As inter Data Center communication is now a focus, especially with
VM2VM2VM (Virtual Machine) communication between intra / inter LAN segments there is now
a strong requirements for Layer 2 interconnections, e.g. tunneling L2 with L3 connection.
Stretching Layer 2 domains between sites whilst achievable using Spanning-Tree has
many disadvantages. Any broadcast flooding or spanning-tree flaps within
one Data Center will propagate across to the other data centre. Transparent Interconnection
of Lots of Links (TRILL), an IETF standard, is one approach that brings about an improvement with the traditional Spanning Tree Tables approach. This increases the flexibility as “redundant links” can be used in an intelligent way. Look at TRILL as a next generation Spanning Tree Tables.
VXLAN – Virtual Extensible LAN – is a method of encapsulating L2 Ethernet frame within UDP with 50bytes of overhead. These encapsulated frames are “tunnelled” between the VEM’s (Virtual Ethernet Modules) attached to the VM(s).
This allows VMs to communicate as if they belong to the same subnet.
Traditionally an IP address is used to describe a devices
Identity (ID) but also it’s location. If you move a device to a
different site then you must change it’s IP in order to match it’s new location.
LISP – Location ID/Separation protocol – attempts to separate the location
and ID so that a device can change location whilst keeping the same identity.
The above (TRILL, VXLAN and LISP) will help organisations to create MSDCs by supporting
L2/L3 tunneling, movement of devices in a flexible way and supporting seamless VM2VM communication.
VBR/ Wallis Dudhnath