BROCADE IP PRIMER

Chapter 16: Session Persistence and Transparent Cache SwitchingIf you need to delete the cookie before the real server sees it, you must addthis line to the csw-policy command as well:SLB-ServerIron(config-vs-www)#match r1 rewrite delete-cookieDeleting the cookie requires the ServerIron to recalculate the full checksum ofthe data packet. This could induce some overhead that could impact performanceon your load balancer. You should use this command only whenabsolutely necessary. Again, most web applications will simply ignore a foreigncookie.Cookie HashingWith cookie hashing, you're not assigning IDs to your real servers. In fact, youchange nothing on your ServerIron's configuration (other than enabling cookiehashing). To use cookie hashing, your web servers will need to assign a cookieto the client. The ServerIron performs a checksum-like operation on the entirecookie, creating a hash value. It stores this hash value in the hash bucket,associating the hash value with that particular real server. Whenever connectionscome in, the ServerIron compares the hash value of their cookie to thehash bucket. If there's a match, the ServerIron directs the traffic to the realserver to which the hash belongs.To enable cookie hashing, you need to add the following to your virtual serverconfig:SLB-ServerIron#conf tSLB-ServerIron(config)#csw-rule r1 header "cookie" search"ServerId"SLB-ServerIron(config)#csw-policy p1SLB-ServerIron(config-csw-p1)#match r1 persist offset 0 length0SLB-ServerIron(config)#server virtual-name www 1.2.3.4SLB-ServerIron(config-vs-www)#port http csw-policy p1SLB-ServerIron(config-vs-www)#port http cswNote that this configuration is tied to the virtual server port.SSL ID Based PersistenceTo establish an SSL session, the client and server must exchange certainparameters (encryption, decryption, etc.). As part of this negotiation process,the server sends the client an SSL ID. With SSL ID Based Persistence enabledon your ServerIron, the ServerIron makes a note of this ID and ties it to the realserver that sent it. All future incoming communication for that session containsthat SSL ID. The ServerIron now always sends traffic containing a specificSSL ID to the real server that created it.To enable SSL ID Based Persistence, you need to add only one line in your virtualserver's config:SLB-ServerIron#conf tSLB-ServerIron(config)#server virtual-name www 1.2.3.4SLB-ServerIron(config-vs-www)#port sslSLB-ServerIron(config-vs-www)#port ssl session-id-switch362 Brocade IP Primer