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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Looking at Dell Force 10

Dell has hit a home run with their force10 line. Born in the world of high frequency trading, Force10 with its huge output buffer provides Dow Jones, twitter and Facebook with low latency switching infrastructures. At prices lower than the nexus line and providing a command line that is syntactically similar to Cisco’s IOS. Force10 represent bridge to a hybrid network where Cisco IOS and force10 FTOS in concert with open standards such as lldp and gvrp gives the enterprise the ability to ensure that we receive the best features at the lowest pricepoints.

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Posted by on September 14, 2012 in Technology


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Multicast Application Design

Multicast is used to distribute data from one source to many receivers.These receivers normally are executing an application which in its underlying logic has joined a multicast group which is essentially a ip address that is able represent multiple nodes on a network. Public multicast ip addresses are rarely available to network managers or application dev teams hence applications should be developed to accept multicast ip address and port information in its initializtion code. This approach allows an application to be ip address agnostic and and allows the app to join any available multicast address

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Posted by on August 29, 2012 in Uncategorized


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Nexus 7000 Virtual Data Centers

Virtual data centers allows enterprises and Service providers to create truly distinct DCs that overlay a single physical infrastructure.The Cisco nexus provides the ability to virtualize all three planes namely the control,forwarding and management planes. For enterprises the ability to create logical virtual networks for testing purposes can provide significant cost savings since the need to buy test equipment is eliminated.

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Posted by on August 6, 2012 in Uncategorized


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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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Multi Tenant data centers being used to provide cloud services has led to a number of network requirements that are difficult to meet using VRF, Q-In-Q or other tunneling techniques.A Cloud data center customer needs to be able to provision network resources such as virtual switches and RFC 1918 IP addresses  without needing to consider similar resources being used by other tenants. Software Defined networking seeks to provide an END-to-END virtual network that consists of virtual forwarding tables ,virtual routers,virtual switches and controllers.  Software Defined Networking can be used to create logical networks that consist of virtual network gear. SDN tracks the state of the underlying physical data center network along with the overlaying virtual networks.

State changes are recorded and the Physical or Logical components affected by these said state changes are configured to have their settings and operations updated to support the changes made by the data center’s customer. Software defined networking’s ability to provide distributed,rule driven control of large physical network elements presents a new way of virtualizing network resources.


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Posted by on June 13, 2012 in Uncategorized


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