1. Local Area Networks: Internetworking
Chapter 8
Local Area Networks: Internetworking

2. Topics Reasons for interconnecting
Identify the functions and purpose of
Bridge
Hub
Switch
Router

3. Why Interconnect?
To separate / connect one corporate division with another.
To connect two LANs with different protocols.
To connect a LAN to the Internet.
To break a LAN into segments to relieve traffic congestion.
To provide a security wall between two different types of users.

4. Bridges
A device that interconnects two LANs that both have MAC sublayer
Connect two CSMA/CD LANs
Connect one CSMA/CD LAN with another Token Ring LAN
Basic functions

5. Connecting two LANs of different types

6. Connecting two same-type LANs

7. Transparent Bridge
Observes all traffic and builds routing tables from this observation – so-called
Each bridge has two connections (ports) and there is a routing table associated with each port.
A bridge observes each frame that arrives at a port, extracts the source address from the frame, and places that address in the port’s routing table.
A transparent bridge is found with CSMA/CD LANs

9. Transparent Bridge
A transparent bridge can also convert one frame format to another --- called gateway
The bridge removes the headers and trailers from one frame format and inserts (encapsulates) the headers and trailers for the second frame format.

11. Source-routing Bridge
A source-routing bridge is found with token ring networks.
Source-routing bridges do not learn from watching tables.
When a workstation wants to send a frame, it must know the exact path of network / bridge / network / bridge / network …
If a workstation does not know the exact path, it sends out a discovery frame.
The discovery frame makes its way to the final destination, then as it returns, it records the path.

13. Remote Bridge
A remote bridge is capable of passing a data frame from one local area network to another when the two LANs are separated by a long distance and there is a wide area network connecting the two LANs.
A remote bridge takes the frame before it leaves the first LAN and encapsulates the WAN headers and trailers.
When the packet arrives at the destination remote bridge, that bridge removes the WAN headers and trailers leaving the original frame.

15. Hubs
As seen earlier, a hub interconnects two or more workstations into a local area network.
When a workstation transmits to a hub, the hub immediately resends the data frame out all connecting links.
A hub can be managed or unmanaged. A managed hub possesses enough processing power that it can be managed from a remote location (inventory, power, traffic).

16. Switches A switch is a combination of a hub and a bridge.
CISCO Catalyst3550
A switch is a combination of a hub and a bridge.
It can interconnect two or more workstations, but like a bridge, it observes traffic flow and learns.
When a frame arrives at a switch, the switch examines the destination address and forwards the frame out the one necessary connection.
Workstations that connect to a hub are on a shared segment
Workstations that connect to a switch are on a switched (dedicated) segment.

19. Function/Flexibility
Switches from CISCO
Catalyst 6500
Modular 10/100/1000
256 Gbps switching capacity
Layer 2-7 Switching
High Availability
Integrated Services Modules
Catalyst 4500
Modular 10/100/1000
64 Gbps switching capacity
L3/L4 Services
Redundant Supervisors and Power
Catalyst 3550
Stackable 10/100, inline power, and GE configurations
High performance switching and routing
Enterprise-class intelligent Layer 3/4 services
Clustering capable
Catalyst 2950
Price/Performance
Standalone/Stackable 10/100 switching
GBIC-based Gigabit connectivity
Basic and intelligent services
Clustering capable
Cisco provides the most comprehensive set of switching solutions in the industry, meeting the requirements of the smallest wiring closets to the most routing-intensive network cores. Here are platform descriptions to help you position Cisco's Catalyst offerings for mid-market customers and enterprise workgroups.
The Cisco Catalyst 2950 is a mainstream, standalone 10/100 switch. It delivers the optimal price point for 10/100 connectivity.
Wire speed forwarding on both desktop switches, or a full 4.5Gbps forwarding rate or 7.0 Mpps
Switch Clustering offers the industry’s most scalable native, multi-device management architecture available
Other mgmt options include CWSI, IOS, and SNMP
GBIC based implementation provides options for high-speed uplinks or utilization of our new ultra-low cost and versatile GigaStack stacking GBIC
Consistent with Cisco’s commitment to preserve and protect customers’ long-term investments, we’ve made our new technologies (stacking and management) backwards compatible with our existing stackable Catalyst switches.
The Cisco Catalyst 3500 XL is a stackable 10/100 and Gigabit Ethernet switch offering. It is ideal for customers who require a low entry price but need the flexibility to scale their workgroup beyond ports, simply and affordably.
The Cisco Catalyst T and G is the industry’s first stackable Multilayer 1000BASE-T Ethernet Switch, it is an ideal aggregator for customers who want to take advantage of the power IOS Intelligent Network Services while using their existing copper infrastructure.
The Catalyst T offers 10 10/100/1000BASE-T ports and 2 GBICs and the Catalyst G offers 10 GBICs and 2 10/100/1000Base T port, offering offering uplink media flexibility.
These switches offers a variety of powerful Intelligent Networks Services without compromising on performance.
Like all of Cisco’s stackable switches, it supports the award winning Cluster Management System (CMS) which allows administrators to configure and manage all the Layer 2 and Layer 3 features from a single Easy to Use GUI interface.
FOR Layer 3 GIGABIT AGGREGATION SWITCHES:
The Cisco Catalyst 4908G Layer 3 is a Multilayer Gigabit Ethernet switch with GBICs for flexible media options, it is an ideal aggregator for networks with deployed fiber backbones.
The Catalyst 4500 Series of switches is Cisco’s Premier Modular Enterprise and Branch office modular solution
Modular Layer2 with optional Layer3/4 engine
AVVID architecture with Voice integration and Services
With over 15 Million ports shipped in the history of the Catalyst 4000 family, Market acceptance has been strong
Modular architecture allows you to add WAN capabilities and gives the customer the option to deploy new technologies as they emerge
Wide variety of interfaces allow for Gigabit Ethernet or Fast Ethernet over copper or fiber
The Catalyst 6500 Series delivers high-speed Gigabit switching for distribution, core, and data center applications
Layer 2 to 7 IP service deployment.
Scalable performance: 256 Gbps backplane, over 210 million pps.
LAN/MAN/WAN: 10/100/1000, POS, ATM, T1/E1/OC3/12/OC48.
Intelligent network services: Security, QoS, multicast, high availability, Layer switching, voice/video/data convergence, policy management, server load balancing, and intrusion detection.
Catalyst 3508G XL
Stackable L2 GE aggregation
Clustering capable
Catalyst 2900 Series XL/ Modular
Low-cost 10/100 switching
Modular
Clustering capable
Function/Flexibility

20. Switches Support multiple LAN technologies
Very fast: cut-through architecture
Forward as soon as they arrive
Support multiple ports simultaneously
The backplane of a switch is fast enough to support multiple data transfers at one time.
Can be used to create a virtual LAN
Logical subgroup based on Switches and software
Use IEEE 802.1Q standard
Remotely configurable

24. Full Duplex Switches
A full duplex switch allows for simultaneous transmission and reception of data to and from a workstation.
This full duplex connection helps to eliminate collisions.
To support a full duplex connection to a switch, two sets of wires are necessary - one for the receive operation and one for the transmit operation.

26. Network Servers
Network servers provide the storage necessary for LAN software.
They are usually the focal point for the network operating system.
Increasingly, network servers are functioning as bridges, switches, and routers. By adding the appropriate card, a server can assume multiple functions.
Multi-processors, multiple disks, huge memory, etc.

27. Routers The device that connects a LAN to a WAN or a WAN to a WAN.
A router accepts an outgoing packet, removes any LAN headers and trailers, and encapsulates the necessary WAN headers and trailers.
Because a router has to make wide area network routing decisions, the router has to dig down into the network layer of the packet to retrieve the network destination address.

28. Routers Routers are often called “layer 3 devices”.
Routers often incorporate firewall functions.