Troubleshooting IX With a BGP Session Routing Issue
When a BGPBorder Gateway Protocol.
A standardized routing protocol designed to exchange route and reachability information among autonomous systems (AS) on the internet. session on Internet Exchange (IX) is experiencing a routing issue, step through these troubleshooting actions.
You can query the primary and redundant route servers for live BGP data here: MegaIX Looking Glass.
|Verify the BGP configuration||Check the ASN, BGP IP address, and subnet mask.|
|Verify access to TCP port 179||BGP neighbors establish a TCP session using TCP port 179.
|Check the BGP message type||BGP packets use these message types:
|Verify the MD5Message-digest algorithm.
A widely used cryptographic function producing a string of 32 hexadecimal digits. MD5 is used as a password or key between routers exchanging BGP information. authentication
|Run connectivity tests||
|Find error conditions in BGP logs||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 contacting support for assistance, collect the following information:
- All troubleshooting steps taken, in detail. For example, if you place loopbacks, note their location and direction.
- Note the date, time, and time zone in which the issue started.
- Is the BGP session down?
- Is the BGP session flapping? For example, does the peering establish, then drop, re-establish and then drop? Try to pinpoint where the problem might be in the network using ping.
- Is there a BGP routing issue?
When a field service technician is needed onsite at the data center, see Customer Field Services for details.
Collect essential troubleshooting data
BGP configuration information
- Interface settings, including VLANVirtual local area network.
A partitioned and isolated computer network at the data link layer (OSI Layer 2) on a single physical interface (for example, a Port) used to subdivide a network. number
- BGP IP address and subnet mask
- BGP ASN
- BGP network addresses to be advertised
- BGP neighbor IP address and subnet mask
- BGP neighbor ASN
- BGP neighbor network addresses to be received
- BGP authentication between BGP peers
- BGP route filtering and manipulation (if applicable)
BGP command output and packet capture information
- Examine the BGP neighbor table and BGP state using the show IP BGP summary command
- Examine the BGP neighbor details using the show IP BGP neighbors command
- Logs that show BGP-related messages (output from the show log %BGP-xxxxx command)
- BGP routing table entries that have BGP routing issues (output from the show IP BGP command)
- BGP advertised routes (output from the show IP BGP neighbors <neighbor-ip-address> advertised-routes command)
- BGP received routes (output from the show IP BGP neighbors <neighbor-ip-address> routes command)
- Routing table (output from the show IP route <ip-address> command) at both ends
- TracerouteA diagnostic tool that examines how data moves through the internet to determine if a destination is reachable. logs between source and destination host
- Packet capture logs, if possible (file size can be up to 10 M)
Last update: 2022-07-22