Routing & BGP
How traffic finds you, anycast, and route withdrawal as a failure mode.
2 to work through
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advanced
A global edge network announces the same IP addresses from hundreds of locations. How does traffic reach the right one, what happens when a location fails, and what does this make harder?
2 min answer -
advanced
An edge network announces one anycast prefix from 40 locations. At one of them, the upstream transit begins dropping 8% of packets. BGP sessions stay established, the location's local health endpoint returns 200, and CPU is normal. What do users mapped there experience, and what stops it?
2 min answer
5 terms in this topic
Anycast Routing
Announcing the same IP address from many locations so that network routing delivers each client to the topologically nearest one.
protocolBGP
The protocol by which autonomous systems advertise which address ranges they can reach, determining how traffic finds any destination on the internet.
case-studyMeta 2021: The Outage That Locked Out Its Own Engineers
A backbone configuration command withdrew Facebook's BGP routes globally, and the tools needed to fix it depended on the network that had just disappeared.
practiceRoute Origin Validation
Checking a BGP announcement's origin against a signed authorisation before accepting it, so a more specific prefix announced by the wrong network is …
conceptRoute Propagation
Automatically inserting routes learned from a VPN or dedicated connection into a route table, rather than maintaining them by hand.
Neighbouring topics
Networking
General material on the network path underneath an architecture.
TCP/IP
Handshakes, congestion control, head-of-line blocking and connection reuse.
HTTP/1.1, HTTP/2 & HTTP/3
Multiplexing, prioritisation and the transport each is built on.
DNS
Resolution, TTL behaviour, traffic steering and failover latency.
TLS & Certificates
Encryption, integrity, authentication, termination points and expiry.
Layer 4 vs Layer 7
Connection-level versus request-level balancing, and what each unlocks.
Reverse Proxies
One place for TLS, routing, caching, compression and rate limiting.
Content Delivery Networks
Edge caching, origin offload, spike absorption and dynamic content.
Firewalls & Security Groups
Default-deny, stateful rules, and restricting egress as well as ingress.
NAT & Egress
Outbound-only connectivity, its per-gigabyte cost and its zone binding.
VPC Design
Address planning, peering and the ranges you can never resize.
Subnetting
Tiering, zone binding, and sizing for an address-hungry platform.
Service Mesh Networking
Sidecar proxies supplying mTLS, retries and traffic policy.
WebSockets & Realtime
Persistent bidirectional connections and the capacity model they impose.
gRPC Transport
HTTP/2 multiplexing, binary encoding and streaming semantics.
API Gateways
The single entry point, and the business logic that must stay out of it.
Network Performance
Latency floors, bandwidth-delay product, and what no code change fixes.
Private Connectivity
Private endpoints, peering and dedicated links to managed services.
Network Troubleshooting
Flow logs, packet paths, and localising a problem to a hop.