Re: [load balancing] Problem in pop3 connection

From: Manish Verma (
Date: Wed Jan 21 2004 - 23:58:37 EST

  • Next message: simon bullen: "Re: [load balancing] Problem in pop3 connection"

    Hi ,

    I am using Alteon AD3 , I am facing the problem establishing the POP
    connection on slow links .When ever i access POP on Slow link i always get
    the error:

    : Your server has unexpectedly terminated the connection. Possible causes
    for this include server problems, network problems, or a long period of
    inactivity. Subject '', Account: Server: , Protocol: SMTP, Port: 25,
    Secure(SSL): No, Socket Error: 10054, Error

    If this is the known problem pl let me know what all settings could be done
    on the alteon to resolve the problem.


    ----- Original Message -----
    From: "Shawn Nunley" <>
    To: <>
    Sent: Thursday, January 22, 2004 7:40 AM
    Subject: RE: [load balancing] Load Balancer Evaluation: Which would you

    > John,
    > Just to be clear, the NetScaler device does not ever send connections
    > 'through' ANY OS, ever. The performance effects of doing this would be
    > catastrophic and would not allow us to support the speeds and feeds we
    > advertise. Everything is handled within our packet engine which
    > communicates directly with RAM, NICs and the CPU, all in kernel mode with
    > context switching to slow things down.
    > The difference is worth pointing out since we spent years developing that
    > technology in order *not* to be lumped in with devices that are limited by
    > generic OS TCP/IP stacks. Nothing personal, but I couldn't let that
    > generalization just slip by.
    > BTW, I hope you're having a great New Year.
    > -Shawn
    > -----Original Message-----
    > From: John Hall []
    > Sent: Wednesday, January 21, 2004 12:44 PM
    > To:
    > Subject: Re: [load balancing] Load Balancer Evaluation: Which would you
    > pick?
    > It would be interesting to find out what engineer said this, but it is
    > essentially incorrect. Recent BIG-IP's that have our Packet Velocity
    > ASIC (you gotta love marketing folks) have a range of load balancing
    > options including full hardware acceleration (the entire connection is
    > handled by the ASIC with no host processor support required) through
    > partial acceleration (the connection is initially handled by software,
    > but as soon as a load balancing decision is made, it's handed off to the
    > ASIC for the rest of the connection), to full software load balancing
    > which provides all the possible load balancing capabilities.
    > In regards to the original question. I strongly suggest that you ask
    > the top several vendors on your list specifc questions about your
    > planned (and future) load profile. All of the boxes you are looking at
    > have a host processor running some OS (vxWorks, BSD, BSDI, etc) and all
    > of them send some types of connections to the host processor for
    > handling. The loads you are planning are significantly above the
    > capabilities of some of the boxes you list to handle in software, but
    > are probably quite easily handled in a partially or fully hardware
    > accelerated modes. Specific characterization of your load profile and
    > some direct questions to the vendors should help you narrow down your
    > choices.
    > An illustrative anecdote involves the effect of the Nachi worm on
    > several vendors of six-figure cost layer 2/3 switches. Many of the
    > vendors sent ICMP packets to the switches host processor for handling
    > and their host processors are often amazingly low powered, so a single
    > Nachi infected PC sending ICMP packets to thousands of random
    > destinations could bring these very expensive and capable switches to
    > their knees. Some switches handled ICMP in hardware, but updated their
    > ARP tables using the host processor and they were incapacitated by ARP
    > updates. So, while these switches quite ably handled the "normal" layer
    > 2/3 load, they were crippled by an unusual (but perfectly "legal", at
    > least according to the RFC's) load profile that their designers did not
    > anticipate.
    > JMH
    > Mike W wrote:
    > > Radware is a switch based solution, while F5 is still a unix kernel
    > > based product, which some say takes them out of the "switch market" -
    > > their marketing discusses their network processor, but one of there
    > > engineers at a trade show last year finally admitted when pressed,
    > > that they didn't use it when doing actual load balancing, only if they
    > > were a router.
    > --
    > John Hall Test Manager - Switch Team F5 Networks,
    > Inc.
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