Tag Archives: VLAN

Enhanced Routing and QOS Models using Software Defined Networking

Quality of service implementations that utilize Integrated Services (IntServ) provides end-to-end service guarantees to IP traffic traversing campus networks. IntServ allows applications to signal their QOS requirements to the network while providing strong guarantees to individual traffic flows from sender to receiver,however IntServ quality of service architectures require all routers to implement a reservation protocol and maintain state information for all flows.

Computation of routes and the maintenance of states requires copious amounts of RAM and Processing power in order to scale to support large route and flow tables. Routers and switches built on merchant Asic are typically equipped with a limited  amounts of ram and processing power when compared to the typical X86 computer. The price of multi-core CPUs and DDR memory modules are at an all time low and this reality should allow the development of  a x86 based SDN controller that will be able to incrementally store router flow and link states.


SNMP or NETFLOW could be used to measure various constraints such as bandwidth,latency and delay. The values measured could be used to perform constrained shortest path route calculations for each node and also to modify route or congestion management characteristics on a per interface basis. 


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Posted by on August 7, 2013 in Uncategorized


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Building a Vmware Powered Hybrid Cloud using Ecalyptus

The Cloud means many things to many different persons,but personally I view a Cloud as a distinct pool of  computing resources that can be manage centrally, provides the ability to scale resources via pre configured policies and lastly provides the ability to automate manual requests such as Virtual Machine creation and deployment.

Though not recommended by many IT professionals, I am planning on making our IT department an internal service provider. In this vain it is my vision to build out a Private Cloud that can provide self service to authorized internal clients such as our developers and application administrators.Currently we utilize a Vmware Vsphere platform, but in another few months this platform will possess all the attributes of a true cloud.To provide the functions necessary I have decided that we will look at the Open Source Eucalyptus platform.

Eucalyptus is Open Source so it reduces our initial capital expenditure ,it is compatible with Vmware and it has the ability to support Amazon based workloads thus providing a Hybrid platform mangement tool.

At Stage one, we will roll out a Private Cloud  that will allow authorized internal clients to perform various tasks related to a an assigned blocked of computing resources.

At Stage two we will seek to allow the migration of workloads between Amazon and our Vmware based private cloud,this should provide Disaster recovery and scalability benefits to our group.


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Posted by on December 5, 2012 in Technology


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Open Source Unified Communications

Unified Communications or UC is ruled by the Cisco,Microsoft and Avaya. All three companies are developers of great UC software suites but come in at prices that may be out of range  for small and medium sized companies. Now i am huge proponent of cutting costs when possible and as such my advice to small companies is to evaluate Open Source UC tools when looking for a new solution to replace your PBX systems.

The state of affairs in the Open Unified Communications market is as follows. The most popular Open Source UC package would be asterisk but it also a little harder to manage than alternative packages. For a small shop with less than 100 phones my recommendation would be Fonality’s Trixbox. Trixbox has a commercial and community edition which is backed by a large user base. Trixbox’s major drawback is its inability to scale for large installs but this is not an issue for a small company.

The best Open Source UC package for Small and Medium size companies is sipXecs. SIPX is totally sip based and was built to scale up to 1000 users. Unlike asterisks which switches voice streams and was built to sit between endpoints, SIPX functions as a sip proxy and does not require endpoints to pass voice data through the SIPX server, it is this fact that allows SIPX to scale better than asterisks.While not as extensible as asterisks SIPX represents a great option for medium sized companies looking to jump into the UC world and at this moments represents the top of the open source UC pile.


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Posted by on November 17, 2012 in Uncategorized


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Large Layer 2 Domains and Vmotion

Vmware V-motion requires physical hosts to be in the same layer two domain. This goes against the grain in networks that were built around the principle of reducing the size and reach of broadcast domains.Layer 2 broadcast domains reduces the bandwidth available to our applications due to effect of frame flooding and also because Spanning tree’s operation disables redundant paths in our layer 2 networks.

Vmotion’s layer 2 requirement may be one of major reason why Flat layer 2 networks are being optimized.These optimization’s mitigate against the effects of broadcasts and unknown Unicast flooding which wastes network bandwidth.TRILL which is not really necessary to support Vmotion, has been developed to replace spanning tree in bandwidth intensive use cases that need all links to be forwarding at once. The existence of applications that require huge Flat networks will ensure the continued evolution of the layer 2 switching space and thus augment the simple plug N play nature of Ethernet networks that most people appreciate.








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Posted by on September 20, 2012 in Technology


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Successor based Flow Failover in Open Flow Networks

The failure of links in software defined networks based on Open Flow will result in the need to converge on a new topology which will be the same at layer 2 or 3 since open flow seems to merge the control and data planes resulting in unified logical topologies. Since Open Flow utilizes flow tables the concept of feasible successors can be applied to flow tables by inserting alternate paths as less preferred flow entries. The use of successor routes will result in no need to contact a controller on link failures.

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Posted by on July 16, 2012 in Technology


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My Software Defined Networking Wishlist

The primary goal i would be seeking to meet when i decide to implement Open Flow or some other SDN framework is management simplicity.Below i have listed two things that i hope SDN will address when it becomes main stream in enterprises.

Automatic VLAN Grafting

Connectivity issues resulting from the absence of Vlans on trunk links is a common problem that network techs face when provisioning access ports.SDN can be really valuable if it is able to graft vlans to trunk links based on learnt layer two traffic flow.

Advanced Optimized Edge Routing that integrates QOS

Currently OER/PFR is unable to implement QOS policy decisions on flows that are not operating within a certain threshold. An OPEN FLOW controller that implements QOS policies while managing policies below edge devices such as those in the network core would greatly enhance policy based routing design and overall network architecture design.

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Posted by on June 23, 2012 in Technology


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The Cisco Supervisor 2T Long live the King


For those of us who manage networks with Cisco 6500 series switches in their core, I am sure the wide array of high bandwidth switches from Cisco and their competitors have caught your attention. The 6500 series provides 10GB performance at 80Gig per slot when coupled with supervisor 2T modules. The question you should be asking ,is how much throughput do I need in the future?. If your bandwidth needs are growing exponentially and you want to have data center traffic traverse your core switches then upgrading your 6500 switch might not be a such a good idea since data center and its aggregated bandwidth demands can be significant in a medium to large organization.

However the drawback to acquiring new switches relate to their price, a Supervisor Upgrade would be much cheaper than acquiring a similar sized switch. Size though also  does not truly reflect the state of affairs since they are now 2U sized switches that  are able to out perform an upgraded 6509, example of such a devices can be found in the Nexus 5000 series switching line. If you run separate data center and user networks (as you should) then a 6509 with a supervisor 2T module results in a  relatively inexpensive upgrade that will cause only minor disruptions and results in less headache at 3x your current performance. Upgrading your switch using a smaller unit will always pose challenges as it relate to re-cabling and re-arrangement of your core network which is always daunting due to the differences in the number of switch ports. Sometimes we need to stay put until we have a clear need for change, so if you are not oversubscribing your current infrastructure but want to future proof it then the supervisor 2T provides reasonable investment protection.

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Posted by on April 21, 2012 in Technology


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