IP preserve for IPv6

IPv6 supports the IP preserve feature, which allows you to copy a configuration file from a TFTP server to multiple switches without overwriting the IPv6 address and subnet mask on VLAN 1 (the default VLAN) in each switch, and the Gateway IPv6 address assigned to the switch.

Configuring IP preserve

Enter the ip preserve statement at the end of the configuration file to be downloaded from a TFTP server. (You do not invoke IP preserve by entering a command from the CLI.)

How to enter IP preserve in a configuration file

; J9627A Configuration Editor; Created on release #xx.15.xx
hostname "HP Switch"
time daylight–time–rule None
   *
   *
   *
   *
   *
   *
password manager
password operator
ip preserve

Entering an ip preserve statement as the last line in a configuration file stored on a TFTP server allows you to download and execute the file as the startup-config file on an IPv6 switch. When the switch reboots, the configuration settings in the downloaded file are implemented without changing the IPv6 address and gateway assigned to the switch as shown in Configuration file with dedicated IP addressing.

Downloading an IP preserve configuration file to an IPv6-based switch

Enter the TFTP copy command, as described in SNMP management for IPv6, to copy the file as the new startup-config file on a switch.

When you download an IP Preserve configuration file, the following rules apply:

If the switch's current IPv6 address for VLAN 1 was statically configured and not dynamically assigned by a DHCP/Bootp server, the switch reboots and retains its current IPv6 address, subnet mask, and gateway address. All other configuration settings in the downloaded configuration file are applied.
If the switch's current IPv6 address for VLAN 1 was assigned from a DHCP server and not statically configured, IP preserve is suspended. The IPv6 addressing specified in the downloaded configuration file is implemented when the switch copies the file and reboots.
- If the downloaded file specifies DHCP/Bootp as the source for the IPv6 address of VLAN 1, the switch uses the IPv6 address assigned by the DHCP/Bootp server.
- If the file specifies a dedicated IPv6 address and subnet mask for VLAN 1 and a Gateway IPv6 address, the switch implements these settings in the startup-config file.

Verifying how IP preserve was implemented in a switch

After the switch reboots, enter the show run command. Configuration file with dedicated IP addressing shows an example in which all configurations settings have been copied into the startup-config file except for the IPv6 address of VLAN 1 (2001:db8::214:c2ff:fe4c:e480) and the default IPv6 gateway (2001:db8:0:7::5), which were retained.

If a switch received its IPv6 address from a DHCP server, the "ip address" field under "vlan 1" would display dhcp–bootp.

Configuration file with dedicated IP addressing

HP Switch(config)# show run

Running configuration:

; J8715A Configuration Editor; Created on release #xx.14.01

hostname "HP Switch"
module 1 type J8702A
module 2 type J8705A
trunk 11–12 Trk1 Trunk
ip default–gateway 

2001:db8:0:7::5
snmp–server community "public" Unrestricted
vlan 1
   name "DEFAULT_VLAN"
   untagged 1–10,13–24,1–24,Trk1
   ip address 

2001:db8::214:c2ff:fe4c:e480
exit
spanning–tree Trk1 priority 4
password manager
password operator

NOTE: Because the switch’s IPv6 address and default gateway were statically configured (not assigned by a DHCP server), when the switch boots up with the IP Preserve startup configuration file (see How to enter IP preserve in a configuration file), its current IPv6 address, subnet mask, and default gateway are not changed.

If a switch’s current IP address was acquired from a DHCP/Bootp server, the IP Preserve statement is ignored and the IP addresses in the downloaded configuration file are implemented.

For more information on how to use the IP preserve feature, see the current Basic Operation Guide .

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