What are the different types of Virtual Servers used in F5 Load Balancer?

1) Standard Virtual Server

--> BIG IP F5 LTM acts as Full Proxy for all the connections in Standard Virtual Server type.

--> A Standard virtual server directs client traffic to a load balancing pool.

--> A Standard virtual server is the most basic type of virtual server used in F5 LTM.

--> The Standard virtual server requires a TCP or UDP profile in F5 LTM.

--> The Standard virtual server may optionally be configured with HTTP, FTP, or SSL profiles if Layer 7 or SSL processing is required.

-->  The client must send at least one data packet before the server-side connection can be initiated by the BIG-IP LTM system, if a Standard virtual server is configured with Layer 7 functionality, such as an HTTP profile.

2) Performance Layer 4 Virtual Server

--> Performance Layer 4 Virtual Server has a fast layer 4 profile.

--> Big IP F5 LTM processes the information packet by packet basis.

--> The virtual server and profile increase the speed at which the virtual server processes Layer 4 requests.

--> It does not follow full proxy architecture as Standard Virtual Server.

3) Performance HTTP Virtual Server

--> By default, fast HTTP profile is associated with Performance HTTP Virtual Server.

--> Performance HTTP Virtual Server of two types, i) No IDLE Server Side flow ii) IDLE Server Side flow

i) No IDLE Server Side flow: TCP Connection to the pool member will be established only after the client has established TCP 3-way handshake with f5 LTM.

ii) IDLE Server Side flow: TCP Connection to the pool member will be established before the client has established TCP 3-way handshake with f5 LTM.

4) Forwarding (IP)

--> A Forwarding (IP) virtual server is similar to other virtual servers, except that a forwarding virtual server has no pool members to load balance.

--> The virtual server simply forwards the packet directly to the destination IP address specified in the client request.

--> When you use a forwarding virtual server to direct a request to its originally-specified destination IP address, Local Traffic Manager adds, tracks, and reaps these connections just as with other virtual servers.

--> You can also view statistics for a forwarding virtual servers.

5) Forwarding ( Layer 2)

--> We need to create VLAN Group in F5 LTM and assign an IP address to it, for forwarding layer 2 virtual server.

--> Forwarding (Layer 2) virtual server shares the same IP address as a node in an associated VLAN.

--> LTM Processes the packets to the destination server based upon destination MAC Address.

--> Does not follow full proxy architecture.

6) Reject

--> A Reject virtual server rejects any traffic destined for the virtual server IP address.

--> Whenever any SYN Packet comes on reject virtual server by sending the reset packet to it.

7) Stateless

--> A stateless virtual server prevents the BIG-IP system from putting connections into the connection table for wildcard and forwarding destination IP addresses.

-->  When creating a stateless virtual server, you cannot configure SNAT automap, iRules, or port translation, and you must configure a default load balancing pool.

--> Note that this type of virtual server applies to UDP traffic only.

Ref: F5

Md.Kareemoddin

CCIE # 54759