Specifications

Virtual servers
BIG-IP® Reference Guide 4-71
creating VLAN groups and assigning self IP addresses to them, see
Chapter 3, Creating VLAN groups, on page 3-14. For information on
disabling a virtual server for a specific VLAN, see Enabling or disabling a
virtual server, on page 4-84.
Wildcard virtual servers
Wildcard virtual servers are a special type of virtual server designed to
manage network traffic for transparent network devices, such as transparent
firewalls, routers, proxy servers, or cache servers. A wildcard virtual server
manages network traffic that has a destination IP address unknown to the
BIG-IP. A standard virtual server typically represents a specific site, such as
an Internet web site, and its IP address matches the IP address that DNS
associates with the site’s domain name. When the BIG-IP receives a
connection request for that site, the BIG-IP recognizes that the client’s
destination IP address matches the IP address of the virtual server, and it
subsequently forwards the client to one of the content servers that the virtual
server load balances.
However, when you are load balancing transparent nodes, a client’s
destination IP address is going to seem random. The client is connecting to
an IP address on the other side of the firewall, router, or proxy server. In this
situation, the BIG-IP cannot match the client’s destination IP address to a
virtual server IP address. Wildcard virtual servers resolve this problem by
not translating the incoming IP address at the virtual server level on the
BIG-IP. For example, when the BIG-IP does not find a specific virtual
server match for a client’s destination IP address, it matches the client’s
destination IP address to a wildcard virtual server. The BIG-IP then
forwards the client’s packet to one of the firewalls or routers that the
wildcard virtual server load balances, which in turn forwards the client’s
packet to the actual destination IP address.
Default vs. port-specific wildcard servers
When you configure wildcard virtual servers and the nodes that they load
balance, you can use a wildcard port (port 0) in place of a real port number
or service name. A wildcard port handles any and all types of network
services.
A wildcard virtual server that uses port 0 is referred to as a default wildcard
virtual server, and it handles traffic for all services. A port-specific wildcard
virtual server handles traffic only for a particular service, and you define it
using a service name or a port number. If you use both a default wildcard
virtual server and port-specific wildcard virtual servers, any traffic that does
not match either a standard virtual server or one of the port-specific
wildcard virtual servers is handled by the default wildcard virtual server.
By default, a default wildcard virtual server is enabled for all VLANs.
However, you can specifically disable any VLANs that you do not want the
default wildcard virtual server to support. Disabling VLANs for the default
wildcard virtual server is done by creating a VLAN disabled list. Note that a