[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["難以理解","hardToUnderstand","thumb-down"],["資訊或程式碼範例有誤","incorrectInformationOrSampleCode","thumb-down"],["缺少我需要的資訊/範例","missingTheInformationSamplesINeed","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-09-05 (世界標準時間)。"],[],[],null,["# Troubleshoot BGP sessions\n=========================\n\nThis guide is for troubleshooting BGP sessions, such as BGP sessions that fail\nto establish and BGP resets.\n\nFor additional troubleshooting information, see the following:\n\n- [Troubleshoot BGP peering](/network-connectivity/docs/router/support/troubleshoot-bgp-peering)\n- [Troubleshoot BGP routes and route\n selection](/network-connectivity/docs/router/support/troubleshoot-bgp-routes)\n- [Troubleshoot Cloud Router log messages](/network-connectivity/docs/router/support/troubleshoot-log-messages)\n\nBGP session failed to establish\n-------------------------------\n\nCheck that the settings on your on-premises BGP router and the settings on\nyour Cloud Router are correct. For detailed information, view the\nCloud Router [logs](/network-connectivity/docs/router/how-to/viewing-logs-metrics).\n\nIf you're creating a Cloud VPN tunnel, check that the\n[status of the tunnel](/network-connectivity/docs/router/how-to/viewing-router-details) is\n`ESTABLISHED`. If it isn't, to troubleshoot the issue, see\n[Cloud VPN troubleshooting](/network-connectivity/docs/vpn/support/troubleshooting).\n\nIPv4 and IPv6 addresses for BGP sessions\n----------------------------------------\n\nSupport for IPv6 BGP sessions is in\n[Preview](/products#product-launch-stages).\n\nThe IPv4 and IPv6 addresses that you can use for a BGP session depend on the\nproduct you use. For complete details, see [BGP peering\naddresses](/network-connectivity/docs/router/how-to/configuring-bgp#bgp-peering-addresses).\n\nInvalid value for the field `resource.bgp.asn`\n----------------------------------------------\n\nYou may get the following error:\n\n*\"Invalid value for field `resource.bgp.asn`: `######`.\nLocal ASN conflicts with peer ASN specified by a router in the same region\nand network.\"*\n\nThe Cloud Router is attempting to establish a BGP session with an\non-premises device that has the same ASN as the Cloud Router. To resolve\nthis issue, change the ASN of your device or Cloud Router.\n\nIPv6 BGP session fails to establish\n-----------------------------------\n\nIf you are experiencing difficulty establishing a connection with your IPv6 BGP\npeer, do the following:\n\n1. Verify that the corresponding VLAN attachment or HA VPN\n tunnel is connected.\n\n2. Verify that the VLAN attachment or HA VPN gateway has the\n required stack type of `IPV4_IPV6`.\n\n If the stack type is incorrect for a VLAN attachment, modify\n the VLAN attachment. For a HA VPN gateway, recreate the\n HA VPN gateway and its tunnels.\n\n3. Ensure that the Cloud Router is configured correctly and that your\n on-premises router is configured with the matching IPv6 BGP addresses.\n\n Run the following command: \n\n gcloud compute routers describe ROUTER-NAME\n\n In the command output, check the following values:\n - `bgpPeers.peerIpAddress` is an IPv6 address assigned to the external\n interface on your on-premises router. This IPv6 address is used as the\n BGP peering address with Cloud Router for a\n HA VPN tunnel or a\n Dedicated Interconnect VLAN attachment.\n\n - `bgpPeers.ipAddress` is an IPv6 address assigned to the interface of the\n Cloud Router and matches the value configured as the peer BGP\n IP address on your on-premises router.\n\n - `bgpPeers.peerAsn` matches the ASN of your on-premises router.\n\n - `bgp.asn` matches the peer ASN configured on your on-premises router.\n\nBGP resets that originate from Google Cloud appear on your router\n-----------------------------------------------------------------\n\nCloud Router tasks are software processes in the Google Cloud\ncontrol plane that are normally migrated from machine to machine. During such\nmigrations, the Cloud Router might be down for periods of up to 60\nseconds. Normal migrations don't cause traffic to be dropped.\n\nThe Cloud Router is not located in the data path and is not acting as a\nLayer 3 switch, but as a manager for route programming. Routing is actually\nhandled by the VLAN attachment or the Cloud VPN tunnel.\n\nCloud Logging adds entries for the affected router when BGP resets occur. You\ncan find the events by searching the Logging logs for the routing\nID and using the key `textPayload=\"Router Event: Router task activated`.\n\nFor more information about viewing Logging logs, see [View logs\nand metrics](/network-connectivity/docs/router/how-to/viewing-logs-metrics).\n\nOn-premises router experiences BGP flap\n---------------------------------------\n\nBGP flaps can be caused by various issues, including Cloud Router\n[software maintenance](/network-connectivity/docs/router//concepts/how-cloud-router-works#maintenance).\n\nTo get details about completed maintenance events, see [Identifying router\nmaintenance events](/network-connectivity/docs/router/how-to/identifying-router-events). To get\ndetails about other Cloud Router events, see [Viewing\nCloud Router logs and\nmetrics](/network-connectivity/docs/router/how-to/viewing-logs-metrics).\n\nA Cloud Router maintenance event is not indicative of a problem if your\non-premises router is configured as follows:\n\n- The on-premises router can process graceful restart notifications.\n- The on-premises router's hold timer is set to at least 60 seconds.\n\nFor a comprehensive overview of timer settings, see [Managing BGP\ntimers](/network-connectivity/docs/router/how-to/managing-bgp-timers).\n\nFor help monitoring connectivity, see [Verify connectivity between the\non-premises router and the\nCloud Router](/network-connectivity/docs/router/how-to/identifying-router-events#verify-connectivity).\n\nWhat's next\n-----------\n\n- For more information about how to use Cloud Logging to monitor\n Cloud Router, see\n [View logs and metrics](/network-connectivity/docs/router/how-to/viewing-logs-metrics).\n\n- For additional support, see\n [Getting support](/network-connectivity/docs/router/support/getting-support).\n\n- For information about BGP session states, see\n [BGP session states](/network-connectivity/docs/router/concepts/bgp-states).\n\n- For information about diagnostic messages and session states related to\n Bidirectional Forwarding Detection (BFD), see\n [BFD diagnostic messages and session states](/network-connectivity/docs/router/concepts/bfd-states).\n\n- For issues related to using Cloud Router with Router appliance,\n see\n [Troubleshooting Router appliance](/network-connectivity/docs/network-connectivity-center/support/troubleshooting#troubleshooting-ra)\n in the Network Connectivity Center documentation."]]
