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Application Delivery (ADX)

Education Series SLB LAB#1

by pmorrissey on ‎07-06-2009 09:06 PM - edited on ‎10-31-2013 03:32 PM by bcm1 (1,064 Views)

Introduction to Load Balancing and Application/Web switching - LAB#1


Configure the ServerIron to balance between the two web servers





Configuration Required:


hostname ServerIron-A

ip address

ip default-gateway



server source-ip


server real rs1

port http

port http url “HEAD /”


server real rs2

port http

port http url “HEAD /”


server virtual vip1

port http

bind http rs1 http rs2 http




Basic SLB Packet Walk – SLB Lab 1

Step 1 & 2:
Client sends request to VIP, router receives packet, ARPs for VIP, ServerIron
responds with vip-virtual-mac (02 followed by rest of port e1 MAC regardless of
which port Router is plugged into), router places that Mac address in the destination
field, places router e2 Mac into source field and forwards packet.

Step 3:
Server Iron receives packet, uses predictor to choose (in this case) server RS2 as
Dest. IP, arps for RS2’s MAC, and sends the packet out the interface where RS2
MAC lives. But, it keeps the same Source IP and (important!) same source MAC
(Router’s MAC).

Step 4:
Server RS2 receives packet. Realizes client is not on it’s subnet (, ARPs
for it’s Gateway (ServerIron source-ip). ServerIron responds with a special virtual-
MAC (02 followed by rest of port e3 MAC). RS2 then sends packet from IP destined for client IP & ServerIron virtual-MAC.

Step 5:
ServerIron receives packet, performs NAT changing Source IP to the VIP. Then,
ServerIron evaluates packet. Since, Source and Dest. IP are on different subnets, it
sends packet to it’s default gateway Re2.

Step 6:
Client receives packet returned from the IP address(VIP) it sent it’s request to.


Further Reading/Classes


For face-to-face lab time with ServerIron instructors, consider taking advantage of Brocade's introduction and advanced load balancing classes delivered by Brocade's education services. Review ETH202, ETH240 or combined ServerIron class of ETH242