- BSCI Exam cram
||CCNP-BSCI (Building Scalable Cisco Internetworks) exam is a requirement towards obtaining CCNP
certification. Skills measured are: Designing and
implementing complex routed WANs including EIGRP, OSPF,
BGP, and IS-IS. Valid CCNA certification is a pre-requisite for obtaining
be CCNP certified, the following exams need to be
Study material covering exam
Cisco Internetworks or BSCI
Multi-layer Switched Network or BCMSN
Remote Access Networks
Alternatively, one can take the following exams
to obtain CCNP certification:
Study material covering exam
Scalable Cisco Internetworks (BSCI)
Multi-layer Switched Network.
Remote Access Networks.
The BSCI exam is of 75min duration and there will be
approximately 65 questions. You need to score 690 or
more to pass the exam. Visit
the official website here.
1. Scalable networks:
The key 5 characteristics of Scalable
- Reliable and available: An internetwork is usually up
for 24 hours a day and seven days a week.
- Efficient: Efficiency means optimization of resources
keeping in view available bandwidth. An internetwork
should have less amount of overhead traffic, such as
broadcasts, routing updates etc.
- Responsive: It is necessary that the internetwork
requirements for different protocols. Cisco IOS has
been developed keeping in view the QoS demands.
Different protocols may require different QoS
- Adaptable: An internetwork should be able to
accommodate variety of
networks and protocols. The available
protocols may include for example, TCP/IP, IPX, and
SNA. An adaptable internet should be able to
accommodate legacy as well as more recent
technologies such as VOIP.
- Accessible and Secure: An internet should be
accessible by using different access methods, such
as dial-up, dedicated, switched connections. At the
same time, it should provide secure environment.
2. The typical three-layer hierarchical
internetworking model consists of the following:
layer: Core layer is responsible to provide an
optimal and reliable transport structure. The core
layer is the backbone network of the entire
internetwork and may include LAN and WAN backbones.
Core layer usually consists of fully redundant paths
with technologies such as FDDI, Fast Ethernet, and/
layer: Distribution layer is responsible to provide
access to the internetwork as well as to the
servers. Distribution layer sits between the Core
layer and the Access layer. The policies such as
ACLs are implemented at the distribution layer.
Distribution layer is also known as workgroup layer.
layer, provides the users, access to the resources
In real world, a single
device may be functioning at both Access layer as well
as distribution layer. This is true for even Core layer.
3. Network segmentation:
Network congestion can be addressed by
segmentation of the network. Network segmentation, also
called micro segmentation, can be done by using:
- Routers, and
The primary purpose of segmentation is to
reduce congestion in the network.
4. Bridges and switches forwards all
broadcasts, which puts extra load on the network. In
other words, though bridges divide the network into
different collision domains, the broadcast domain remain
only one. This increases the overhead on the network.
5. The Cisco IOS features that allow reduction
in bandwidth are:
- Access Control Lists: ACLs are used to permit or deny
protocol update traffic, data traffic, and broadcast
traffic. Cisco access lists are available for IP,
IPX, and AppleTalk protocols.
- Snapshot routing: Snapshot routing can reduce WAN
costs, by exchanging the routing table at predefined
intervals. The routing tables for the distance
vector protocols are kept frozen until the next
update occurs. Snapshot routing is used only on
distance vector protocols such as IP RIP. Snapshot
routing is widely used on ISDN lines.
- Compression over WANs: Cisco IOS supports TCP/IP
packet header, as well as data compression. Link
compression is also supported, that compresses both
header and data information in packets across point
to point connections.
- DDR (Dial on Demand Routing): DDR are useful when the
traffic flow is not continuous in nature. In DDR,
channel is created only after intended traffic is
detected by the router, by dialing the destination.
- Switched network access: Switched networks, such as
Frame Relay, X.25 can share the bandwidth by
establishing virtual circuits.
- Optimization of routing table size: Routing table
entries consume bandwidth and processing power.
These entries can be reduced by techniques such as
route summarization, and incremental updates.
6. Snapshot routing builds routing table based
on a snapshot of a dynamic routing table available when
the network is active. The snapshot routing table is
used until another activity occurs on the network, at
which time the routing table is rebuilt. No routing
information is exchanged when the network is quiet.
Snapshot routing can be applied to distance vector
protocols such as IP RIP, IGRP, IPX RIP, and RTMP.
7. Cisco IOS supports the following queuing
- Weighted fair-queuing: This is an automatic queuing
method that provides fair bandwidth to all network
- Priority queuing: Here, one particular type of traffic
is given priority over all other types of traffic.
Thus this particular traffic, for which priority is
given, is assured of bandwidth. All other types of
traffic do not have assured bandwidth.
- Custom queuing: Here, each traffic type gets a
pre-allocated bandwidth. Certain types of traffic
can be allocated higher bandwidth depending on the
RIP (and IGRP) always summarizes routing
information by major network numbers. This is called
IP RIP based networks send the complete routing
table during update. The default update interval is 30
RIP version 2 is a classless routing protocol,
where as RIP version 1 (RIP 1) is a classful routing
protocol. The disadvantage of classfull routing is that
some address space may be wasted. In classless routing,
routing protocols exchange the subnet mask information
during periodic routing updates. This allows variable
subnet masks to be used in the network, allowing better
use of address space. For example, a WAN link may need
only two IP addresses. If you use classless routing
protocol with, say 6 bits for subnetting (62-2 subnets),
only 2 subnet addresses are utilized and the remaining
become wasted. On the other hand, if you use classless
routing protocol, Variable Length Subnet Mask (VLSM) can
be used within the network, giving only 2 valid
addresses for the WAN link, thus saving valuable address
space. (If you are using IP addresses, address space
involves IP addresses).
9. Metric limit for link-state protocols is
10. Convergence is the term used to describe
the state at which all the internetworking devices, running specific routing protocol, are having the same
information about the internetwork in their routing
tables. The time it takes to arrive at common view of
the internetwork is called Convergence Time.