hello could someone explain how the alteon uses the 'hash' metric to load balance. if using filters to redirect traffic to a real server group and specifiyng thash 'sip' this tells the alteon to keep the same source ip to the same real server, how does the alteon do this? thanks
There are 2 different kinds "hash" functions on Alteon. One for SLB and another one for Filter.
a. For Application Redirection, the client destination IP address is used. All requests for a specific IP destination address will be sent to the same server. This is particularly useful for maximizing successful cache hits.
b. For SLB, the client source IP address is used. All requests from a specific client will be sent to the same server. This option is useful for applications where client information must be retained between sessions.
Allows you to choose hash parameter to use for filter redirection. The Default is auto. The sip option allows you to perform tunable hash on source IP address for this filter. The option dip allows you to perform tunable hash on destination IP address for this filter. The option both allows you to perform tunable hash on both source IP address and the destination IP address at the same time. The option sip+sport allows you to perform tunable hash on both source IP address and source port at the same time.
So, Alteon uses source IP to calculate each session and redirects it to a real server. We can't know which sever will be assigned by Alteon on the first session from a client but can control every session from the same 24-bit source IP address will be redirected to the same real server as the first session.
thanku, what is exactly tunable hash? does the alteon pass the sip value of the client to the group if you have metric 'hash' specified? is the purpose so the alteon can create an index for the session (based on sip) to speed up subsuqent requests from the client with the same source ip? thanks
As I mentioned above, tunable hash for Alteon is a hash algorithm which we can change parameters in order to achieve a purpose of redirections of filters. Compare with the hash function of a real group, the parameters of tunable hash can be changed. So, it is tunable.
Alteon always keeps source IP of every packets unless you enable proxy IP function or NAT. No matter what metric you choose, Alteon never changes the source IP of every packets. It only uses source IP, destination IP, or source port to make a load balance or redirecting decision.
Yes, in your case, Alteon uses source IP to make and maintain a session table to keep load balance function properly.
Hello All ,
I am new to the world of load Balancing .Kindly help me with my doubt regarding Alteon Load Balancing using hash metric.By referring the Real Server Group configuration , I could see that the load balancing metric used is persistent hash. And by referring virtual Services Configuration, I came to know that the hash parameter used is sip.
Below is some details I got regarding Hash metric.
*The hash value is computed as follows:The load balancer computes two hash values using: The back-end server IP Address and Port (X). One of the incoming URL, Domain name, Destination IP, Source IP, Source & Destination IP, Source IP & Source Port, Call ID, Token (Y). The load balancer computes a new hash value (Z) based on (X) and (Y). The hash value (Z) is stored in cache.
The load balancer forwards the request to the server with highest hash value, by using the value (Z) from the computed hash values. Subsequent requests with the same hash value (cached) are sent to the same server.
*Can anyone just explain the end to end data flow once a new request comes???
Thanks in Advance
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