NSX T Native Load Balancer: LbVIP is DOWN.
Article ID: 419855
Updated On:
Products
Issue/Introduction
Virtual Server is reported 'Down' in the NSX manager UI and on clicking on the errors tab there is no information indicating why the VIP is down. The VIP is inaccessible, however the pool members are up and accessible
Environment
VMware NSX
Cause
Misconfiguration in the LB rules that was causing the issue. The access logs have the following entries
Operation.Category: 'LbAccessLog', Operation.Type: 'Http', Lb.UUID: '1dd397ff-####-####-80cb-###########', Lb.Name: 'Aria Suite-LB', Vs.UUID: 'aa106d72-####-47ee-####-baa42a00e364', Vs.Name: 'vidmvirtualserver', Vs.Ip: '172.##.15.##', Vs.Port: '443', Pool.UUID: '326386db-####-49a7-####-############', Pool.Name: 'vidmserverpool', PoolMember.Ip: '172.##.15.##', PoolMember.Port: '443', Client.Ip: '172.##.15.##', Client.Port: '33690', Snat.Ip: '172.##.15.##', Snat.Port: '4872', HttpRequest.Method: 'POST', HttpRequest.UserAgent: 'ReactorNetty/1.1.19', HttpRequest.X-Fwd-For: '-', HttpRequest.Uri: '/SAAS/API/1.0/oauth2/token?grant_type=client_credentials', HttpRequest.Host: 'bobdcvidm.bankofbaroda.co.in', HttpResponse.Status: '400', HttpResponse.StatusCategory: '4xx', HttpResponse.Size: '435', HttpResponse.ServerTime: '0.004', HttpResponse.TotalTime: '0.004', Error.Reason: 'Pool member returned 400'
Entries in the sylogs of the Edge have the following entries
2025-11-06T09:37:40.990Z VCFE######.##########.co.in NSX 754297 LOAD-BALANCER [nsx@6876 comp="nsx-edge" subcomp="lb" s2comp="access" level="INFO"] [1dd397ff-####-####-80cb-###########][aa106d72-####-47ee-####-baa42a00e364] Operation.Category: 'LbAccessLog', Operation.Type: 'Http', Lb.UUID: '1dd397ff-####-####-80cb-###########', Lb.Name: 'Aria Suite-LB', Vs.UUID: 'aa106d72-####-47ee-####-baa42a00e364', Vs.Name: 'vidmvirtualserver', Vs.Ip: '172.##.15.##', Vs.Port: '443', Pool.UUID: '326386db-####-49a7-####-############', Pool.Name: 'vidmserverpool', PoolMember.Ip: '172.##.15.##', PoolMember.Port: '443', Client.Ip: '172.##.15.##', Client.Port: '1251', Snat.Ip: '172.##.15.##', Snat.Port: '4880', HttpRequest.Method: 'POST', HttpRequest.UserAgent: 'ReactorNetty/1.1.19', HttpRequest.X-Fwd-For: '-', HttpRequest.Uri: '/SAAS/API/1.0/oauth2/token?grant_type=client_credentials', HttpRequest.Host: 'bobdcvidm.bankofbaroda.co.in', HttpResponse.Status: '400', HttpResponse.StatusCategory: '4xx', HttpResponse.Size: '435', HttpResponse.ServerTime: '0.006', HttpResponse.TotalTime: '0.006', Error.Reason: 'Pool member returned 400'
The above log entries indicate that the issue is because the pool member is replying with an error code of 400.
An HTTP 400 error indicates that the server could not understand a client's request because of a client-side issue, such as a malformed request, invalid syntax, or corrupted browser data.
Common causes include incorrect characters in a URL, problems with cookies or cache, and improperly formatted request headers or payloads
Checked the LB rules and the configuration was as follows
Resolution
Reconfigured the LB by changing the LB rules from "Action: HTTP Request URI Rewrite" to "Action: HTTP Request Header Rewrite" fixed the issue
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