Hi Jessie,
You mention two very different types of replacement - MPU and LPU replacement. We need to review both cases separately, as the impact of each scenario is very different:
1. LPU replacement.
The simplest case. Let's imagine you have a 7500 chassis with one or two MPUs installed, a couple of LPUs, all is running well and suddenly one LPU goes bad.
a. You decide to replace the failed LPU with the new one, same model. Then just plug out the LPU (this change in most cases can be done as hot-swap), insert the new one. Master MPU detects the new LPU, pushes the current Comware image to that LPU, LPU starts, gets configuration (since it's the same model, all ports are identical, so existing config applies with no changes) and starts forwarding traffic.
b. You decide to make an upgrade and replace, for example 1G 48 port LPU with compatible 10G 16 port LPU. Same story, MPU detects the new LPU, pushes the Comware image, LPU boots, but this time we have empty configuration on the ports, because old Gig3/0/1 port is not the new Ten3/0/1 thus the configuration of the new port stays empty and your task is to re-configure all the ports on the new LPU and save the configuration
2. MPU replacement.
a. Your 7500 chassis has one single MPU. The worst scenario. If you plug out the MPU, all LPUs will lose the connectivity to the 'main brain', probably they will keep their ports up and even will continue to forward traffic according existing FIB information, but now new MACs or IP-MAC (ARP) records will be learned. When you insert the replacement MPU (it must already have Comware image installed on its flash: memory) MPU will detect LPUs and force their reboot. On the reboot LPUs will get Comware image from the MPU. But here the question about 'saved-configuration' arises - if there is no 'saved-configuration' file on the MPU, the chassis will boot with the default config. If there is a configuration file, then MPU will program LPUs and push the configuration to all LPUs according the config file.
b. Your 7500 has two MPUs, one (failed) has to be replaced. The MPU that remains operating (Active) will keep communication with LPUs. You plug out the failed MPU, plug in the new one. Here we have two possibilities:
1) New MPU has Comware version installed that is the same version as Active MPU. In this case new MPU boots up and becomes Standby.
2) New MPU has Comware version installed that is different from the version in Active MPU. Again here we have two options:
i) If 'version auto-update enable' and 'undo version check ignore' commands are in the configuration (by default these are enabled), Standby MPU loads Comware version from the Active MPU
ii) If 'undo version auto-update enable' is in the config, the new MPU won't load and won't join the system as Standby MPU. In this case you need to get to the new MPU over the Console port and load the software on the new MPU's flash: manually.
Hope this helps!
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Ivan Bondar
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Original Message:
Sent: May 31, 2022 04:52 AM
From: Obioma Okoroafor
Subject: HP 7500 card replacement.
Hello Everyone,
The replacement guide does not make mention of any effects arising from card or part replacement, and as such,
It is my understanding that with HP 7500 switches, replacing the MPUs or LPUs does not affect either the
Firmware or the configuration, and that the replacement module does not affect the operation of the switch
if the models are the same.
Is my understanding correct?
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[Jessie]
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