Ping Command

What does ping do?

• It sends small packets (ICMP Echo Requests) to a target.

• The target replies with Echo Replies.

• From this, you learn:

  • If the target is reachable.

  • How long it takes for packets to travel (latency).

  • If there is packet loss.

Basic Syntax

ping <target>

Topology

• User LAN → Router R1 fa0/0 (192.168.1.1/24)

• Server LAN → Router R1 fa0/1 (192.168.2.1/24)

Addressing Plan

Device	IP Address	Subnet Mask	Gateway
Manager PC	192.168.1.10	255.255.255.0	192.168.1.1
Staff PC	192.168.1.20	255.255.255.0	192.168.1.1
File Server	192.168.2.100	255.255.255.0	192.168.2.1
Router R1 (fa0/0)	192.168.1.1	255.255.255.0	192.168.1.1
Router R1 (fa0/1)	192.168.2.1	255.255.255.0	192.168.2.1

Router Configuration

Step 1: Configure Router Interface

Router>enable 
Router#configure terminal 
Router(config)#interface fastEthernet 0/0
Router(config-if)#description Link-To-Users
Router(config-if)#ip address 192.168.1.1 255.255.255.0
Router(config-if)#no shutdown 
Router(config-if)#exit
Router(config)#interface fastEthernet 0/1
Router(config-if)#description Link-To-Server
Router(config-if)#ip address 192.168.2.1 255.255.255.0
Router(config-if)#no shutdown 

Step 2: Configure ACL on Router

We want:

• Manager (192.168.1.10) → can ping & access file server

• Staff (192.168.1.20) → can access file server but cannot ping

Router(config)#access-list 101 deny icmp host 192.168.1.20 host 192.168.2.100
Router(config)#access-list 101 permit ip any any
Router(config)#interface fastEthernet 0/0
Router(config-if)#ip access-group 101 in

Testing the Scenario

• From Manager PC → ping 192.168.1.100 ✅ Success (ICMP allowed).

PC>ping 192.168.2.100

Pinging 192.168.2.100 with 32 bytes of data:

Reply from 192.168.2.100: bytes=32 time=0ms TTL=127
Reply from 192.168.2.100: bytes=32 time=1ms TTL=127
Reply from 192.168.2.100: bytes=32 time=0ms TTL=127
Reply from 192.168.2.100: bytes=32 time=0ms TTL=127

Ping statistics for 192.168.2.100:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms

PC>

• From Staff PC → ping 192.168.1.100 ❌ Fail (Request timed out) — ACL blocked ICMP.

PC>ping 192.168.2.100

Pinging 192.168.2.100 with 32 bytes of data:

Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.
Reply from 192.168.1.1: Destination host unreachable.

Ping statistics for 192.168.2.100:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

PC>

• From Staff PC → Access File Server app (e.g., HTTP or SMB). ✅ Success (ACL permits all other IP traffic).

Cisco Packet Tracer (Version 6.2.0.0052)

105KB

ping-command.pkt

Open

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Keywords

ACL, Cisco, Router, Switch, Ping, ICMP, Access Control, Permit, Deny, Staff, Manager, File Server, Subnet, Interface, Inbound, Outbound, Packet Filtering, Security Policy, Network Access, Troubleshooting, Nerd Cafe , نرد کافه

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