Troubleshooting IX BGP Session Down
If your Internet Exchange (IX) is down, there is likely an issue with your Border Gateway Protocol (BGP) session. Step through these troubleshooting steps to confirm whether your BGP session is the root cause of the IX issues.
Megaport operates a public, web-accessible MegaIX Looking Glass for peers and network operators to investigate the current routing state. You can query both the primary and redundant route servers for live BGP data here: MegaIX Looking Glass.
|Check interface or CRC errors and packet drops on the device||Interface statistics and logs can help identify which end of the cross connect is causing the fault, and the potential solution. For example, an increasing number of incoming errors on a network interface generally rules out that specific SFP (small form factor pluggable) and indicates a potential issue with other components of the IX.
Important to note:
Interface type, SFP type and cable type
|Verify interface, SFP, cable and cabling are correct||
|Verify Layer 2 configurations||
|Verify Layer 3 configurations||
|Verify the optic power levels on the device||Optic light readings from the terminal help to understand whether the readings are within the threshold range. Check the device and port graphs for errors and view the Megaport optic graphs history. The graphs update every five minutes, so if flapping is rare, the graphs might not capture a drop in optical light. Ensure the optic reading is within specifications.|
|Perform a ping test to route servers within the IX network and/or bilateral peers||A ping test transmits data packets to a specific IP address and either confirms or denies there is connectivity between IP-networked devices. A confirmation includes the latency (the response time) of the connection.
|Verify Layer 2 connectivity (ARP) to route servers and/or bilateral peers||Layer 2 controls the flow of data between nodes on WAN or LAN segments, and is also responsible for detecting and possibly correcting Layer 1 errors. Layer 2 connectivity issues can affect the functionality of your VXCs, which connect to your MCR. When connecting to a Cloud Service Provider (CSP), ensure that the VLAN configuration details are correct. Use particular caution when connecting to Azure, as you will be using Q-in-Q.
Layer 2 connectivity issues can also impact your IX services. MAC addresses are used to authenticate your devices when using IX services with Megaport. Depending on your network design, if you are peering with Megaport or other organizations, ensure that you have specified the correct MAC address in the Megaport Portal.
|Verify the BGP configuration||
|Check for BGP error messages||The BGP protocol sends a notification message when it detects an error with the BGP session such as an expiring hold timer, a change to neighbor capabilities, or a request to reset a BGP session. When an error is detected, the BGP session is closed.
For example, enter show log %BGP-xxxxx.
For details, see Internet Exchange Overview.
If the troubleshooting actions do not resolve your issue, contact support. Before requesting assistance, collect the following information:
- Provide all the troubleshooting steps you have taken in detail. For example, if loops were placed, note their location and which direction they faced.
Excerpts of network device configurations
- Interface configurations
- Static routes and routing protocol configurations (EIGRP/OSPF/BGP)
- Firewall rules and ACL configurations for the data flow that has the issue
BGP command output and packet capture information
- Routing table (show IP route <ip-address>) at both ends.
- Routing protocol status and the tables at both ends, for example, the BGP neighbor table that shows BGP state (show ip bgp summary) and BGP neighbor details (show ip bgp neighbors <neighbor-ip-address>).
- BGP routing table entries that have BGP routing issues (output from the command show IP BGP).
- BGP advertised routes (show IP BGP neighbors <neighbor-ip-address> advertised-routes).
- BGP received routes (output from the show IP BGP neighbors <neighbor-ip-address> routes command- Routing table (show IP route <ip-address>).
- Traceroute logs between the source and destination host.
- Packet capture logs, if possible (file size can be up to 10 M).