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Computer Networks in Packet Tracer for intermediate users - ebook
Computer Networks in Packet Tracer for intermediate users - ebook
The book: Computer networks in packet tracer for intermediate users is designed for people who want to expand their skills and knowledge in the field of managing LAN and WAN networks. The reader finds here descriptions and practical exercises on configuring CISCO devices. It is a continuation of the first book with the same title. The authors have adopted the principle: minimum of theory, maximum of practical examples which will enable the reader to learn how to administer ICT networks in many complex device configurations without the need to purchase expensive CISCO equipment. The content of the book covers the basics of configuring protocols, services and network techniques such as: dynamic routing RIP, EGIRP, OSPF, eBGP, static routing, access control lists VoIP, STP, RS,VTP, FRAME RELAY, PPP, PAP and CHAP authentication RADIUS, NETFLOW, NAT, L2NAT, VPN tuneling. This part also includes configuring multilayer switches 3560-24PS and 3650-24PS. The authors of this book are an intergenerational and interdisciplinary team. Talented student of the Communications School Complex in Gdansk Damian Strojek. His passion is computer networks, and he holds certifications CCNA R&S and CCNA Security. Jerzy Kluczewski, a long-time CISCO CCNA Academy instructor. He already has several book publications to his credit about the Packet Tracer simulator. He gained his experience while working in industry and is currently a lecturer at the Gdansk School of Banking. Translation: a very talented student of applied linguistics at Silesian University in Katowice – Julia Skutela. She has been studying English and Russian to become a professional translator. Eager to expand her knowledge and building a workshop of the translator she has decided to raise up to the challenge of translating the following book into English.
| Kategoria: | Computer Technology |
| Język: | Angielski |
| Zabezpieczenie: |
Watermark
|
| ISBN: | 978-83-65645-87-6 |
| Rozmiar pliku: | 21 MB |
FRAGMENT KSIĄŻKI
13.1 Introduction to L2NAT
L2NAT ( Layer 2 Network Address Translation ) allows a unique public IP (global) address to be assigned to an existing private IP address, providing the ability to communicate private subnets with public subnets.
L2NAT supports two translation tables: one stores the translation definitions of private addresses to public (global) addresses, and the other stores the translation definitions of public (global) addresses to private addresses. The translations are defined based on the physical addresses of the end devices.
The limitations of the L2NAT service are as follows:
Cisco IOS version15.0 (2)EB minimum required,
only IPv4 addresses can be translated,
if L2NAT translation is configured for a host, it should not be configured as a DHCP client.
Requirements:
you must use a switch that includes the L2NAT service (in Packet Tracer, this is the IE 2000 switch),
you must configure so-called instances that define address translations,
L2NAT instances must be assigned to an interface or VLAN.
13.2 L2NAT Operating Diagram
Figure 13.1 L2NAT operating diagram.
Assumption: PC1 performs a ping to the global address of PC2. ping 10.1.1.2
Step-by-step analysis of the L2NAT translation operation:
1 – packet in the direction from PC1 to PC2 before translation
Figure 13.2 Packet from PC1 to PC2 before translation is performed. 2 – Packet in the direction from PC1 to PC2 after translation
Figure 13.3 Packet from PC1 to PC2 after translation.
3 - Return packet in the direction from PC2 to PC1 before translation.
Figure 13.4 Packet from PC2 to PC1 before translation.
4 - Return packet in PC2 to PC1 direction after translation
Figure 13.5 Packet from PC2 to PC1 after translation.
Operations in the direction from PC1 to PC2:
A frame arrives from the internal network and is to be forwarded to the external network.
The switch searches the Layer 2 NAT table.
The Layer 2 NAT table contains an entry that matches the local source address
inside from host 10.1.1.1 to 100.1.1.1
The switch converts the local address to a global address, which is 100.1.1.1 .
The switch searches the Layer 2 NAT table.
The Layer 2 NAT table contains an entry that matches the global destination address
outside from host 100.1.1.2 to 10.1.1.2
The switch converts the global address to the local address, which is 10.1.1.2 .
Operations in the direction from PC2 to PC1:
A frame arrives from the external network and is to be forwarded to the internal network.
The switch searches the Layer2 NAT table.
The Layer 2 NAT table contains an entry that matches the local source address
outside from host 100.1.1.2 to 10.1.1.2
The switch converts the local address to a global address, which is 100.1.1.2 .
The switch searches the Layer2 NAT table.
The Layer 2 NAT table contains an entry that matches the global destination address.
inside from host 10.1.1.1 to 100.1.1.1
The switch converts the global address to a local address, that is, to 10.1.1.1 .
13.2.1 Example of the Simple L2NAT Configuration
Addressing table
Table 13.1 Addressing table.
Topology
Figure 13.6 L2NAT topology.
Configuring a simple topology with L2NAT is done in the following steps. Step 1. Connect two computers to the IE 2000 switch according to the topology. Step 2. Configure the IP addresses of the computers according to the addressing table Step 3. Configure an L2NAT instance named OUTSIDE on the IE 2000 switch. enable
conf t
l2nat instance OUTSIDE
inside from host 10.1.1.1 to 100.1.1.1 outside from host 100.1.1.2 to 10.1.1.2
Step 4. Assign the OUTSIDE instance to an interface on the IE 2000 interface Gi1/1
l2nat OUTSIDE
Step 5 . Check with the ping command the communication between the computers From the command line of PC1 (global address of PC2), execute: ping 10.1.1.2
From the command line of PC2 (global address PC1), execute: ping 100.1.1.1
13.2.2 Handling repeating IP addresses in L2NAT
The following example shows how, using the L2NAT service, you can configure repeating IP addresses (duplicate IP addresses). Here we will use two IE 2000 switches and one 2950 switch.
Addressing table
Table 13.2 Addressing table.
Switch configuration table - Part 1
Table 13.3 Switch configuration table - Part 1.
Switch configuration table – Part 2
--
--
Table 13.4 Switch configuration table - Part 2.
Topology
Figure 13.7 Network topology.
Configuring the above topology with L2NAT is done in the following steps. Step 1. Connect the devices according to the topology.
Step 2. Configure the IP addresses of the computers according to the addressing table, switch configuration tables (Part 1, 2).
Step 3. Configure the L2NAT service named A-Subnet on the SW-A switch according to the switch configuration table (Part 2).
enable
conf t
l2nat instance A-Subnet
inside from network 192.168.1.0 to 10.1.1.16 mask
255.255.255.240
outside from host 0.1.1.254 to 192.168.1.254 outside from network 10.1.1.32 to 192.168.1.32 mask
255.255.255.240
Step 4. Assign the A-Subnet instance to an interface on the SW-A switch. interface Gi 1/1
l2nat A-Subnet
Step 5. Configure the L2NAT service named B-Subnet on switch SW-B according to the switch configuration table (Part 2).
en
conf t
l2nat instance B-Subnet
inside from network 192.168.1.0 to 10.1.1.32 mask
255.255.255.240
outside from host 10.1.1.254 to 192.168.1.254 outside from network 10.1.1.32 to 192.168.1.0 mask
255.255.255.240
outside from network 10.1.1.16 to 192.168.1.16 mask
255.255.255.240
Step 6 . Assign the B-Subnet instance to an interface on switch SW-B. interface Gi1/1
l2nat B-Subnet
Step 7 . Check that PC-A1 PC-B1, PC-A2 PC-B2, PC-A3 PC-B3, can ping each other.
