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BGP

BGP Next-Hop-Self: When and Why You Need It

One of the most common iBGP problems is routes that show up in the BGP table but never hit the routing table because the next-hop is unreachable. Here is when next-hop-self is the fix, and when it actually makes things worse.

J

Mar 28, 2026 5 min read

BGP

How to Configure iBGP Neighbors and Full Mesh

iBGP has rules eBGP does not: split-horizon, full-mesh, and next-hop preservation. Ignore any of them and routes vanish silently from your network. A practical guide to configuring iBGP neighbors and full mesh.

J

Mar 28, 2026 5 min read

BGP

How to Configure eBGP Neighbors on Cisco IOS XE

A single mismatch in neighbor IP, AS number, or filtering keeps a BGP session down without a helpful error. A practical Cisco IOS XE eBGP configuration walkthrough including dual-homed peering and source/TTL considerations.

J

Mar 28, 2026 6 min read

BGP

How BGP Advertises Routes: NLRI, Withdrawn Routes, and the Adj-RIB

BGP does not auto-advertise connected interfaces like OSPF. Routes must be injected via network, redistribution, or aggregation. Understand NLRI, withdrawn routes, and the Adj-RIB pipeline to control what you advertise.

J

Mar 28, 2026 4 min read

BGP

BGP Best Path Selection Algorithm — All 13 Steps

Cisco BGP picks the best path with a 13-step algorithm. Most real decisions resolve in steps 1 to 5, but troubleshooting unexpected path selection means knowing every step. A complete walkthrough with examples.

J

Mar 28, 2026 5 min read

BGP

BGP Session Authentication: MD5 and TCP-AO

An unauthenticated BGP session is vulnerable to TCP-based attacks and spoofed RSTs. MD5 has been the standard for decades; TCP-AO is the modern replacement. A practical guide to BGP session authentication.

J

Mar 28, 2026 4 min read