We have received a note concerning stateful failover of the CSS series of products, where the CSS 110XX series doesn't support stateful failover, however the CSS 115XXX will. Here is the digest of the message;
On 3/6, Hosting Engineering and Operations issued an alert regarding the
CSS 11000 load balancer. This is an update to that alert.
Since that time, we have experienced another hardware failure of this
model device.
In response to this situation, the following has occured:
* Platform Engineeringis in the process of removing the CSS 11000
from the SOE. Itis on target to be removed in April.
* Operations hasre-inforced our escalation procedures with CISCO.
Qwest is to beissued a RMA immediately for this model.
* For newconfigurations including a CSS 11000, CCAR will require
an Individual CaseBasis (ICB) review and approval.
* For existing premiumand above customers whoes configurations
include a CSS 11000, HostingOperations is planning to replace them with
compatible device. These changes have been pre-approved by CCAR as long
as:
* the networktopology remains the same
* redundancy ispreserved
* CCAR gets notifiedof the replacement model so we can update our
records
* For existing basicand enhanced customers, we are drafting a
communique that alerts them tothe performance issues exerienced by Qwest
and providing suggestedalternative solutions.
In response to recent questions from the field.....
Stateful failover with redundant CSS 11000 Series Load Balancers:
The Bottom Line: Cisco CSS 11000 Series Load Balancers do not support
stateful
failover.
Will Cisco ever support this?: Yes, this is supported in the CSS 11500
Series,
known as Adaptive Session Redundancy (ASR)
I need this today, what can I do?: Choose an alternative product. The
F5 BIG-IP
load balancers support this functionality.
What is stateful failover anyhow?
Stateful failover is a technology that can maintain state information
between
the active load-balancer and the standby load-balancer. This state
information
can include: persistence mapping, telnet sessions, ftp sessions, tcp
session
state, etc...
Why should I be concerned?
Without state synchronization applications can break if there is a
failover from
the active to standby unit. FTP Sessions will be broken, Telnet
sessions will
be broken, and most importantly persistence state mapping will be lost.
What do I need to listen for to determine if stateful failover is
important?
1. E-commerce applications that require persistence mapping.
Persistence
mapping will keep a client session mapped to the same server for a
specified
amount of time. This is often important with shopping cart and other
e-commerce
applications.
2. Long-lived sessions. Whether they are planning to transfer large
files via
FTP or long-lived telnet sessions. Anytime a connection will be
required for a
long time and starting over is not an acceptable condition, then
stateful
failover is important.
Does this sound correct or is this a bunch of hot air?
