Load Balancers in your Network :F5- LTM and GTM

Thanks for many earlier posts for which you guys really supports us. Today i am going to touch upon one of the most interesting and never ending topic in the enterprise network. It's a kind of use case and the demands of the product in the real network environment. As per my best knowledge and learnings from the real environment i am going to share the topic on load balancers. May be i am wrong somewhere or at some point, please help to correct me and guide me on that point. So let me start with the post of load balancer which is not everyone familiar in the market now a days.

I guess the people like Network engineers, System engineers and the server guys are the appropriate audience for this post.

Load Balancers are one of the important part of the networks today, It seems that every enterprise network really looking for the load balancers in the market and ofcourse there are lot of players who actually sell Load balancers with their features and capabilities.

Now some of you guys really have a hard question, may be you are the new one in this domain of Load balancers and i knew your first question is

What is Load balancers ?
Well for your question, my answer is It's a kind of reverse proxy and distribute network or application traffic of the real environment on to the number of the servers which is deployed within the network or in the datacenter environment. This is one of the simplest answer which i gave to you. Hope it clears the basic fundamental feature of the Load balancers in the network.

Now i knew your second question, which load balancer we need to purchase ?
Well this is typical question but on the trend of the market we have many suppliers of the load balancers in the market. I am just talking about the major players in this space. These players are


  • F5 BIG-IP load balancers
  • CITRIX load balancers
  • Brocade load balancers
  • Coyote Point Systems load balancers

All other players like Cisco, Juniper and Zeus left the market as they will not compete with this much of successful players in the market.

Now your next question what is the market trend, which load balancers is first choice these days ?
Well the answer to your question is F5 BIG-IP load balancers, They made a market from the beginning and stick to it and now they are big brand in this space. The competition to F5 is hard for all other players in the market.

In which segment and in which network actually these Load balancers used ? 
Well if some one using the Facebook or if i say Indian railway website, where application is hosted on various servers so that you can manage all your users to access that application without any delay, Its load balancers who actually works behind it and send your request to one of the free servers in the domain.

So now lets talk about the F5 BIG-IP load balancers in much details. First of all we will discuss the type of load balancers in F5 BIG-IP. It has two kinds of load balancers and they are

  • F5 BIG-IP GTM ( Global traffic Manager )
  • F5 BIG-IP LTM ( Local traffic Manager )

Now we will discuss these both load balancers in details starting from GTM ( Global traffic Manager ).F5 GTM which you guys often called as Global traffic Manager distributes DNS and user application requests based on policies of business, data center and cloud environment, user location, and application based performance.

BIG-IP GTM delivers F5’s high-performance DNS Services with great visibility, inbuilt reporting, and analysis features which have hyper-scales and secures the DNS responses across the globe to survive DDoS and other attacks delivers with a complete and real-time DNSSEC solution which ensures the enterprise network with global application high availability in all hybrid and harsh environments.


Fig 1.1 F5 Load Balancers (NB)
Fig 1.1 F5 Load Balancers (NB)


There are lot of the stuff you actually doing on the internet or non-public networks begin with call decision – so it makes big experience if you’re going to load balance an software it might begin at this deposit – resolving names to IPs primarily based on availability, overall performance, and even patience.

Make a note of it that traffic does not follow via the GTM, the GTM truly tells you the first-class IP to route to primarily based on metrics for the URL in question. However generally it’s an actual server, or a digital based IP that fronts more than one servers in the network. Like a traditional DNS architecture of the network which you usually have a couple of GTMs in your architecture or the network design, this is only for redundancy and the availability.

The primary configuration element in a GTM is known as a wide IP or WIP for short.There are many configuration factors that attach in concert with a WIP, however at the bottom of it all is the extensive only the IP.

A WIP equates to the not unusual URL you’re load balancing, as an example www.networksbaseline.in . A pool or pools are commonly attached to a WIP which incorporate the IPs and it’s intelligently resolving. Like you run of the mill DNS server, the GTM does no longer inform the requester any records approximately ports. though, the monitors associated with the pool contributors can certainly reveal availability or overall performance on ports.


Fig 1.2 F5 Load Balancers (NB)
Fig 1.2 F5 Load Balancers (NB)


Unmatched DNS Performance
BIG‑IP GTM delivers DNS performance that can handle even the busiest sites in the network. When sites have a volume spike in DNS query volumes due to legitimate requests or distributed denial-of-service

 (DDoS) attacks, BIG-IP GTM manages requests with multicore processing and F5 DNS Express, dramatically increasing authoritative DNS performance to up to 20 million RPS in version 11.5 to quickly respond to all queries. This helps your organization provide the best quality of service (QoS) for your users while eliminating poor application performance. DNS Express improves standard DNS server functions by offloading DNS responses as an authoritative DNS server.

 BIG-IP GTM accepts zone transfers of DNS records from the primary DNS server and answers DNS queries authoritatively.


Benefits and features of multicore processing and DNS Express include:

• High-speed response and DDoS attack protection with in-memory DNS
• Authoritative DNS replication in multiple BIG-IP or DNS service deployments
for faster responses
• Authoritative DNS and DNSSEC in virtual clouds for disaster recovery and fast,
secure responses
• Scalable DNS performance for quality of app and service experience
• The ability to consolidate DNS servers and increase ROI

In cases of very high volumes for apps and services or a DNS DDoS attack, BIG-IP GTM hyper-scales in Rapid Response Mode (RRM) up to 40 million RPS. It extends availability with unmatched performance and security—absorbing and responding to queries at up to 200 percent of the normal limits. See page 13 for performance metrics and details.


Fig 1.3 F5 Load Balancers (NB)
Fig 1.3 F5 Load Balancers (NB)

LTM – Local Traffic Manager Overview

The Local Traffic Manager, aka LTM: is the maximum popular module provided on F5 Networks large-IP platform. The actual power of the LTM is it’s a complete Proxy, allowing you to augment consumer and server side connections.

All at the same time as making knowledgeable load balancing decisions on availability, performance, and persistence. “nearby” inside the name is essential, opposed to the GTM, traffic without a doubt flows via the LTM to the servers it balances visitors to. normally the servers it’s load balancing take a seat “domestically” within the same information center as the LTM, though that isn't a demand. With SNAT configured at the VIP, if you may course to it you could load balance it – so it’s feasible to have servers in exclusive statistics facilities be part of the equal pool in an LTM VIP.

The primary configuration detail on an LTM is the virtual IP which you always call VIP. There are lot of configuration elements that attach with VIPs, but on the big picture of the technology it’s VIP to whom they all refer to. Like a WIP, VIPs equate to the URL you are load balancing, but at its lowest level. Like a WIP it typically carries a pool with the servers and it’s load balancing & screen to degree availability and the performance.


Some of the Key differences of the GTM vs. LTM
  • The biggest difference between the GTM and LTM is the traffic actually doesn’t flow through the GTM which is going to your servers.
  • The GTM is an intelligent name resolver, intelligently resolving names to IP addresses.
  • Once the GTM provides you with an IP to route to you’re done with the GTM until you ask it to resolve another name for you.
  • Similar to a usual DNS server, the GTM does not provide any port information in its resolution.
  • The LTM doesn’t do any name resolution and assumes a DNS decision has already been made.
  • When traffic is directed to the LTM traffic flows directly through its’ full proxy architecture to the servers it’s load balancing.
  • Since the LTM is a full proxy it’s easy for it to listen on one port but direct traffic to multiple hosts listening on any port specified.
How do the GTM & LTM work together?

The GTM and LTM can work together or they can be completely impartial. in case your enterprise owns both modules it’s commonly using them collectively, and that’s where the actual electricity is available in.. They try this through a proprietary protocol referred to as iQuery.

iQuery, functioning on TCP port 4353, reviews VIP availability / overall performance again to the GTMs. The GTMs can then dynamically resolve VIPs that stay on an LTM(s).

whilst a GTM has LTMs as servers in its’ configuration there may be no want to screen the real VIP(s) with utility video display units, because the LTM is doing that & iQuery reports the records returned to the GTM.

 Please come up with your queries if you have in this article and let me know if you want the use cases on this. I am come up with the use cases for LTM and GTM in another post.
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