David Sudjiman

Can’t wait to do the next one. Seems like this journey never ends. But I like it anyway.

Today, I just passed Cisco ARCH 642-871 (Designing Cisco Network Architectures). I was using CCDP Self-Study: Designing Cisco Network Architectures (ARCH) (ISBN-10: 1-58705-185-0; ISBN-13: 978-1-58705-185-2) and believe me, it was like doing CCDA, full of stuff to memorize.

Anyway, I’ve made a quick summary for myself that I can carry during my lunch or toilet time to help me to memorize it. It’s not everything you need to pass ARCH exam, but at least to start with something. Have fun!

Primary Concerns of Network Deployment
- Performance
	- Responsiveness
	- Throughput
	- Utilization
- Scalability
	- Topology
	- Addressing
	- Routing Protocols
- Availability
	- Device fault tolerance and redundancy
	- Link Redundancy
	- Protocol Resiliency
	- Network Capacity Design.

Major Components of the Cisco AVVID
- Common Network Infrastructure
	- Application servers and clients
	- Network platforms
- Intelligent Network Services
	- Network Management
	- High Availability
	- Security
	- QoS
- Network Solutions
	- VPN
	- Wireless
	- IP Telephony
	- Content Networking
	- Storage Networking

Benefits of Cisco AVVID
- Integration
- Intelligence
- Innovation
- Interoperability

Hierarchical Network Model
- Access Layer
- Distribution Layer
- Core Layer

Enterprise Composite Network Model
- Enterprise Campus
	- Campus Infrastructure module
		- Building Access layer
		- Building Distribution layer
		- Campus Backbone
	- Network Management module
		- Intrusion Detection
		- System Logging
		- Authentication
		- Network Monitoring
		- Configuration Management
	- Server Farm module
	- Edge Distribution module
- Enterprise Edge
	- E-Commerce
		- Web Servers
		- Application servers
		- Database servers
		- Security devices
	- Internet Connectivity
		- Email servers
		- DNS servers
		- Public servers
		- Security devices
		- Edge Routers
	- Remote Access/VPN
		- Dial-in Access concentrators
		- VPN concentrators
		- Firewalls and Intrusion Detection System
		- Layer 2 Switches
	- WAN
- Service Provider Edge
	- ISP module
	- PSTN module
	- FR/ATM/PPP module

The design of an enterprise campus network must meet these requirements:
- Functionality
- Performance
- Scalability
- Availability
- Manageability

To design an enterprise campus network, following series of steps to be completed:
1. Determine application and data requirements for each campus
2. Design the logical network
3. Design the physical network
3. Select appropriate Cisco network Devices
4. Select and IP addressing strategy and numbering scheme
5. Select a routing protocol
6. Design the Edge Distribution module

Important factors when analyzing traffic.
- Traffic load measurement
- Traffic Types
- Smapling methods

Identifying IP addr
1. Determine the network size
2. Determine if you need private or public
3. Determine a method to implement IP addressing hierachy.

Methods to augment performance and scalability
- Increate port density
- Add higher-speed interfaces
- Consider the spanning-tree impelementation
- Implement a modular design

To mmet server farm module manageability requirements, consider the following items:
- Identify critical devices and applications
- Create and operations and support plan
- Implement 24/7 monitoring of servers and network equipment
- Implement problem/resolution procedures
- Create a business continuitu plan in case of a natural disaster

Typical requirements of the Enterprise Edge are
- Specific functionalities
- Performance
- Scalability
- Availability
- Manageability
- Cost effectiveness

Important characteristics of network applications at the Enterprise Edge functional are are
- Bandwidth
- Delay
- Loss

Requirements for WAN solution:
- Cost effectiveness
- Sufficient bandwidth
- High Link Quality
- Reliability
- Specific/appropriate data-link protocol characteristics
- Either always-on or on-demand characteristics

Common data-link layer tech.
- PPP
- Frame Relay
- ATM
- MPLS
- X.25

Common Physical layer tech.
- Leased Line
- DSl
- Dial-UP
- ISDN
- Optical Carrier

Enterprises implement high availability to meet the following requirements:
- Ensure that mission-critical applications are available
- Improve employee and customer satisfaction and loyalty
- Reduce reactive UT support costs, resulting in increased IT productivity
- Reduce financial loss
- Minimize lost productivity

Availability = MTBF / (MTBF+MTTR)

A Cisco high-availability solution has the following requirements:
- Reliable, fault-tolerant network devices
- Device and link redundancy
- Load balancing
- Resilient network technologies
- Network design
- Best Practices

Cisco IOS software provised the following L3 redundancy feature:
- HSRP or VRRP
- Fast Routing protocol convergence
- EtherChannel Technology
- Load Sharing
- CEF

To design high-availability service for an enterprise network one must answer the following types of questions
- Where should module and chassis redundancy be deployed.
- What software reliability features are required for the network?
- What protocol attributes need to be considered?
- What high-availability features are required for circuits and carriers?
- What environmental and power features are required for the network?
- What operations procedures are in place to prevent outages?

To fully determine the benefit of device, chassis, and link redundancy, one should
discover the answers to the following questions:
- Will the solution allow for load sharing?
- Which components are redundant?
- What active-standby fault detection methods are used?
- What is the MTBF for a module? What is the MTTR for a module? Should it be made redundant?
- How long does it take to do an upgrade?
- Are hot swapping and online, insertion and removal (OIR) available?

Cisco Systems recommends implementing the following software features:
- Protect gateway routers with HSRP or VRRP
- Implement resilient routing protocols, such as EIGRP, OSPF, IS-IS, RIPv2, BGP
- Use floating static routes and access control lists to reduce load in case of failure

Because the carrier network is an important component of the enterprise network and its
availability, careful consideration of the following points about the carrier network is
essential:
- Understand the carrier network
- Consider multihoming to different vendors
- Monitor carrier availability
- Review carrier notification and escalation procedures to reduce repair times

The general network design conclusions with respect to high availability are
- Reduce complexity, increase modularity and consistency
- Consider solution manageability
- Minimize the size of failure domains - Consider protocol attributes
- Consider budget, requirements, and areas of the network that contribute the most
downtime or are at greatest risk
- Test before deployment

Cisco has developed a set of best practices for network designers to ensure high
availability of the network. The five-step Cisco recommendations are
1 Analyze technical goals and constraints.
2 Determine the availability budget for the network.
3 Create application profiles for business applications.
4 Define availability and performance standards.
5 Create an operations support plan.

Within the Enterprise Edge functional area, the following must be considered for high
availability:
- Service level agreement
- Link redundancy
- Load balancing
- Policy-based routing
- Routing protocol convergence

Network reliability is mainly a function of the following factors and how much control
the network administrators have over them:
- Delay (packetization, serialization, propagation)
- Delay variation (fitter)
- Packet loss

Using QoS technologies, network engineers/administrators can do the following:
- Predict response times for end-to-end network services
- Manage jitter-sensitive applications and delay-sensitive traffic
- Control loss in times of congestion
- Set traffic priorities across the network
- Support dedicated bandwidth
- Avoid and manage network congestion

The two QoS architectures used in IP networks are
- Integrated Services (IntServ) model
- Differentiated Services (DiffServ) model

The three basic levels of end-to-end QoS that can be provided across a heterogeneous
network are
- Best-effort service
- Differentiated service
- Guaranteed service

To deploy QoS in a network, the following tasks need to be performed; each task requires
certain tools and technologies, and needs to be implemented at specific spots:
- Classification and marking
- Congestion avoidance
- Congestion management
- Traffic conditioning
- Signaling
- Link efficiency mechanisms

The Cisco-recommended QoS specifications for voice traffic are
- One-way latency should be no more than 150 to 200 ms.
- Jitter should be no more than 30 ms.
- Packet loss should be no more than 1 percent.
- 17 to 106 kbps of guaranteed priority bandwidth is required per call (depending on the sampling rate, codec, and Layer 2 overhead).
- 150 bps (+ Layer 2 overhead) per phone of guaranteed bandwidth is required for voice control traffic.

The Cisco-recommended QoS specifications for video conferencing are
- One-way latency should be no more than 150 to 200 ms.
- Jitter should be no more than 30 ms. - Packet loss should be no more than 1 percent.
- The minimum bandwidth guarantee is the size of the video conferencing session plus 20 percent.

The Cisco-recommended QoS specifications for streaming video traffic are
- Latency should be no more than four to five seconds, depending on the video application's buffering capabilities.
- There are no significant jitter requirements.
- Packet loss should be no more than 2 percent.
- Bandwidth requirements depend on the encoding and rate of video stream.
- Nonentertainment streaming video should be provisioned into the silver (guaranteed bandwidth) data-traffic class.

IP multicasting has the following characteristics:
- Transmits IP datagrams to a host group identified by a single IP destination address. A host group is dynamic and can contain zero or more host devices at any given time.
- Delivers a multicast packet to all members of the destination host group with the same best-effort reliability as regular unicast IP datagrams.
- Supports dynamic membership of a host group.
- Supports all host groups regardless of the location or number of members.
- Supports the membership of a single host in one or more multicast groups.
- Upholds multiple data streams at the application level for a single group
address.
- Supports a single group address for multiple applications on a host.

Some of the advantages of multicast transmission over unicast transmission are
- Enhanced efficiency -Available network bandwidth is utilized more efficiently, because multiple streams of data are replaced with a single transmission.
- Optimized performance-Fewer copies of data require less forwarding and processing.
- Distributed applications-In a unicast transmission, multipoint applications will not be possible as demand and usage grow, because unicast transmission will not scale.

Some disadvantages of multicast transmission are
- Best-effort delivery -Drops are expected to happen.
- No congestion avoidance-Lack of TCP windowing and slow-start mechanisms can result in network congestion.
- Duplicates-Some protocol mechanisms result in the occasional generation of duplicate packets.
- Out-of-order delivery-Some protocol mechanisms result in out-of-order delivery of packets.

Muticast forwarding has the following characteristics:
- Multicast routing is different from unicast routing-Unicast routing is concerned about where the packet is going, but multicast forwarding is concerned about where the packet came from and where the interested recipients might be.
- Multicast routing uses Reverse Path Forwarding
- A router forwards a multicast datagram only if received on the upstream interface toward the source; the routing table used for multicasting is checked against the source IP address in the packet.

In addition to multicast routing protocols, other supporting multicast protocols and control mechanisms are needed for efficient operation of multicast traffic in a network:
- IGMP is used by IPv4 hosts to communicate multicast group membership to the connected routers.
- CGMP is a Cisco-developed protocol that allows data-link layer switches to leverage IGMP information on Cisco routers to make data-link layer forwarding decisions. CGMP allows switches to forward multicast traffic to only those ports that are interested in the traffic.
- IGMP snooping serves the same purpose as CGMP; it requires the LAN switch to examine (snoop) IGMP packets sent from IP hosts to the router so that it can adjust its MAC table and avoid flooding multicast traffic.

When designing an enterprise wireless network, consider the following:
- RF design
- Campus infrastructure
- High availability
- Roaming
- IP multicast
- QoS

You must choose one of the following as the security model for a wireless LAN
implementation:
- EAP
- IPSec
- WEP

Content Networking support
- Bandwidth Optimization
- Server Scalability
- Response time reduction
- Large-scale deployment of rich content such as video or audio

Contect networking solution include
- Content edge delivery
- Content switching
- Content routing
- Content delivery and management

Two network storage model
- Network-attached storage
- SAN

The core storage networking technology enablers that provide universal access and interconnection are
- IP
- Gigabit Ethernet
- Fibre Channel
- Optical networking