The document discusses various topics related to network topology and design including hierarchical topologies, roles of different layers, VLANs, routing protocols, VPNs, firewalls, and more. A hierarchical topology divides a network into core, distribution and access layers with the core providing optimal transport, distribution implementing policies, and access connecting users. The SAFE architecture is a modular approach that analyzes functional, logical and physical network components to simplify enterprise design.

1. 1)What Is Topology?
A topology is a map of an internetwork that indicates network segments, interconnection points,
and user communities.
2)What is Hierarchial Topology?
A typical hierarchical topology is
■ A core layer of high-end routers and switches that are optimized for availability and
performance.
■ A distribution layer of routers and switches that implement policies. In small and
medium-sized organizations, the core and distribution layers can be combined.
■ An access layer that connects users via lower-end switches and wireless access points
3)What is the Roles ofHierarchial Model Layers?
Each layer of the hierarchical model has a specific role:
■ The core layer provides optimal transport between sites.
■ The distribution layer connects network services to the access layer and implements
policies regarding security, traffic loading
 In a WAN design, the access layer consists of the routers at the edge of the campus
networks. In a campus network, the access layer provides switches or hubs for enduser
access
4)What is Distribution Layer ofHierarchail Topology?
The distribution layer of the network is the demarcation point between the access and
core layers of the network. The distribution layer has many roles, including controlling
access to resources for security reasons and controlling network traffic that traverses theCore.
5)What is Access Layer in Hierarchial Topology?
The access layer provides users on local segments with access to the internetwork. The
access layer can include routers, switches, bridges, shared-media hubs, and wireless
access points.
6)What is Backdoor?
A backdoor is a connection between devices in the same layer. A backdoor can be an extra
router, bridge, or switch added to connect two networks. A backdoor can also be a hub.
7)What is Back Path?
Backup path consists of routers and switches and individual backup links
between routers and switches, which duplicate devices and links on the primary path.

2. 8)What is MPPP?
The Multilink Point-to-Point Protocol (MPPP) is an Internet Engineering Task Force (IETF)
standard for channel aggregation. MPPP ensures that packets arrive in sequence at the receiving
router.
9)What is meant by SAFE?
SAFE is a reference architecture that network designers can use to simplify the complexity
of a large internetwork. The architecture lets you apply a modular approach to network
design. With SAFE, you can analyze the functional, logical, and physical components of
a network and thus simplify the process of designing an overall enterprise network.
10)What is Spanning Tree Protocal?
The Spanning Tree Protocol (STP), is a protocol and algorithm, documented in IEEE 802.1D, for
dynamically “pruning” an arbitrary topology of connected Layer 2 switches into a spanning
tree.
11)What are the states ofRSTP?
RSTP stands for Rapid Spanning Tree Protocol .
The states of RTSTP are:
1)Discarding
2)Learning
3)Forwarding.
12)What is Bandwidth Domain?
A bandwidth domain is a set of devices that share bandwidth and compete for
access to the bandwidth.
13)What is Broadcast domain & Broadcast Frame?
A broadcast domain is a set of devices that can all hear each other’s broadcast frames. A
broadcast frame is a frame that is sent to the MAC address FF:FF:FF:FF:FF:FF. By default,
switches do not divide broadcast domains
14)What is VLAN?
A virtual LAN (VLAN) is an emulation of a standard LAN that allows data transfer to
take place without the traditional physical restraints placed on a network. A VLAN is a
set of LAN devices that belong to an administrative group
15)Whjat is Hot Standby Mode?
Hot Standby mode is a mode that supports two access points being configured
to use the same channel in a single coverage area. Only one of the access points is
active. The standby access point passively monitors the network and the primary access
point

3. 16)What is Storage Area network?
Storage-area network (SAN) are a popular solution for organizations seeking highly reliable,
uninterrupted access to large amounts of stored information.
17)What is HSRP?
HSRP stands for Hot Standby Router Protocol.HSRP works by creating a virtual router, also
called a phantom route. The virtual router has its own IP and MAC addresses. Each workstation
is configured to use the virtual router as its default gateway.
18)What is GLBP?
GLBP stands for Gateway Load Balancing Protocol .GLBP provides loadbalancing over
multiple routers using a single virtual IP address and multiple virtual MAC addresses. Each host
is configured with the same virtual IP address, and all routers in the virtual router group
participate in forwarding packets.
19)What is default Route?
A default route specifies where a packet should go if there is
no explicit entry for the destination network in a router’s routing table. The default route
is also sometimes called the gateway of last resort.
20)What is Virtual Private Networking?
Virtual private networks (VPN) are the networks which use advanced encryption and tunneling
to permit
organizations to establish secure, end-to-end, private network connections over a thirdparty
network.
21)What is meant by Firewall?
A firewall is a system or combination of systems that enforces a boundary between two
or more networks. A firewall can be a router with ACLs, a dedicated hardware box, or
software running on a PC or UNIX system. A firewall should be placed in the network
topology so that all traffic from outside the protected network must pass through the firewall.
22)What is meant by Buying Transit?
In common ISP relationship, is a provider-customer one, where a smaller ISP
pays a larger ISP for the privilege of sending traffic through the larger ISP’s network. This
is often called buying transit.

4. 23) What is Campus Network?
 Campus network design topologies should meet a customer’s goals for availability and
performance by featuring small bandwidth domains, small broadcast domains, redundancy,
mirrored servers, and multiple ways for a workstation to reach a router for off-net
communications.
 Campus networks should be designed using a hierarchical, modular
approach so that the network offers good performance, maintainability, and scalability.
 A campus network consist of access, distribution, and core layers.
24)What are the modules ofSAFE architecture?
SAFE architecture comprises the following major modules:
 Core
 Data Center
 Campus
 Management
 WAN Edge
 Internet Edge
 Branches
 Extranet
 Partner Site
 E-Commerce
 Teleworker
 Cisco Sensor Base
25)What is meant By Core Layer?
 The core layer of a three-layer hierarchical topology is the high-speed backbone of the
internetwork. Because the core layer is critical for interconnectivity, you should design
 The core layer with redundant components.
 The core layer should be highly reliable and should adapt to changes quickly.