BGP Route Lookup & Propagation Checker
Check how your network is advertised across the internet. Look up BGP routes, AS paths, communities, and verify global route propagation from multiple route servers worldwide.
Our free BGP route lookup tool allows you to check how IP prefixes and networks are advertised across the global internet. Query multiple route servers worldwide to see AS paths, BGP communities, origin ASNs, and route propagation. Perfect for network engineers, ISPs, and anyone managing internet routing. Get instant visibility into your network's BGP announcements and troubleshoot routing issues.
About BGP Route Lookup
BGP (Border Gateway Protocol) is the routing protocol that makes the Internet work. This tool shows how your network routes are propagated across different global locations.
- AS Path: The sequence of autonomous systems a route passes through
- Communities: BGP attributes used for route filtering and policy
- Origin AS: The autonomous system that originally advertised the prefix
- Route Servers: Global locations where we check BGP routing information
What is BGP Route Lookup?
BGP (Border Gateway Protocol) is the routing protocol that powers the entire Internet. A BGP route lookup tool allows you to see how IP prefixes (network blocks) are advertised and propagated across different parts of the internet through various Autonomous Systems (AS).
This tool queries multiple route servers (also called Looking Glass servers) located around the world to show you:
- AS Path: The sequence of autonomous systems that a route passes through from its origin to various destinations
- Origin AS: The autonomous system number (ASN) that originally announced the IP prefix to the internet
- BGP Communities: Special tags attached to routes that control how they are propagated and filtered across networks
- Route Propagation: How consistently your routes are advertised across different geographic locations
- Path Length: The number of AS hops a route takes, which can affect routing decisions and latency
How to Use the BGP Lookup Tool
- Enter IP or Prefix: Type an IP address (e.g., 8.8.8.8), CIDR prefix (e.g., 8.8.8.0/24), or ASN (e.g., AS15169) in the search field.
- Click Lookup: The tool will query multiple route servers across different continents to gather BGP routing information.
- View Results: See detailed BGP route information including AS paths, communities, and propagation consistency across locations.
- Analyze Propagation: Check if your routes are consistently advertised across all locations and review the AS path lengths.
- Export Data: Copy or share the results for documentation or troubleshooting purposes.
Key Features
Global Route Servers
Query route servers in 8+ locations including USA, Europe, Asia, South America, and Australia for comprehensive coverage.
AS Path Analysis
See the complete path your routes take through the internet, helping identify potential routing loops or inefficiencies.
BGP Communities
View BGP community attributes to understand route policies and filtering applied by different networks.
Propagation Check
Verify that your routes are properly propagated globally and identify any regional routing issues.
Understanding Your BGP Results
AS Path Interpretation
The AS path shows the route from the querying location back to the origin. Reading left to right, each AS number represents a network the route passes through:
- Shorter paths (2-4 hops): Generally better, with lower latency and fewer points of failure
- Medium paths (5-8 hops): Normal for global routing between different regions
- Longer paths (9+ hops): May indicate suboptimal routing or multiple transit providers
Route Consistency
Route consistency indicates how uniformly your prefix is advertised across different locations:
- 100% Consistent: Same origin AS from all locations - ideal situation
- 80-99% Consistent: Minor variations, usually acceptable
- <80% Consistent: May indicate route leaks, hijacks, or misconfiguration
BGP Communities
BGP communities are tags in the format AS:VALUE that control routing policies:
- Regional tags: Control which regions receive the route
- LOCAL_PREF modifiers: Affect route preference within a network
- NO_EXPORT: Prevents route from being advertised to eBGP peers
- NO_ADVERTISE: Prevents route from being advertised to any BGP peer
Common Use Cases for BGP Lookup
Network Troubleshooting
- Verify that new route announcements are propagating globally
- Identify routing loops or suboptimal AS paths
- Check if routes are being filtered unexpectedly
- Diagnose connectivity issues related to BGP routing
Security Monitoring
- Detect BGP hijacking attempts on your IP space
- Monitor for unauthorized route announcements
- Verify RPKI (Resource Public Key Infrastructure) validation
- Track changes in BGP routing for security incidents
Peering Analysis
- Evaluate potential peering partners and their AS paths
- Analyze traffic engineering opportunities
- Compare routes before and after peering arrangements
- Optimize multi-homed BGP configurations
Capacity Planning
- Understand current routing patterns for your networks
- Plan for geographic expansion of services
- Evaluate transit provider diversity and redundancy
- Assess impact of route policy changes
BGP Best Practices
- Monitor Regularly: Check your BGP routes periodically to catch issues early before they impact service.
- Use Prefix Filtering: Implement strict prefix filters to prevent accidental route leaks or malicious hijacking.
- Implement RPKI: Deploy Resource Public Key Infrastructure to validate route origins and prevent prefix hijacking.
- AS Path Prepending: Use AS path prepending carefully to influence inbound traffic patterns without over-engineering.
- Document Communities: Maintain clear documentation of your BGP community usage for traffic engineering and filtering.
- Multi-homing: Consider multiple upstream providers for redundancy and improved routing diversity.
- Route Aggregation: Announce appropriate CIDR blocks to reduce global routing table size and improve convergence.
BGP Troubleshooting Guide
Route Not Visible Globally
If your routes aren't showing up in all locations:
- Check that your upstream provider is properly accepting and propagating your routes
- Verify that prefix filters aren't blocking your announcements
- Ensure your prefix is the correct size (most networks accept /24 or larger for IPv4)
- Confirm BGP sessions with upstream providers are established
Inconsistent AS Paths
If you see different origin ASNs from different locations:
- May indicate a BGP hijacking attempt - investigate immediately
- Could be a misconfigured route announcement from a peer
- Check for route leaks from downstream customers
- Verify that AS path prepending isn't being stripped by a provider
Suboptimal Routing
If routes are taking longer paths than expected:
- Review your BGP communities and LOCAL_PREF settings
- Check if cold-potato routing is preferred over hot-potato
- Evaluate peering relationships and direct connections
- Consider adjusting MED (Multi-Exit Discriminator) values
Frequently Asked Questions
What is BGP and why is it important?
BGP (Border Gateway Protocol) is the protocol that routes traffic across the entire Internet. It's how different networks (autonomous systems) communicate routing information to each other. Without BGP, the Internet as we know it wouldn't exist. Understanding BGP is crucial for anyone managing network infrastructure or troubleshooting internet connectivity issues.
How often should I check my BGP routes?
For production networks, it's recommended to monitor BGP routes continuously using automated tools. Manual checks with a BGP lookup tool should be performed: whenever you make routing changes, at least weekly for important prefixes, immediately if you suspect routing issues, and after changing upstream providers or peering arrangements.
What is an AS (Autonomous System)?
An Autonomous System (AS) is a collection of IP networks and routers under the control of a single organization that presents a common routing policy to the Internet. Each AS is identified by an AS Number (ASN), like AS15169 for Google. Organizations get ASNs from regional internet registries (RIRs) like ARIN, RIPE, APNIC, etc.
What are BGP communities used for?
BGP communities are tags (in the format ASN:VALUE) attached to routes that control how they're handled by different networks. They're used for traffic engineering, route filtering, marking routes with special attributes, controlling route propagation across regions, and implementing complex routing policies. Many ISPs publish their community values for customer use.
How do I get my own ASN?
To get an ASN, you need to: 1) Be a member of your regional internet registry (RIR), 2) Demonstrate a unique routing policy or multi-homing requirement, 3) Submit an ASN request to your RIR with justification, 4) Pay applicable fees (typically a few hundred dollars annually). Once approved, you can use the ASN to announce your IP space via BGP.
What is BGP hijacking?
BGP hijacking occurs when a malicious actor announces IP prefixes they don't own, causing traffic intended for those IPs to be routed to them instead. This can be accidental (misconfiguration) or intentional (attack). RPKI and route monitoring help detect and prevent hijacking. Always monitor your prefixes and implement proper filtering.
Why do I see different AS paths from different locations?
Different AS paths from different locations are normal because BGP routing is path-vector based and each network makes independent routing decisions. Factors include: local peering relationships, geographical proximity, business relationships between ASNs, traffic engineering policies, and local routing preferences. Major variations might indicate issues.
What is the difference between iBGP and eBGP?
iBGP (internal BGP) is used within a single AS to distribute external routing information between routers. eBGP (external BGP) is used between different autonomous systems to exchange routing information. eBGP modifies the AS path by adding ASNs, while iBGP doesn't modify the AS path. Different rules apply for each regarding route selection and propagation.
How long does BGP route propagation take?
BGP route propagation typically takes 1-5 minutes to reach most of the Internet, though full global propagation can take up to 15-30 minutes. Factors affecting speed include: BGP update intervals (usually 30-60 seconds), number of AS hops to traverse, route processing time at each AS, and network congestion. Route withdrawals propagate faster than new announcements.
Can I use this tool for IPv6?
Yes, BGP lookup tools work for both IPv4 and IPv6 prefixes. Simply enter an IPv6 address or prefix (e.g., 2001:4860::/32) in the same way you would an IPv4 address. IPv6 BGP operates similarly to IPv4 BGP but uses separate routing tables and may have different AS paths due to varying IPv6 deployment across networks.