A self IP address
is an IP address on the BIG-IP®
system that you associate with a VLAN, to access hosts in that VLAN. By virtue of its netmask, a self IP address represents an address space
, that is, a range of IP addresses spanning the hosts in the VLAN, rather than a single host address. You can associate self IP addresses not only with VLANs, but also with VLAN groups.
Self IP addresses serve two purposes. First, when sending a message to a
destination server, the BIG-IP system uses the self IP addresses of its VLANs to determine the specific VLAN in which a destination server resides. For example, if VLAN internal
has a self IP address of 10.10.10.100
, with a netmask of 255.255.255.0
, and the destination servers IP address is 10.10.10.20
(with a netmask of 255.255.255.255
), the BIG-IP system recognizes that the servers IP address falls within the range of VLAN internal
s self IP address, and therefore sends the message to that VLAN. More specifically, the BIG-IP system sends the message to the interface that you assigned to that VLAN. If more than one interface is assigned to the VLAN, the BIG-IP system takes additional steps to determine the correct interface, such as checking the layer2 forwarding table.
Second, a self IP address serves as the default route for each destination
server in the corresponding VLAN. In this case, the self IP address of a VLAN appears as the destination IP address in the packet header when the server sends a response to the BIG-IP system. For more information on configuring the default route of a destination server, see Chapter 14, Configuring High Availability
You normally assign self IP addresses to a VLAN when you initially run the
Setup utility on a BIG-IP system. More specifically, you assign one static self IP address and one floating self IP address to each of the default VLANs (internal
). Later, using the Configuration utility, you can create self IP addresses for other VLANs that you create.
| || |A static self IP address
is an IP address that the BIG-IP system does not share with another BIG-IP system. By default, the self IP addresses that you create with the Configuration utility are static self IP addresses.
| || |A floating self IP address
is an IP address that two BIG-IP systems share, such as two units of a redundant system. When you use the Configuration utility to create a self IP address, you can specify that you want the IP address to be a floating address.
For each self IP address that you create for a VLAN, the BIG-IP system
automatically assigns a media access control (MAC) address. By default, the BIG-IP system assigns the same MAC address that is assigned to the lowest-numbered interface of the VLAN.
As an alternative, you can globally configure the BIG-IP system to assign
the same MAC address to all VLANs. This feature is useful if your network includes a type of switch that does not keep a separate Layer 2 forwarding table for each VLAN on that switch.
When you configure the BIG-IP system to manage local area traffic, you can
implement a feature known as a secure network address translation (SNAT). A SNAT
is an object that causes the BIG-IP system to translate the original source IP address of a packet to an IP address that you specify. A SNAT ensures that the target server sends its response back through the BIG-IP system rather than to the original client IP address directly.
When you create a SNAT, you can configure the BIG-IP system to
automatically choose a translation address. This ability of the BIG-IP system to automatically choose a translation address is known as SNAT automapping
, and in this case, the translation address that the system chooses is always an existing self IP address. Thus, for traffic going from the BIG-IP system to a destination server, configuring SNAT automapping ensures that the source IP address in the header of a packet is a self IP address.
When you create an automapped SNAT, the BIG-IP system actually creates
a SNAT pool consisting of the systems internal self IP addresses, and then uses an algorithm to select and assign an address from that SNAT pool.
For more information on SNAT automapping, see the Configuration Guide for BIG-IP® Local Traffic Management
As stated previously, it is when you initially run the Setup utility on a
BIG-IP system that you normally create any static and floating self IP addresses and assign them to VLANs. However, if you want to create additional self IP addresses later, you can do so using the Configuration utility.
Use the following procedure to create a self IP address. For detailed
information about each setting, see the sections following the procedure.
If the Create
button is unavailable, you do not have permission to create a self IP address. You must have either the Administrator
or Resource Manager
role assigned to your user account.
| |In the IP Address
box, type the self IP address that you want to assign to a VLAN.
| |In the Netmask
box, type a netmask.
| |For the VLAN
setting, select the name of the VLAN to which you want to assign the self IP address.
The default value is internal
| |For the Port Lockdown
setting, select Allow Default
, Allow All
, Allow None
, or Allow Custom
Selecting Allow Custom
displays the Custom List
setting. For more information on these setting values, see Specifying port lockdown
| |If you chose Allow Custom
in step 7, click TCP
, or Protocol
and then click Add
The value All
appears in the TCP
, type a port number, and then click Add
The port number appears in the TCP
| |If you chose Protocol
, select a protocol name and click Add
As described in Introducing self IP addresses
, a self IP address, combined with a netmask, typically represents a range of host IP addresses in a VLAN. If you are assigning a self IP address to a VLAN group, the self IP address represents the range of self IP addresses assigned to the VLANs in that group.
The self IP address that you specify in the IP Address
setting is a static IP address, unless you enable the Floating IP
setting. For more information, see Specifying a floating IP address
When you specify a netmask for a self IP address, the self IP address can
represent a range of IP addresses, rather than a single host address. For example, a self IP address of 10.0.0.100
can represent several host IP addresses if you specify a netmask of 255.255.0.0
| || |Assigning a self IP address to a VLAN
The self IP address that you assign to a VLAN should represent an address space that includes the self IP addresses of the hosts that the VLAN contains. For example, if the address of one destination server in a VLAN is 10.0.0.1
and the address of another server in the VLAN is 10.0.0.2
, you could assign a self IP address of 10.0.0.100
, with a netmask of 255.255.0.0
, to the VLAN.
| || |Assigning a self IP address to a VLAN group
The self IP address that you assign to a VLAN group should represent an address space that includes the self IP addresses of the VLANs that you assigned to the group. For example, if the self IP address of one VLAN in a VLAN group is 10.0.20.100
and the address of the other VLAN in a VLAN group is 10.0.30.100
,you could assign an address of 10.0.0.100
, with a netmask of 255.255.0.0
, to the VLAN group.
list displays the names of all existing VLANs and VLAN groups.
Each self IP address has a feature known as port lockdown. Port lockdown
is a security feature that allows you to specify particular UDP and TCP protocols and services from which the self IP address can accept traffic. By default, a self IP address accepts traffic from these protocols and services:
If you do not want to use the default setting (Allow Default
), you can configure port lockdown to allow either all UDP and TCP protocols and services (Allow All
), no UDP protocols and services (Allow None
), or only those that you specify (Allow Custom
You can enable the Floating IP
setting if you want the self IP address to be a floating IP address, that is, an address shared between two BIG-IP systems. A floating self IP address enables a destination server to successfully send a response when the relevant BIG-IP unit is unavailable. When two units share a floating self IP address, a destination server can send traffic to that address instead of a static self IP address. If the target unit is unavailable, the peer unit can receive and process that traffic. Without this shared floating IP address, the delivery of server traffic to a unit of a redundant system can fail.
Note: The Floating IP
setting appears on the screen only when the BIG-IP system is configured as a unit of a redundant system. For more information on configuring a redundant system, see Chapter 14, Configuring High Availability
| |Click Delete
A confirmation screen appears.