Re: VSS and PFC3A

Well Lukas,

I strongly disagree - I certainly do not recommend deploying VSS without
the 'sync-link'.
This 'sync-link' is known as VSLP dual-active fast-hello and it uses
special hello messages over a backup Ethernet connection. Dual-active
fast-hello is faster than IP BFD and does not require support from a
neighbor switch.
It is one of three mechanisms used by the virtual switching system in
order to detect a dual-active scenario if the VSL fails.
A VSL failure is important to protect against as both chassis become
active. This can obviously have adverse effects on network stability
because both chassis use the same IP addresses, SSH keys, and STP bridge ID.
If a client still wishes to go ahead without the additional link, then I
raise it as a risk which the client accepts before proceeding with the
implementation. The only times this has been raised is when the chassis
are some distance apart and the link has to be leased. At all other
times the link should be implemented as standard if both chassis are
within the same data-center.

regards Andy

KRATTIGER Lukas wrote:
> Hi Andy
> Your so called sync-link is not needed, this will run on the 10G VSL links.
> There is no requirement to have an additional 1G link between the chassis.
> A 1g link for dual-active detection would be helpfull but not required.
> Cheers
> -Lukas
>
> ________________________________
>
> Von: Andy Reid [mailto:ccie_at_reid.it]
> Gesendet: Di 04.08.2009 17:20
> An: KRATTIGER Lukas
> Cc: Ram Shummoogum; ccielab_at_groupstudy.com
> Betreff: Re: AW: AW: VSS and PFC3A
>
>
>
> Hi Ram,
>
> Remember if you have 10GE cards installed it is not possible to remove
> their DFC's as they come installed as standard, which leaves the upgrade
> supervisor option. Note that you cannot have two supervisors in the same
> chassis when switching to VSS mode (at least not at the current SXI
> release). Only one supervisor in each chassis is supported, and each
> must be a VS-S720-10GE-3C or VS-S720-10GE-3CXL. It is not possible to
> use an older supervisor in each chassis and use 10GE cards (such as the
> 4, 8 or 16 port versions).
> Don't forget that you also need a synchronization link between the two
> chassis once cut-over - this is usually a 1GE copper link if they are
> the same room - it does not carry client traffic but information such as
> keep-alives and state information.
>
> regards Andy
>
> KRATTIGER Lukas wrote:
>
>> Hi Ram
>>
>>
>>
>> You are correct. The DFC, CFC are on the linecards. There are also
>> limitations according to the daughter cards.
>>
>> The only VSS compatible Supervisor is the VS-S720-10GE-3C/XL. It's a
>> Sup720 with 2x 10G and PFC3c on it. All other Sups are not able to do
>> VSS.
>>
>>
>>
>> I hope this helps.
>>
>>
>>
>> Cheers
>>
>> -Lukas
>>
>>
>>
>> Von: Ram Shummoogum [mailto:rshummoo_at_ca.ibm.com]
>> Gesendet: Dienstag, 4. August 2009 16:44
>> An: KRATTIGER Lukas
>> Cc: ccielab_at_groupstudy.com
>> Betreff: Re: AW: VSS and PFC3A
>>
>>
>>
>>
>>
>> Thanks for getting back so fast.
>>
>> When you say remove the PFC3A and replace with CFC or DFC3c/DFC3cXL: Are
>> you referring to the SUP720. I thought CFC and DFC are only for
>> linecards.
>>
>> For the line cards I am good as they are new and are DFC3C.
>>
>> Thanks
>>
>>
>>
>>
>>
>>
>> "KRATTIGER Lukas" <Lukas.KRATTIGER_at_nextiraone.ch>
>>
>> 08/04/2009 10:38 AM
>>
>> To
>>
>> Ram Shummoogum/Quebec/IBM_at_IBMCA, <ccielab_at_groupstudy.com>
>>
>> cc
>>
>>
>> Subject
>>
>> AW: VSS and PFC3A
>>
>>
>>
>>
>>
>>
>>
>>
>> Hi Ram
>>
>> Just remove your PFC3A and replace it with a CFC or buy a DFC3c/DFC3cXL.
>> These are your two options.
>> A VSS will never work with distributed forwarding below 3c.
>> Just as a side note: The linecards for your VSLs need to have a
>> DFC3c/DFC3cXL on it.
>>
>> Cheers
>> -Lukas
>>
>>
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Received on Wed Aug 05 2009 - 00:32:33 ART