single-slot-reload-enable

[datacloud]

I have Cisco 7513 with STM-1 ATM interface, when I change the MTU size of the interface the router reloads it self.

I install an image that support single line card reload and add the command

Service single-slot-reload-enable

But is dos not work.

Here is the image that ruining now (rsp-pv-mz.122-25.S.bin)

[thisisshanky]

Do not know if you are running into a bug. There are numberous bugs in this code for which the fix itself is to change MTU size. Try configuring different MTU sizes each time you configure it and see if that helps!

What does a show version look like > Best bet is to copy a sh tech-support and contact Cisco TAC.

[jasyoung]

Are you certain that it goes through a full reload of the entire router? For any MTU size change on any interface on the 7500 platform, you have to do at least a MEMD recarve and possibly a full cbus complex restart depending on configuration and the version of IOS you're running.

http://www.cisco.com/warp/public/63/cbus_complex.html

I think perhaps you have seen that already, since you have already found the 'service single-slot-reload-enable' command. Note that the SLCR feature does not avoid all interruption, it only reduces it somewhat. There is no way to avoid service interruption entirely when changing MTU on the 7500 platform.

[marikakis]

If your router is in a lab, perhaps you could try a lot of MTU size changes,

though it would be difficult to reach a solid conclusion this way.

If your router is in a production environment,

you probably cannot afford another unexpected reload.

The book "Inside Cisco IOS Software Architecture" explains the general

intricacies of MEMD recarves due to MTU size changes in 7500s

(better than most documents found on the web do).

Output from "show controller cbus" would help to explain why this is

happening in your particular situation.

I would guess you had (at least) 2 pools of MEMD buffers:

1) for 1500 mtu-sized interfaces

2) for 4470 mtu-sized interfaces

I guess 4470 was the initial MTU for your STM-1 ATM interface.

Did you try to change it to 1500 ?

You probably entered a situation in which both RSPs had to update their MEMD pools.

Anyway, there is a work-around that you might try.

Do not change the MTU on your ATM main interfaces.

Instead, create ATM subinterfaces and try to change the MTU of the subinterface.

Normally, changing the MTU size of the subinterface does not cause a MEMD recarve,

because MEMD is distributed based on the MTU of main interfaces.

I hope this helps,

M.