# iBGP Local-AS Next Hop Requirements

DevFeed: [iBGP Local-AS Next Hop Requirements](<https://devfeed.tech/articles/ibgp-local-as-next-hop-requirements-11168.md>)

Original publisher: [Read original article](<https://blog.ipspace.net/2025/04/ibgp-local-as-details/>)

Published: 2025-04-08T06:08:00Z

Content type: article

Language: en

Sources: [ipSpace.net blog](<https://devfeed.tech/sources/ipspace-net-blog.md>)

Topics: [BGP](<https://devfeed.tech/topics/bgp.md>), [Network](<https://devfeed.tech/topics/network.md>), [Protocol (disambiguation)](<https://devfeed.tech/topics/protocol.md>)

Tags: [bgp](<https://devfeed.tech/tags/bgp.md>), [configuration](<https://devfeed.tech/tags/configuration.md>), [network](<https://devfeed.tech/tags/network.md>), [operating-systems](<https://devfeed.tech/tags/operating-systems.md>), [route](<https://devfeed.tech/tags/route.md>), [router](<https://devfeed.tech/tags/router.md>), [test](<https://devfeed.tech/tags/test.md>)

## AI overview

This article examines the requirements and caveats of using BGP local-as to simulate an iBGP session between different autonomous systems. Integration testing across multiple platforms found that neighbor next-hop-self is required because the next hop is not changed on an iBGP session and may otherwise be unreachable without an underlying IGP.

## Source excerpt

Did you know you could use the neighbor local-as BGP functionality to fake an iBGP session between different autonomous systems? I knew Cisco IOS supported that monstrosity for ages (supposedly "to merge two ISPs that have different AS numbers") and added the appropriate tweaks1 into netlab when I added the BGP local-as support in release 1.3.1. Someone couldn't resist pushing us down that slippery slope, and we ended with IBGP local-as implemented on 18 platforms (almost a dozen network operating systems). I even wrote a related integration test, and all our implementations passed it until I asked myself a simple question: "But does it work?" and the number of correct implementations that passed the test without warnings dropped to zero. Read more ...