keep track of network changes and to start and stop forwarding at ports as required.<br>

UplinkFast Cisco Feature UplinkFast
Another form of immediate transition to the forwarding state included in RSTP is similar to the Cisco UplinkFast proprietary spanning tree extension. Basically, when a bridge loses its root port, it is able to put its best alternate port directly into the forwarding mode (the appearance of a new root port is also handled by RSTP). The selection of an alternate port as the new root port generates a topology change. The 802.1w topology change mechanism clears the appropriate entries in the Content Addressable Memory (CAM) tables of the upstream bridge. This removes the need for the dummy multicast generation process of UplinkFast.

UplinkFast does not need to be configured further because the mechanism is included natively and enabled in RSTP automatically.<br>

Edge Port Cisco Feature Edge Ports

The edge port concept is already well known to Cisco spanning tree users, as it basically corresponds to the PortFast feature. All ports directly connected to end stations cannot create bridging loops in the network. Therefore, the edge port directly transitions to the forwarding state, and skips the listening and learning stages. Neither edge ports or PortFast enabled ports generate topology changes when the link toggles. An edge port that receives a BPDU immediately loses edge port status and becomes a normal spanning tree port. At this point, there is a user-configured value and an operational value for the edge port state. The Cisco implementation maintains that the PortFast keyword be used for edge port configuration. This makes the transition to RSTP simpler.<br>

Root Port The role is now a variable assigned to a given port.<br>

IEEE 802.1 Standards The port that receives the best BPDU on a bridge is the root port. This is the port that is the closest to the root bridge in terms of path cost. The STA elects a single root bridge in the whole bridged network (per-VLAN). The root bridge sends BPDUs that are more useful than the ones any other bridge sends. The root bridge is the only bridge in the network that does not have a root port. All other bridges receive BPDUs on at least one port.<br>

IEEE 802.1 Standards The STP (802.1D) defines five different port states:

Disabled
Listening
Learning
Blocking
Forwarding

The RSTP (802.1w) port states are:

Discarding
Learning
Forwarding<br>

Network Address Translation (NAT) NAT allows an Internet Protocol (IP) network to maintain public IP addresses separately from private IP addresses. NAT is a popular technology for Internet connection sharing. It is also sometimes used in server load balancing applications on corporate networks.
In it's most common configuration, NAT maps all of the private IP addresses on a home network to the single IP address supplied by an Internet Service Provider (ISP). This allows computers on the home LAN to share a single Internet connection. Additionally, it enhances home network security by limiting the access of external computers into the home IP network<br>

NAT Overload PAT configuration is many to one.<br>

NAT Static NAT is the simplest form of NAT, one to one.<br>

Transparent Bridge The spanning-tree calculation occurs when the bridge is powered up and whenever a topology change is detected. The calculation requires communication between the spanning-tree bridges, which is accomplished through configuration messages (sometimes called bridge protocol data units, or BPDUs). Configuration messages contain information identifying the bridge that is presumed to be the root (root identifier) and the distance from the sending bridge to the root bridge (root path cost). Configuration messages also contain the bridge and port identifier of the sending bridge, as well as the age of information contained in the configuration message.<br>

Transparent Bridge Bridges exchange configuration messages at regular intervals (typically one to four seconds). If a bridge fails (causing a topology change), neighboring bridges will detect the lack of configuration messages and initiate a spanning-tree recalculation.<br>

Transparent Bridge<br>

Border Gateway Protocol (BGP) BGP Revealed
BGP basically determines how an Autonomous System (AS), or independent network, passes packets of data to and from another AS. Rather than depend on a calculated metric to determine the best path, BGP uses attribute information that is included in route advertisements to determine the chosen path.<br>

Border Gateway Protocol (BGP) ASBGP<br>

Autonomous System (AS) Within the Internet, an Autonomous System (AS) is a collection of connected Internet Protocol (IP) routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the Internet.
Interior routing protocols:
packetlife.net/posters/ISO_Interior_Routing_Protocol.pdf<br>

Root Bridge<br>

Root Bridge<br>

Root Bridge<br>

Root Bridge<br>

Root Bridge<br>

Root Bridge<br>