Networking Chapter 7

Ideal design for BB

- A mixture of layer-2 and layer-3 Ethernet switches - Access Layer • 100Base-T Later 2 switches with cat5e or cat6 - Distribution Layer • 100base-T or 1000BaseT/F Layer 3 switches - Core Layer • Layer 3 switches running 10GbE or 40GbE over fiber

Router Compared to a Switch

- Performs more processing -Processes only messages specifically addressed to it - Recognizes that message is specifically addressed to it before message is passed to network layer for processing - Builds new data link layer packet for transmitted packets.

Disadvantage of VLAN

Cost - Management complexity - Some "bleeding edge" technology issues to consider

Modules

Each module is a certain type of network device. One module might be a 16port 100Base T switch, another might be a router, where another might be a 4port 1000 base F switch.

FEC

Forwarding Equivalence Classes - defined by the network manager. Each FEC has a reserved data rate and a QoS.

What IEEE standard governs VLANS

IEEE802.1q

MDF/ CDF

Main distribution facility - room containing the rack of equipment.

Switch

Switches connect more than 2 LAN segments that use the same data link and network protocol. They maybe connect the same or different types of cable. Switches typically provide ports for 4,8,16, 32 separate LAN segments and most enable all ports to be in use simultaneously so they are faster than bridges.

Core Layer

The central part of a network that provides access to the distribution layer. Often a very fast BN that runs through the center of a campus or office complex.

VLAN Tag

When a VLAN switch receives an Ethernet frame that needs to go to a computer on another VLAN switch it changes the Ethernet frame by inserting the VLAN ID umber and a priority code into the VLAN rage field.

LSRs

With Multi protocol label switching routers called Label switched routers are used.

Gateway

a device that connects 2 dis-similar networks, allows networks of different vendors to communicate by translating one vendor's protocol into another.

VLAN Trunks

circuits that connect two VLAN switches and enables traffic to flow from one switch to another.

Enterprise Network

may be called a backbone network is if connects all networks within a company regardless of whether it crosses state, national or international boundaries.

Multiswitch VLAN

several switches are used to build the VLANs

Access Layer

the layer that connects clients or servers to the rest of the network. often a LAN

Distribution Layer

the part of a network that connects the access layer to other access layers and to the core layer. Often a BN in a building.

Advantage of VLAN

ability to manage the flow of traffic on the LAN and backbone very precisely. VLANs often provide faster performance than the other backbone architecture. Ability to prioritize traffic. The VLAN tags information included in the Ethernet packet defines the VLAN to which the packet belongs and also specifies a priority code based on the IEEE standard.

How switched backbones work?

Uses one device, usually a layer 2 switch, to connect the LANs. It is a star topology with one switch at its center.

Backbone Network

A high speed network that connects many networks, typically uses higher speed circuits to interconnect a series of LANs and provide connection to other BNs, MANs, WANs and internet.

Difference between a router and a switch

A router Perform more processing on each message than a switch therefore operating slower. A rougher processes only those messages that are specifically addressed to it.

What are the three technology layers important in backbone design?

Access Layer Distribution Layer Core Layer

Best Practice Backbone Design

Best practice backbone architecture for most organizations is a switched backbone (using rack or chassis switch) or VLAN in the distribution layer and a routed backbone in the core layer. Recommended technology is gigabit Ethernet.

Improving BN performance

Choosing the best network layer routing protocols. Upgrading the faster circuits and adding additional circuits on very busy backbones. One can move servers closer to the end users or reduce broadcast traffic to reduce backbone traffic.

How do VLANs work?

Each computer is assigned into a VLAN that has a VLAN ID Each VLAN ID is matched to a traditional IP subnet Each computer gets an IP address from that switch Similar to how DHCP operates Computers are assigned into the VLAN based on physical port they are plugged into

Chassis Switch

Enables users to plug modules directly into the switch.

Layer 2 switches vs. Layer 3

Layer 2 Switches use the data link layer address to forward packets between network segments. Layer 3 switches - same as Layer 2 but they switch messages on the basis of their network layer address. These switches provide the best of both switches and routers, they can be used in place of routers but provide the benefits of traditional layer 2 switches; much faster transmission and more simultaneously active ports and routers.

MPLS

Multiprotocol Label Switching- an approach to improving QoS and the movement of packets with different layer 2 protocols through TCP/IP networks.

Advantage of Switched/ Routed Backbones

SWITCHED- Rack of equipment places all network equipment in one place for easy maintenance and upgrade. It becomes simple to move computers from one LAN. Chassis switch is sometimes used instead of Rack, their flexibility is a key advantage, it becomes simple to add new modules with additional ports as the LAN grows. -Improved performance (200-600% higher) due to simultaneous access of switched operations - A simpler more easily managed network - less devices. ROUTED- it clearly segments each part of the network connected to the backbone. Easier to manage, LANs are separate entities, segments - Each message stays in one LAN; unless addressed outside the LAN - Easier to manage, LANs are separate entities, segments

Disadvantage of Switched/ Routed

SWITCHED- With rack of equipment it can cause problems if many of the computers on the switch are high traffic computers. An area may become a bottleneck. ROUTED - routers in the networks can sometimes be slower. Routers are more expensive and require more management than switches. - Tend to impose time delays - Require more management than switches

How routed backbones work? Where is it commonly used?

Uses a set of routers or layer3 switches to connect LANs together and moves messages using layer 3 addresses. Sometimes called subnetted backbones or hierarchal backbones and are most commonly used to connect different buildings within the same campus network.

Router

a device that connects two similar networks having the same network protocol. It also chooses the best route btw 2 networks when there are multiple paths btw them.

Single switch VLAN

means that the VLAN operates only inside one switch. The computers on the VLAN are connected into the one switch and assigned by software into different VLANs

VLAN ID

ranges from 1 to 1005 or to 4094 depending on whether the extended range standard is used. Each VLAN ID is matched to a traditional IP subnet, so each computer connected to a VLAN switch also receives a traditional IP address by the VLAN switch.