RE: [load balancing] Alteon returns server IP to customer

From: Shahar Hershkovich (shaharIZZATxor.co.il)
Date: Wed Feb 13 2002 - 18:20:30 EST

  • Next message: Hĺkan Lindholm: "[load balancing] Alteon OID for VIP b/w?"

    I want to thank everyone for the quick responses.
    The fastage and slowage feature fixed my problem.

    Thanks.

    At 01:15 13/02/2002, you wrote:

    >Possible, but not likely. BTW, please see <http://www.securityfocus.com/archive/1/254995>http://www.securityfocus.com/archive/1/254995.
    >
    >Assuming a correct configuration and topology, the probable cause is the session is getting removed from the session table before the server is finished. By default the switch will remove a session table entry within 2-4 seconds upon receipt of a FIN from the client or server. A quick test for this would be to set the "/cfg/slb/adv/fastage 1". This will tell the switch to fastage the session from the table in 4-8 seconds, giving enough time for all the packets in the TCP session to pass through the switch before the session is removed. If you continue to see RIP leakage, but to a lesser extent, increase fastage to 2 (8-16 seconds). That should take care of most instances of RIP leakage.
    >
    >Increasing fastage can increase the number of concurrent sessions on the switch. Monitor the session count before and after adjusting fastage.
    >
    >With regard to the bugtraq posting. As a workaround, RIP leakage can be blocked at an upstream FW as Shahar is doing, or blocked on the Alteon's server ports by applying deny filters. VMA should be enabled (/cfg/slb/adv/ma en) and the filter should have a SIP=RIP and SPORT=RPORT with action deny. Server processing occurs before filter processing when VMA is enabled, so don't worry, you won't be denying legitimate traffic from your server farm.
    >
    >If you require further assistance, please open a case with Nortel Support at 1-800-4NORTEL, Express Routing Code 343.
    >
    >Hope this helps... Peter
    >
    >-----Original Message-----
    >From: pewi [<mailto:pewisch1IZZATgmx.ch>mailto:pewisch1IZZATgmx.ch]
    >Sent: Tuesday, February 12, 2002 4:05 PM
    >To: lb-lIZZATvegan.net
    >Subject: AW: [load balancing] Alteon returns server IP to customer
    >
    >Hi,
    >
    >read this info on securityfocus ( <http://www.securityfocus.com/bid/3964>http://www.securityfocus.com/bid/3964 ) it
    >sounds like your problem.
    >
    >pe
    >
    >-----Ursprüngliche Nachricht-----
    >Von: owner-lb-lIZZATvegan.net [<mailto:owner-lb-lIZZATvegan.net>mailto:owner-lb-lIZZATvegan.net]Im Auftrag von
    >Daniel Peterson
    >Gesendet: Dienstag, 12. Februar 2002 18:30
    >An: lb-lIZZATvegan.net
    >Betreff: Re: [load balancing] Alteon returns server IP to customer
    >
    >Greetings,
    >
    >Make sure layer3 load balancing is disabled. If I
    >remember right there are some /cfg/slb/fastage and
    >/cfg/slb/slowage settings that can be adjusted in case
    >this situation is occurring.
    >
    >I think Peter Degrassi is the best person to refer
    >this to. He was always the most knowledgable person
    >I've dealt with at Alteon. I've seen him reply to
    >some quesitons on this list.
    >
    >Good luck,
    >
    >Dan
    >
    >--- Gonzalo_Julián_Bécares_Fernández <gonzaloIZZATya.com>
    >wrote:
    >>
    >> Sorry for my first answered.... I have read too
    >> fast your mail......
    >>
    >> We have 6 alteon with 8.3 and 9.0 webos, and we
    >> haven´t detected that
    >> problem.
    >>
    >>
    >> Regards.
    >>
    >>
    >>
    >>
    >>
    >> ----- Original Message -----
    >> From: "Gonzalo Julián Bécares Fernández"
    >> <gonzaloIZZATya.com>
    >> To: <lb-lIZZATvegan.net>
    >> Sent: Tuesday, February 12, 2002 12:47 PM
    >> Subject: Re: [load balancing] Alteon returns server
    >> IP to customer
    >>
    >>
    >> >
    >> > Hi,
    >> >
    >> > you must configure the alteon port (or trunk
    >> ports) where vip go out
    >> as
    >> > client, and the alteon port where the servers are
    >> connected as server
    >> (i.e.
    >> > /cfg/slb/port 1/server or /cfg/slb/port 2/client).
    >> >
    >> > Regards.
    >> >
    >> > Gonzalo Bécares.
    >> > Ya.com Internet Factory
    >> >
    >> >
    >> >
    >> > ----- Original Message -----
    >> > From: "Shahar Hershkovich" <shaharIZZATxor.co.il>
    >> > To: <lb-lIZZATvegan.net>
    >> > Sent: Tuesday, February 12, 2002 11:38 AM
    >> > Subject: [load balancing] Alteon returns server IP
    >> to customer
    >> >
    >> >
    >> > > Hi all.
    >> > >
    >> > > I have a strange issue with an AD3 Alteon.
    >> > > Once in a while it starts sending the response
    >> from the web servers
    >> > without replacing the source IP address to the VIP
    >> address. The firewall
    >> > then drops the packed seeing a response for a
    >> connection that doesn't
    >> > exists.
    >> > > I thought that maybe it's a matter of the
    >> Alteon's client to server
    >> table
    >> > timed out but this is not the case (the response
    >> is too fast, a few
    >> seconds
    >> > the most).
    >> > > DAM is enabled but as I see it, it shouldn't be
    >> an issue? or is it?
    >> > >
    >> > > I'm running the Alteon with OS version 8.323.
    >> > > Any one encountered this kind of problem?
    >> > >
    >> > > Thanks.
    >> > >
    >> > > Shahar Hershkovich
    >> > > Xor Technologies
    >> > > www.xor.co.il
    >> > > +972-55-636833
    >> > >
    >> > >
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    Shahar Hershkovich
    Xor Technologies
    www.xor.co.il
    +972-55-636833

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