Specifications

LSNAT Overview
September 8, 2010 Page 4 of 28
LSNAT Overview
ThissectionprovidesanoverviewoftheLSNATcomponents.
TheLSNATconfigurationismadeupofoneormoreserverfarms,eachcontainingmultiplereal
serversthatfacetheclientthroughaconfiguredvirtualserver.AllaspectsofanLSNAT
configurationrelatetotheconfigurationormanagementofoneofthese
threeLSNATcomponents:
serverfarm,realserver,andvirtualserver.
Figure 2onpage 5presentsanLSNATpacketflow.Arequestforservicesissentbytheclientto
theVirtualserverIPaddress(VIP)ontheLSNATconfiguredrouter.Thesourceaddressforthis
requestistheclientIPaddress.The
destinationaddressfortherequestistheLSNATconfigured
VIPaddress.TheLSNATconfiguredrouterrecognizestheVIPaddressandbasedupontheserver
loadbalancingprocessconfigured(roundrobinisdisplayed)LSNATchangesthedestination
addressfromtheVIPaddresstotheaddressofoneoftherealserver
membersoftheserverfarm
associatedwiththeVIPaddress.Thepacketisforwardedtotheselectedrealserver.
Whentherealserversendsaresponsebacktotheclient,LSNATseestherealserveraddressand
translatesitbacktotheVIPaddressbeforeforwardingthepacketontothe
client.
Notes: LSNAT is currently supported on the Enterasys S-Series and N-Series products. This
document details the configuration of LSNAT for these products.
LSNAT is an advanced routing feature that must be enabled with a license key on the N-Series
router. An advanced routing license is currently not required on the S-Series platform. If you have
purchased an advanced license key, and have enabled routing on the device, you must activate
your license as described in the configuration guide that comes with your Enterasys N-Series
product in order to enable the LSNAT command set. If you wish to purchase an advanced routing
license, contact Enterasys Networks Sales.
A minimum of 256 MB of memory is required on all modules in order to enable LSNAT. See the
SDRAM field of the show system hardware command to display the amount of memory installed
on a module. An N-Series module memory can be upgraded to 256 MB using the DFE-256MB-UGK
memory kit.