ദ്ദി •⩊• )

Midterm Notes

2 min read

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Scenario Targets

  • POS (wired), Back Office (servers + PCs), Guest Wi‑Fi (isolated)
  • Must be reliable under peak load; use provided IPs; router interfaces via CLI

Topology (Star + VLANs)

  • R1 (router-on-a-stick), S1 (core), S2 (optional), WAP (Guest)
  • VLANs: 10=POS, 20=BackOffice, 30=Guest
  • Naming: R1, S1/S2, SRV-APP/DHCP/DNS, POS-1..N, BO-1..N, WAP-Guest

Cables

  • Host/Server/Router ↔ Switch: Copper straight-through
  • Switch ↔ Switch: Straight-through (or crossover if needed)
  • WAP ↔ Switch: Straight-through

IP Worksheet (fill in)

  • V10 POS: Net ___ Mask ___ GW ___
  • V20 BO: Net ___ Mask ___ GW ___
  • V30 Guest: Net ___ Mask ___ GW ___
  • Servers: APP ___ DNS ___ DHCP ___
  • DHCP Exclusions: POS – | BO – | Guest –

Router (Inter‑VLAN + DHCP)

enable
conf t
hostname R1
no ip domain-lookup
int g0/0
 no shut
int g0/0.10
 encap dot1q 10
 ip address <V10_GW> <MASK>
int g0/0.20
 encap dot1q 20
 ip address <V20_GW> <MASK>
int g0/0.30
 encap dot1q 30
 ip address <V30_GW> <MASK>
 
ip dhcp excluded-address <POS_START> <POS_END>
ip dhcp pool POS
 network <POS_NET> <MASK>
 default-router <V10_GW>
 dns-server <DNS_IP>
 
ip dhcp pool BO
 network <BO_NET> <MASK>
 default-router <V20_GW>
 dns-server <DNS_IP>
 
ip dhcp pool GUEST
 network <GUEST_NET> <MASK>
 default-router <V30_GW>
 dns-server <DNS_IP>
end
wr mem

Switch (VLANs, access, trunk)

enable
conf t
hostname S1
vlan 10; name POS
vlan 20; name BACK_OFFICE
vlan 30; name GUEST
 
int range fa0/1-8
 switchport mode access
 switchport access vlan 10
 spanning-tree portfast
int range fa0/9-16
 switchport mode access
 switchport access vlan 20
 spanning-tree portfast
int g0/1
 switchport trunk encapsulation dot1q
 switchport mode trunk
 switchport trunk allowed vlan 10,20,30
end
wr mem

Guest Isolation (optional)

conf t
ip access-list ext GUEST_OUT
 deny ip <GUEST_NET> <WCMASK> <POS_NET> <WCMASK>
 deny ip <GUEST_NET> <WCMASK> <BO_NET> <WCMASK>
 permit ip <GUEST_NET> <WCMASK> any
int g0/0.30
 ip access-group GUEST_OUT in
end
wr mem

Verify

  • L2: show vlan brief, show interfaces trunk
  • L3: show ip int brief, show ip dhcp binding, ping
  • Tests: POS ↔ POS; POS → Server; BO → Server; Guest → GW (not POS/BO if ACL)

OSI Nuggets

  • L2: Switches forward by MAC; VLAN tagging (802.1Q)
  • L3: Router subinterfaces = gateways between subnets
  • Need router to connect different subnets

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