Cisco 7100 Series Especificaciones descargar pdf (Pagina 78)

Step 1—Configuring Network Address Translation

Cisco 7100 Series VPN Configuration Guide

4-6

Figure 4-3 NAT Inside Source Translation

The following process describes inside source address translation, as shown in Figure 4-3:

1 The user at Host 10.1.1.1 opens a connection to Host B.

2 The ﬁrstpacket that the router receives from Host10.1.1.1 causes the router to check its

NAT table.

If a static translation entry was conﬁgured, the router goes to Step 3.

If no translation entry exists, the router determines that source address (SA) 10.1.1.1

mustbetranslateddynamically,selects a legal,global address from the dynamic address

pool, and creates a translation entry. This type of entry is called a simple entry.

3 The router replaces the inside local source address of Host 10.1.1.1 with the translation

entry’s global address, and forwards the packet.

4 Host B receives the packet and responds to Host 10.1.1.1 by using the inside global IP

destination address (DA) 10.2.2.2.

10.1.1.2

Host B

10.6.7.3

10.1.1.1

Internet

Inside

interface

Outside

interface

Outside

10.1.1.2

10.1.1.1

10.2.2.3

10.2.2.2

Inside local

IP address

NAT table

Inside global

IP address

24713

10.2.2.2

10.1.1.1

10.2.2.2

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Cisco 7100 Series Especificaciones Pagina 78