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CA - Network design for high availability

File:Network_design_for_high_availability-CA_description.pdf

File:Network_design_for_high_availability-PacketTracerFile.zip

Group justification report

File:Network_design_for_high_availability-GroupJustificationReport.pdf

To make the decision of the more suitable network design for the new data center of Dublin Computer School (DCS), we consider the following specification provided in the description of the project:

• The fact that the business is home grown in Dublin and the organization is expanding rapidly both in Dublin and in many sites around Ireland,
• The growth expected by the Infrastructure Manager,
• The need of a new Moodle system and a CRM system for the Marketing department,

We can see that Dublin Computer School (DCS) is, without any doubt, expecting a significant growth for the next years. Therefore, based on this fact, and after evaluating the budget, we decided to go for an ambitious design that ensure not only availability and reliability but also scalability of the network. We have to take into consideration that this data center is going to be used for all the sites around Ireland, where the company is also expecting growing.

Dublin

As we have already mentioned, in the Dublin LAN we are going to place the new data center; but also, this network have to be designed to provided end user devices communication (Wired and Wireless).

In general, our design is based on the concepts described in the «Campus LAN and Wireless LAN Design Guide» of Cisco [\cite]. We built a hierarchical Three-Tier Design: Core, Distribution and Access layers.

At the beginning of the project, we though a Two-Tier Design was the most suitable option, but after consider many factors, the expected growing of the network tipped the scale in favor of the Three-Tier Design (See Figure \ref).

In Figure see we show the design for the Dublin network. Our design is composed by:

• A layer 3 switch in the core.
• Two layer 3 distribution switches.
• Four access switches.

VLANs

We created 4 VLANs:

• VLAN10 (Student)
• VLAN20 (Marketing)
• VLAN30 (HR)
• VLAN40 (Finance)
• VLAN99 (Management)

We perform the following settings:

• We configure the management interface (VLAN99) in every switch with an IP address
• 802.1Q Trunk Between the Switches (Manually configuration)
• In the access switches, we configured access ports for the end user devices and server and assigned VLANs to the correct switch interfaces (See Figure XX). The servers interfaces were assigned to the Management VLAN99.

Rapid spanning tree between switches

In our implementation, we made sure root bridge is in a suitable position. To do so, we manually configuring priority to influence the root election:

• We placed the root bridge in to core of our design for all VLANs
• We placed the root secondary in the distribution level of the network and configure Load Balancing sharing the root secondary between the 2 distribution switches.

MS1(config)#spanning-tree vlan 1,10,20,30,40,99 root primary

MS2(config)#spanning-tree vlan 1,10,20 root secondary
MS3(config)#spanning-tree vlan 30,40,99 root secondary

With this configuration, RSTP is avoiding redundant by blocking port mostly in the access layer.

Because we did load balancing sharing the root secondary between the 2 distribution switches, and because we are doing «Per-Vlan rapid spanning tree mode», the port blocked would depend on the VLAN. For example, if we consider S4. The rapid spanning tree protocol is blocking the F0/18 port for the VLANs where the root secondary is MS2. However, for the VLANs where the root secondary is MS3, rapid spanning is blocking the Fa0/14 port. That is why all the ports are shown in green in our network (none of the port in blocked for all VLANs) (See Figure XX).

Configuring 802 1Q trunk-based inter-VLAN routing

No key decisions had to be taken in this part, we just configure 802 1Q trunk-based inter-VLAN routing to provide routing for our multiple VLANs. You can verified all IP addresses and interfaces configured in the Addressing table.

Wireless access for a GUEST wifi network

The GUEST wifi network was configured using a wireless rourters attached to one of the access switches. In Figure XX we show the configuration performed. We attached the wireless router to VLAN10 and created a new wifi network. A DHCP server was also enable in the wireless router so the devices were are able to request an IP via DHCP (Figure xx)

Some security configurations were also performed:

• We configured a passphrase for the GUEST network: duboffice2019
• Enable encryption.

WAN

We created a WAN network connecting a total of 5 sites: Dublin, Galway, Limerick, Cork and Sligo. You can see the IP addresses in the Addressing table. They corespondent to the 10.0.0.0 network.

We make sure to include redundant paths between Dublin and Galway, which is the main concern of our WAN.

We configured OSPF Routing Protocol. OSPF is a widely used protocols with one of the lower Administrative Distance (110). That is why, in case of multiple routing protocols configured in a router (such as RIP or IS-IS), OSPF would be the defauld one and used to route packets. OSPF is able to determine the shortest path to a destination by adding the costs of each path to reach a destination.

Addressing table

	Device	Interface	IP Address	Subnet Mask	Default Gateway	Comments
Dublin	R1	G0/1.1	172.16.1.1	255.255.255.0
		G0/1.10	172.16.10.1	255.255.255.0
		G0/1.20	172.16.20.1	255.255.255.0
		G0/1.30	172.16.30.1	255.255.255.0
		G0/1.40	172.16.40.1	255.255.255.0
		G0/.1.99	172.16.99.1	255.255.255.0
		S0/0/0 DCE	10.16.1.1	255.255.255.252
		S0/0/1	10.16.2.1	255.255.255.252
		S0/1/0 DCE	10.16.3.1	255.255.255.252
	MS1	VLAN 99	172.16.99.11	255.255.255.0		Root primary for all VLANs
	MS2	VLAN 99	172.16.99.12	255.255.255.0		Root secondary for VLAN 1, 10, 20
	MS3	VLAN 99	172.16.99.13	255.255.255.0		Root secondary for VLAN 30, 40, 99
	S1	VLAN 99	172.16.99.21	255.255.255.0
	S2	VLAN 99	172.16.99.22	255.255.255.0
	S3	VLAN 99	172.16.99.23	255.255.255.0
	S4	VLAN 99	172.16.99.24	255.255.255.0
	Server1	G0 (vlan99)	172.16.99.80	255.255.255.0	172.16.99.1
		G1 (vlan99)
	Server2	G0 (vlan99)	172.16.99.82	255.255.255.0	172.16.99.1
		G1 (vlan99)
	PC1	NIC (vlan10)	172.16.10.51	255.255.255.0	172.16.10.1
	PC2	NIC (vlan20)	172.16.20.52	255.255.255.0	172.16.20.1
	PC3	NIC (vlan30)	172.16.30.53	255.255.255.0	172.16.30.1
	PC4	NIC (vlan40)	172.16.40.54	255.255.255.0	172.16.40.1
	Wireless router0	Internet setup	172.16.10.101	255.255.255.0	172.16.10.1
		Network setup	172.16.50.1	255.255.255.0
	Laptop1
	Laptop2
-
Limerik	R2	S/0/0/0	10.16.1.2	255.255.255.252
		S/0/0/1 DCE	10.16.4.1	255.255.255.252
		G0/0	172.18.1.1	255.255.255.0
	PC7	NIC	172.18.1.57	255.255.255.0	172.18.1.1
-
Galway	R3	S0/0/1	10.16.4.2	255.255.255.252		Standby router in HSRP Slow path
		S0/1/1	10.16.5.1	255.255.255.252
		G0/1	172.17.1.1	255.255.255.0
	R4	S0/0/0 DCE	10.16.6.1	255.255.255.252		Active router in HSRP (Because the other path is slow)
		G0/0	172.17.1.2	255.255.255.0
	Switch0	VLAN 1	172.17.1.6	255.255.255.0	172.17.1.254 (virtual IP for HSRP) 172.17.1.1
	Switch1	VLAN 1	172.17.1.7	255.255.255.0	172.17.1.254 (virtual IP for HSRP) 172.17.1.2
	PC5	NIC	172.17.1.55	255.255.255.0	172.17.1.254 (virtual IP for HSRP) 172.17.1.1
	PC6	NIC	172.17.1.56	255.255.255.0	172.17.1.254 (virtual IP for HSRP) 172.17.1.2
-
Cork	R5	S0/0/0	10.16.6.2	255.255.255.252
		S0/0/1 DCE	10.16.2.2	255.255.255.252
		G0/0	172.19.1.1	255.255.255.0
	PC8	NIC	172.19.1.58	255.255.255.0	172.19.1.1
-
Sligo	R6	S0/1/0	10.16.3.2	255.255.255.252
		S0/1/1 DCE	10.16.5.2	255.255.255.252
		G0/0	172.20.1.1	255.255.255.0	c
	PC9	NIC	172.20.1.59	255.255.255.0	172.20.1.1