Solved: 3750 Stackwise LAN Core Suitability?

leon_taylor · ‎03-22-2005

We are thinking of using 2 x EMI 3750s and 4 x SMI 3750s in a stack for a new LAN installation for a medium sized office. Each EMI will connect to a different WAN provider for resilience. The question I have is the suitability of such a design as I am concerned about the election process. If for instance, there is a power issue onsite and the 2 x EMIs come up later than the SMI, the SMI will remain master and will potentially over-write the routing configuration.

Is this a valid concern or is there configuration that can be made to resolve this (I have found that preempt is not available so far..?).

Any help appreciated.

Thanks

LT

alagrawa · ‎03-22-2005

Hi Leon,

Thanks for writing in. You're correct. If both the EMI switches rebooted and a SMI switch became master, there is no way to make the EMI switch the master, unless you reload the current SMI master. There is no workaround for this currently.

I believe the logic is that there is less chance of both EMI switches going down at the same time. If both EMI switches do go down at the same time, I'm guessing whatever caused the two EMI switches to go down will probably cause the rest of the SMI switches to go down too.

Hence it is recommended to have 2 EMI switches in the stack, so that if one EMI switch goes down, the 2nd EMI switch will become master and the stack will not lose its layer 3 functionality.

Havent really added any new informatio here. But can confirm that there is no other workaround for this scenario at the moment.

regards

-Alok

View solution in original post

rloser · ‎03-22-2005

Hi Leon,

i think you should configure the EMI-Switch to the Master.

Switch(Conf)#

Switch prio (example) 15,

These should lose your problem

Best regards

Rainer

Dimension Data

leon_taylor · ‎03-22-2005

The plan is to configure EMI primary as 15 and the secondary EMI as 10. The remaining SMIs can stay as the default 1 priority.

My issue is that if for example, the 2 x EMIs rebooted (or came up much later than the SMIs for whatever reason) one of the SMI's would become the Master by default. When the 2 x EMI's come back online from what I understand no re-election/preemption occurs. Therefore, the SMI stays as master and L2 is only available on the LAN.

Any ideas...?

Thanks

alagrawa · ‎03-22-2005

Hi Leon,

Thanks for writing in. You're correct. If both the EMI switches rebooted and a SMI switch became master, there is no way to make the EMI switch the master, unless you reload the current SMI master. There is no workaround for this currently.

I believe the logic is that there is less chance of both EMI switches going down at the same time. If both EMI switches do go down at the same time, I'm guessing whatever caused the two EMI switches to go down will probably cause the rest of the SMI switches to go down too.

Hence it is recommended to have 2 EMI switches in the stack, so that if one EMI switch goes down, the 2nd EMI switch will become master and the stack will not lose its layer 3 functionality.

Havent really added any new informatio here. But can confirm that there is no other workaround for this scenario at the moment.

regards

-Alok