Below you will some snippets of one of the CCDE Bootcamp scenario exercises along with 4 sample questions / tasks.
 

Design Scenario 1

Star Networks is the 3rd largest mobile phone operator in Sweden / Stockholm. Founded as a start-up company 8 years ago it is now a major player especially in the prepaid market. Star Networks’ IT Network has undergone a number of changes over the years. The present-day network is in need of a re-design that will follow a structured architecture, is scalable for future growth and will aid problem determination. The network has evolved very quickly where solutions have been deployed in the past with limited staff and resources. This resulted in building several different solutions for specific requirements, which are not based on a common architecture. Different “islands” of networks make it hard to troubleshoot problems and also very difficult to introduce new services or extend the reach of the network.

A common architecture should help during troubleshooting as every device, service or communication follows a specific, standardized flow. Also, most configurations are static and very little intelligence is build into the network to automatically compensate for problems that could arise (e.g. no dynamic routing protocols). Management is difficult to achieve due to the fact there is no general rule about how a device is being managed. Current management products are not implemented for all devices and the role of these products are not defined well enough. As there are different data flows through the network it is crucial to protect these data flows from each other. Network virtualization as a solution is difficult implement with the current design (except for some point solutions).

The company is separated into two large departments.

A. IT Department who is responsible for all IT equipment in the Campus and branch offices (“IP guys”)
B. Transmission Department who is responsible for the mobile phone / 3G /UMTS network (ATM,TDM, GGSN, Base stations, etc)

Currently these two departments both have their “own” networks. The IT Department is responsible for their HQ site located at Kings Road (approx. 600 users), 3 more buildings in nearby streets (River Street 1 and 2 and Park Street) – each with 150 to 250 users. These buildings are connected with 1*1Gig links (Ethernet) to Kings Road. The majority of all Servers are located in Kings Road.

They also just recently rent 2 floors in a Data Center on the other side of Stockholm in order to host redundant servers. The IT departments currently uses an ATM link with 2*70Mbit/sec in order to connect to TELECITY. The fibre is owned by the transmission department. There are 3 remote offices with 10 to 30 users (one in Stockholm, one in Uppsala and one in Malmo). The users currently have local servers with no backup facility. Also, they use some central services with quite bad performance.

In order to sell the phone contracts or prepaid cards there are 40 shops throughout Sweden. These are currently connected with 128k dial up links. They are similar to remote offices but with just two to three users. The plan is to migrate the dial links to DSL services. Star Networks had some initial experience with Multicast, but due to the current network that deployment failed and applications where changed to Unicast. Even though there is no current requirement for Multicast, the network should be build in a way that Multicast could be deployed at a later stage.

All of this currently is for Star Networks employees – not for the transmission of the data of the actual mobile phone customers (voice and data). This is handled by the transmission team. Not just do they need high bandwidth (especially in the future with 3G) – but they also request a SLA of 99.999% availability (5 minutes outage costs 50.000 USD in call time from the customers) and <50ms interruption for switching to a backup link (what they are used to from their SONET environment). The new design however should also have one common network for the transmission and IT. Also, Star Networks needs to connect to several 3rd party providers for exchanging Text, GPRS and other data. 3rd party connects are currently deployed in the IT as well as in the Transmission team.

 

QUESTION 1:
One major aspect for developing the new network was identified as to provide virtualization. There should be one physical network, which can act as several virtual networks for employees (divided into Windows and Unix network) – end-customer data (voice and UMTS from mobile phones) – shops network (customer care PCs, Tills, Web Servers) – and other future services.

Please complete the following table to help Star Networks on deciding for the correct virtualization technology: 

Technology	Easy	Scalable	Supports Transmission Dep. Requirements	Supports IT Dep. Requirements	Future proof
IPSec VPN
DMVPN
ATM PVCs
MPLS L3 VPN
MPLS L2 VPN (AToM)
GRE Tunnels
VRF Lite

<skipped>


QUESTION 4:
Email from Transmission Dep.
From: rich @ mystarnetworks.se
To: martin @ ccdebootcamp.com
Date: 07-December 2009 - 15:43h
Subject: Query

Hi Martin,

I know you are currently designing the new IT network for Rob (IT) with the goal to also use this new network for transmitting the actual user data (phone calls and UMTS). I know you packet guys can probably supply for enough bandwidth and can build a redundant network, but for our signalling we need <50ms failover-time if one of these link fails and we use the “backup” (this is a requirement from our signalling protocol which we cannot change). Your IP routing protocols are just no as fast as our SONET timers. How would you solve this issue?

Thanks,
Rich

A) OSPF/IS-IS timer tuning
B) MPLS FRR
C) Ether Channel
D) NSS+SSO
E) MPLS Traffic Engineering
F) Free text answer:


Explain your Decision

 

<skipped>


QUESTION 10
Email from IT Department.
From: rob @ mystarnetworks.se
To: martin @ ccdebootcamp.com
Date: 07-December 2009 - 18:02h
Subject: Request from Rob (IT)

Martin,

As discussed we need to implement QoS in order to guarantee the SLAs for certain applications. Especially the transmission department is not 100% convinced that we can provide them with a system that can be used instead of their ATM / TDM network. Also I think from a QoS perspective I was thinking of marking traffic even more than just video/voice/signalling….as we will have SAN traffic, more stringent latency requirements than other traffic and then even down to applications – top-up apps (can’t top up can’t make a call), billing/charging apps (makes the money), customer apps (customer facing apps), business apps (general in house non customer affecting apps) and best effort.

Now that’s just top of my head and its been a long day...
Other applications which are important to Star Networks (External refers to “customer traffic from mobile phones” currently transported on the transmission network):

- External VoIP (mobile phones)
- External Video (video telephony – in testing now)
- Internal VoIP (traffic from VoIP phones of Star Networks employees)
- Internal Video conferencing

What QoS classes would you recommend?


<skipped>


QUESTION 25:
The new network should also be ready for IPv6 applications. As there are more and more mobile phones, Star Network wants to be one of the first providers to also provide IPv6 connectivity for new Smart phones. Even though the customer and market might not be ready yet, they want to make sure that the new MPLS core is.

What would you recommend for Star Networks?

- as the new Core is MPLS based, it can support IPv6 from a network perspective
- start testing and familiarize your team with IPv6 in test labs and similar
- Verify every equipment being used for IPv6 compatibility
- Register IPv6 AS and address space

Explain your answer and describe the way forward:

 

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