IE4010 MRP Ring - network storm after restart

[pserralheiro]

Hi all,

I am involved in a project where it will be necessary to expand the profinet network. During the testing of the new IOS releases, I noticed that whenever I have a MRP ring closed and I restart the MRM (Cisco IE4010), I get a network storm.

However after it open the ring and close the ring again, the network stabilizes as it should.

After I have tried several IOS releases, I found out the problem arose after 15.2(7)E3.

I also identify that on any IOS release tested,15.2(7)E2, 15.2(7)E3, 15.2(7)E4, 15.2(7)E5, 15.2(8)E and 15.2(8)E1, after restarting the MRM (Cisco IE4010) with the MRP ring closed, the led lights of blocked MRM port and forwarding MRP port are flashing continuously when the blocked MRM port should be fixed on. The led lights returns to normal behavior after open and close the MRP ring.

Test scenario:

1x IE-4010-16S12P (MRM/MRA) + 3x IE-2000-8TC-B (MRC)

MRM Config:

profinet
no profinet mrp
profinet vlan 1110
profinet id teste1

!

mrp ring 1
mode auto-manager
domain-id 550e8400-e29b-41d4-1110-52462003a001
domain-name PROFINET_RENCB_MRP1
vlan-id 1110

!

interface GigabitEthernet1/13
description === Profinet - MRP Ring 1 ===
switchport trunk allowed vlan 1100,1110
switchport trunk native vlan 1110
switchport mode trunk
mrp ring 1
alarm profile RingPort
!
interface GigabitEthernet1/14
description === Profinet - MRP Ring 1 ===
switchport trunk allowed vlan 1100,1110
switchport trunk native vlan 1110
switchport mode trunk
mrp ring 1
alarm profile RingPort

MRC Config:

profinet
no profinet mrp
profinet vlan 1110
profinet id teste2

!

mrp ring 1
mode client
domain-id 550e8400-e29b-41d4-1110-52462003a001
domain-name PROFINET_RENCB_MRP1
vlan-id 1110

!

interface FastEthernet1/9
description === Profinet - MRP Ring 1 ===
switchport trunk allowed vlan 1100,1110
switchport trunk native vlan 1110
switchport mode trunk
mrp ring 1
alarm profile RingPort
!
interface FastEthernet1/10
description === Profinet - MRP Ring 1 ===
switchport trunk allowed vlan 1100,1110
switchport trunk native vlan 1110
switchport mode trunk
mrp ring 1
alarm profile RingPort

Has anyone experienced similar problems?

These industrial switches from Cisco are a brave trap...

Thanks,

Paulo Serralheiro

[Albert Mitchell]

Hello,

how many other MRP Managers are enabled in the MRP ring?

I ask because what you are experiencing is expected.

the MRP manager is auto-manager.  implying there's a negotiation going on with other potential MRP managers.  when the MRP manager reloads and comes up, it has to forward on all interfaces to receive MRP protocol msgs.   once the MRP manager determines there are no other managers on the ring, it becomes the manager, and closes one port.

if reloading the MRP manager node is a frequent occurrence, you should consider adding a redundant MRP manager to take over MRP manager role and keep one port closed.

[pserralheiro]

Hello Albert

As I wrote above my test scenario was:

1x IE-4010-16S12P (MRM/MRA) + 3x IE-2000-8TC-B (MRC)

I just have an switch in MRP manager mode (MRM) and three switchs in MRP client mode (MRC).
In case of switch in MRP manager mode (MRM), the lastest IOS releases only allow me to configure it in MRP auto-manager mode (MRA)

I understand your statement, but I only have an switch in MRP manager (MRM), actually in MRP auto-manager (MRA), so the election of the MRP manager should not be a problem and the network can never get a network storm indefinitely after reload, as it is the case. 

Before IOS release 15.2(7)E3, including this one, this was not a issue.

Regards

Paulo Serralheiro

[Albert Mitchell]

Hello,

the MRP auto manager feature was added in 15.2.5E3 release

https://www.cisco.com/c/en/us/td/docs/switches/connectedgrid/cg-switch-sw-master/software/release/notes/rn-15-2-5e2.html#pgfId-112534

the behavior change should be observeable from this release onwards.