Redistribution loop issue

[ElshanMammadli5597]

We faced with routing loop issue.  Brief desciription is below.

We have two network . one network are  consist of cisco devices (NCS5500 ) and  second network are consist of huawei devices, 

Between cisco devices runs ISIS as IGP protocol and bet huawei devices runs ospf in same role. to provide end to end services we have to connect this two network and redistribute isis to ospf and vice verse. we already did it with one connnection  and all are working. we applied route-policy to isis for filter redistrubed pefixes and distribute-list ospf for filtered prefixes. but we have to connect second connection in other routers and have to do redistribution process again. when we connect  second connection , appears rooting loop. we applied route-policy and distribute-list but result is same .how  we prevent this issue or which solution we may use.

Simple network topology attached

 

[guruvignesh]

Hello Elshan,

To prevent a routing loop issue between two networks consisting of Cisco (NCS5500) and Huawei devices using different IGP protocols (ISIS and OSPF), a careful redistribution strategy is essential. Initially, redistribution of ISIS to OSPF and vice versa was successful for one connection. However, upon adding a second connection, a routing loop emerged.

To resolve this, you should review the redistribution process and policies. Ensure that the route policies for both ISIS and OSPF are correctly configured to filter and control the prefixes being redistributed. Pay close attention to any filtering mechanisms, such as route-maps or distribute-lists, to prevent unwanted prefixes from entering the other network.

Additionally, validate that the redistribution setup for the second connection mirrors the successful setup for the first connection. Consistency in configuration is key to avoid discrepancies that could lead to routing loops.

Lastly, carefully analyze the network topology and routing tables to identify any irregularities or unexpected routes. Addressing these inconsistencies and fine-tuning redistribution policies should help resolve the routing loop issue and establish stable connectivity between the two networks.

[ElshanMammadli5597]

we use same routing policy and distribution-list. We accept same routes from ospf side and redistribute same isis routes to ospf. The issue appears when second ospf neighbourship establishes which We dont apply redistribution route-policy to isis yet

[MHM Cisco World]

Make AD of OSPF E1/E2 higher 

[ElshanMammadli5597]

Can you share any documentation about this process 

[MHM Cisco World]

https://www.ccexpert.us/routing-switching-2/mutual-redistribution-at-multiple-routers.html