experiences with VSS 1440

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Jan 16th, 2008
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Hi experts,

The VSS 1440 seems to be the ideal solution for lots of situations. However, I am a bit worried about the stability of this new product.

Is there anyone who deployed or tested the VSS1440 and wants to share experiences?

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mogli Wed, 01/16/2008 - 13:17
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today we've started testing VSS using the whitepaper from cco. unfortunatly we think that we found some inconsistency between the document and real configuration.

the "preempt" command can't be configured with the time parameter as documented in the whitepaper. this option is just not possible to enter (it would be interesting which image the use to build the whitepaper ;-)

additionally when configuring the preempt function, the VSL Link never comes up again when doing a reboot. first switch1 was rebooted, when up again the 2nd switch reboots 'cause he noticed that switch1 with preempt configured is back again. when then switch2 comes up again, VSL doesn't see's it's neighbor and hence Switch2 is also active - dual active

can anyone confirm or disprove our experience? we did it twice (starting every time from factory default) and both time it leads to the same "unexpected" result...

mogli Thu, 01/17/2008 - 09:42
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new day, new experience ;-) we began again from factory default again and noticed the following configuring step listed in the whitepaper is not available:


Step 4. Finalize the virtual switch configuration.

This final, critical step is applicable only for a first-time conversion. If the switch has been converted or partially converted already, you cannot use this command.

When the standby virtual switch is in SSO hot mode, you must execute the following command to automatically configure the standby virtual switch configuration on the active virtual switch:

VSS#switch accept mode virtual

This command will bring in all VSL configurations from the standby switch and populate it into the running configuration.

In addition the startup configurations will be updated with the new merged configurations.

Do you want proceed? [yes/no]: yes

Merging the standby VSL configuration. . .

Building configuration...


This command prompts you to accept all standby virtual switch VSL-related configurations and also updates the startup configuration with the new merged configurations. Note that only VSL-related configurations are merged with this step-all other configurations will be lost and require manual intervention.


this command doesn't exist in our ios version.

Cisco IOS Software, s72033_rp Software (s72033_rp-IPSERVICESK9_WAN-VM), Version 12.2(33)SXH, RELEASE SOFTWARE (fc5)

it seems that my yesterday's "VSL-Down" problems were releated with unavailable command....

anyone made similar experiences?

mogli Fri, 01/18/2008 - 00:58
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...as vss only runs on the 10G Sup - yes, we have them twice ;-)

when i understand you correctly, the "switch accept mode virtual" command is not available in the current (only) software for vss??

if that's true, it would be interesting which software cisco was using to create the whitepaper...


apart from that, this whitepaper is referencing several times to 12.2(33)SXH

is there another configuration guide for vss?

daniel.sandstro... Wed, 01/30/2008 - 02:03
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Command works in 12-33.SXH IPBASE software... missing in IPSERVICES... bug ?

Also as you mention the command "dual-active pair int xx int xx bfd" seems to be replaced with "dual-active pair int xx int xx direct" in the IPservices sofware - inconsistent !

Note : Whitepaper says :

Step 4. Finalize the virtual switch configuration.

This final, critical step is applicable only for a first-time conversion. If the switch has been

converted or partially converted already, you cannot use this command.

bilousand Wed, 01/30/2008 - 02:44
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The documentation refer to the 12.2(33)SXH as a whole train. To build VSS successfully you need at least 12.2(33)SXH1.

daniel.sandstro... Wed, 01/30/2008 - 02:48
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Not really, I just successfully built a system with the included software which is :


bilousand Wed, 01/30/2008 - 02:59
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Fun. Cisco insisted SXH1 is a minimum requirements. To bad I couldn't lay my hand on this hardware at the moment.

daniel.sandstro... Wed, 01/30/2008 - 03:31
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So it seems, well.. it might be so that VSS will run with SXH but with limitations... Probably SXH1 is the way to go then..

mogli Wed, 01/30/2008 - 03:09
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i just talk with our cisco representative about that topic and got the following information:

officially, vss is first supported with 12.2(33)SXH1. this matches with the release notes from the SXH Train (refer to http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/release/notes/ol_14271.html#wp3896239)

so in 12.2(33)SXH code it seems that VSS is not fully integrated (as i wrote, Step 4 is missing)

finally, we also successfully build a VSS system with 12.2(33)SXH, doing "Step 4" manually. after the reboot, when VSS was broken we again configed the VSL config from second switch (the port-channel), which was lost because the automatically merging of both configs did't work -> that's what Step 4 does ;-)

maybe the problem was that the white-paper doesn't say clearly that SXH1 release is needed to use VSS. they are only talking about 12.2(33)SXH , but it seems that they mean the whole software train and not the particular image....


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