Glossary

Every abbreviation used in the lessons, expanded and explained.

802.1Q IEEE 802.1Q VLAN tagging

The standard 4-byte tag added to Ethernet frames on a trunk, carrying the VLAN number (1–4094) so several VLANs can share one link. Read more Learn it in: Switching basics: layer 2, VLANs and IP addressing

ABR Area Border Router

An OSPF router with interfaces in area 0 and at least one other area. It keeps one LSDB per area and advertises summaries (Type 3 LSAs) between them. Read more Learn it in: OSPF Fundamentals

ACL Access Control List

An ordered list of permit/deny rules that filters packets on an interface. A common cause of routing adjacencies that won't form. Read more

ARP Address Resolution Protocol

How an IPv4 host finds the MAC address for an IP address on its own LAN: it broadcasts "who has X?" and caches the answer in the neighbour table. Read more Learn it in: Linux Network Connectivity

AS Autonomous System

A network, or group of networks, under one administration with a single routing policy towards the outside world. Identified by an ASN. Read more Learn it in: BGP Fundamentals

AS-SET AS set (RPSL as-set object)

A named group of ASNs and other as-sets, usually describing a network's customer cone. Neighbours expand it recursively to build prefix filters. Read more Learn it in: IRR, RPSL and AS-SETs

AS_PATH Autonomous System Path

BGP path attribute listing the ASes a route has crossed, nearest first. Used for loop prevention (reject routes containing your own ASN) and as a path-length tie-breaker. Read more Learn it in: BGP Fundamentals

ASBR Autonomous System Boundary Router

An OSPF router that redistributes routes from outside OSPF (static, connected or another protocol such as BGP) into OSPF as Type 5 or Type 7 LSAs. Read more Learn it in: OSPF Fundamentals

ASN Autonomous System Number

The number that identifies an AS in BGP. Originally 16-bit, now 32-bit (RFC 6793). 64512–65534 and 4200000000–4294967294 are private; 64496–64511 are for documentation. Read more Learn it in: BGP Fundamentals

ASPA Autonomous System Provider Authorization

A proposed RPKI object in which an AS signs the list of its upstream providers, so routers can detect forged paths and many route leaks. Still being standardised. Read more Learn it in: RPKI and Route Origin Validation

aut-num Autonomous system object

The RPSL object describing an AS: name, contacts, maintainers and, optionally, routing policy (import/export) and set memberships (member-of). Read more Learn it in: IRR, RPSL and AS-SETs

BDR Backup Designated Router

On an OSPF broadcast segment, the router that takes over from the DR if it fails. It forms full adjacencies with every router but stays quiet while the DR is alive. Read more Learn it in: OSPF Fundamentals

BFD Bidirectional Forwarding Detection

A lightweight hello protocol between two routers that detects a failed path in milliseconds, then tells OSPF, BGP or static routes so they can reroute far faster than their own timers allow. Read more Learn it in: Edge and core: building out a VyOS network

BGP Border Gateway Protocol

The path-vector routing protocol that exchanges reachability between autonomous systems on the internet, and inside large networks. Version 4 is defined in RFC 4271. Read more Learn it in: BGP Fundamentals

bgpq4 BGP filter generator

Command-line tool that expands AS-SETs and route objects from the IRR and prints ready-to-use prefix-lists or as-path filters for many router platforms. Read more Learn it in: IRR, RPSL and AS-SETs

BGPsec BGP Path Security

RFC 8205: each AS cryptographically signs the AS_PATH as routes pass through it. Complete protection in theory, but it needs every AS on the path to participate and is barely deployed. Read more

binfmt_misc Linux miscellaneous binary formats

A Linux kernel feature that hands programs it can't run itself, such as x86 binaries on an ARM machine, to a registered interpreter like Rosetta or QEMU. Read more Learn it in: Building a network lab on an Apple Silicon Mac

BPF Berkeley Packet Filter

The in-kernel filter language tcpdump uses (e.g. "tcp port 80 and host 203.0.113.20"), so only matching packets are copied to user space. Read more Learn it in: Packets That Never Come Back

CGNAT Carrier-Grade NAT

NAT run by the ISP, so customers get an address from 100.64.0.0/10 instead of a public one. Inbound connections and port forwards from the internet can't reach them. Read more

CIDR Classless Inter-Domain Routing

Writing a network as an address plus prefix length, e.g. 192.0.2.0/24, instead of fixed classes. It made route aggregation possible. Read more

CLLI Common Language Location Identifier

An 8–11 character telecom building code (e.g. town + state + building number), used by some carriers in router names. Read more

conntrack Linux connection tracking

The kernel table of flows a router has seen. Stateful firewalls and NAT depend on it; a packet that matches no tracked connection (e.g. a reply on an asymmetric path) is "invalid". Read more Learn it in: Packets That Never Come Back

DBD Database Description packet

OSPF packet used during adjacency formation (ExStart/Exchange) to list the headers of every LSA a router holds, so each side can work out what it is missing. Read more Learn it in: OSPF Fundamentals

DDoS Distributed Denial of Service

An attack that floods a target from many sources at once, often big enough to fill the target's links. RTBH, scrubbing services and rate limits are the usual defences. Read more

DF Don't Fragment bit

An IPv4 header flag telling routers not to fragment the packet. If it doesn't fit the next link, the router drops it and should send ICMP "fragmentation needed". Read more

DHCP Dynamic Host Configuration Protocol

Hands out an address, prefix, default gateway and DNS servers automatically, so hosts don't need manual configuration. Read more

DHCPv6-PD DHCPv6 Prefix Delegation

A DHCPv6 extension that hands a whole prefix (often a /56 or /48) to a downstream router, which then numbers its own LANs from it. How ISPs give IPv6 prefixes to customer routers. Read more Learn it in: IPv6 on VyOS: setup and routing

DMZ Demilitarised zone

A network segment for servers reachable from outside, kept separate from internal networks by a router or firewall. Read more

DNAT Destination NAT

Rewriting the destination address and/or port of incoming packets. Port forwarding is DNAT: a port on the public address is mapped to a host inside. Read more Learn it in: Setting up VyOS with NAT

DNS Domain Name System

Translates names such as server.lab.example into addresses. On Linux, applications resolve through /etc/nsswitch.conf, /etc/hosts and the resolvers in /etc/resolv.conf. Read more Learn it in: Linux Network Connectivity

DNSSEC DNS Security Extensions

Signatures on DNS records so resolvers can verify answers came from the zone owner unchanged. A DS record in the parent zone links each zone into the chain of trust. Read more

DR Designated Router

Elected on an OSPF broadcast segment to reduce flooding. Other routers form full adjacencies only with the DR and BDR, and the DR originates the segment's Network LSA (Type 2). Read more Learn it in: OSPF Fundamentals

DROther Non-designated router

An OSPF router on a broadcast segment that is neither DR nor BDR. DROthers stay at 2-Way with each other — that is expected, not a fault. Read more Learn it in: OSPF Fundamentals

DUID DHCP Unique Identifier

The identifier a DHCPv6 client uses to identify itself (instead of a MAC address). Servers key leases and delegated prefixes on it, so a stable DUID means a stable prefix. Read more

eBGP External BGP

A BGP session between routers in different ASes. The sender prepends its ASN to the AS_PATH and normally sets itself as NEXT_HOP. Read more Learn it in: BGP Fundamentals

ECMP Equal-Cost Multi-Path

Installing several next hops for one destination when their paths have exactly the same cost. Traffic is hashed per flow across them. Read more Learn it in: OSPF Fundamentals

EGP Exterior Gateway Protocol

Any protocol that routes between autonomous systems — today, effectively always BGP. (Also the name of an obsolete 1980s protocol, which is why BGP has an ORIGIN code "e".) Read more

EUI-64 64-bit Extended Unique Identifier

A way to build a 64-bit IPv6 interface identifier from a 48-bit MAC address (insert ff:fe in the middle and flip one bit). Many hosts now prefer random identifiers for privacy. Read more

EVPN Ethernet VPN

A BGP address family (RFC 7432) that carries MAC and IP reachability, used to build layer-2 and layer-3 overlays, typically over VXLAN in data centres. Read more Learn it in: EVPN and VXLAN: layer 2 over a routed fabric

FCrDNS Forward-confirmed reverse DNS

A name from a PTR lookup is only trusted if looking that name up again returns the original address. Mail servers commonly require it. Read more Learn it in: Linux Network Connectivity

FDB Forwarding Database

A switch's MAC address table: which MAC address was last seen on which port (and VLAN). Built by watching source addresses; entries age out after a few minutes of silence. Read more Learn it in: Switching basics: layer 2, VLANs and IP addressing

FIB Forwarding Information Base

The table the forwarding hardware actually uses to switch packets, programmed from the best routes in the RIB. Read more

FRR FRRouting

Open-source routing suite for Linux (BGP, OSPF, IS-IS and more), used in SONiC, VyOS, Cumulus and many appliances. Its CLI (vtysh) is close to Cisco IOS. Read more

FSM Finite State Machine

A model with a fixed set of states and the events that move between them. BGP peers (Idle → Established) and OSPF neighbours (Down → Full) are both defined as FSMs. Read more

GTSM Generalized TTL Security Mechanism

RFC 5082. Peers send packets with TTL 255 and only accept TTL 255 (or 255 − hops), so spoofed packets from further away are dropped. Configured in FRR with ttl-security. Read more Learn it in: BGP Fundamentals

IANA Internet Assigned Numbers Authority

Coordinates the global pools of IP addresses and AS numbers (handed out via the RIRs), the DNS root zone and protocol parameters. Read more

IATA International Air Transport Association

Its three-letter airport codes (SYD, LAX, FRA) are widely used in router names to show where a device is. Read more

iBGP Internal BGP

A BGP session between routers in the same AS. AS_PATH and NEXT_HOP are left unchanged, and routes learnt from one iBGP peer are not passed to another (unless via a route reflector). Read more Learn it in: BGP Fundamentals

ICMP Internet Control Message Protocol

IP's error and diagnostic messages: echo request/reply (ping), time exceeded (traceroute), destination unreachable and "fragmentation needed". Read more Learn it in: Linux Network Connectivity

ICMPv6 Internet Control Message Protocol for IPv6

IPv6's control protocol: errors, ping, path MTU discovery, and all of Neighbor Discovery. Unlike IPv4, IPv6 doesn't work if it's blocked. Read more

IGP Interior Gateway Protocol

A routing protocol used inside one autonomous system to find the best path between its own routers, e.g. OSPF or IS-IS. Optimised for fast convergence, not policy. Read more Learn it in: OSPF Fundamentals

inetnum IPv4 address registration object

The RIR database object recording who holds an IPv4 range (inet6num for IPv6). Its maintainers decide who may create route objects inside it. Read more Learn it in: IRR, RPSL and AS-SETs

iproute2 Linux networking tools

The package providing ip, ss and tc: the modern replacement for the deprecated ifconfig, route, arp and netstat. Read more Learn it in: Linux Network Connectivity

IRR Internet Routing Registry

Public databases (RADb, RIPE, ARIN…) where networks publish which prefixes they originate and their routing policy. Used to build inbound prefix filters, e.g. with bgpq4. Read more Learn it in: IRR, RPSL and AS-SETs

IRRd Internet Routing Registry daemon

Open-source IRR server software used by RADb and many others. Besides whois it answers short "!" queries (e.g. !g, !i) that tools like bgpq4 use. Read more

IS-IS Intermediate System to Intermediate System

A link-state IGP like OSPF, common in large service-provider networks. It runs directly over layer 2 rather than IP. Read more

IX Internet Exchange (IXP, Internet Exchange Point)

A shared layer-2 network where many networks connect to exchange traffic directly (peering), avoiding paying a transit provider for it. Usually peered via the IX's route servers. Read more Learn it in: Setting up VyOS with basic BGP

L3VPN Layer 3 VPN

A service that carries customer IP routes across a provider network in separate VRFs, usually with MP-BGP and MPLS (RFC 4364). Read more

LAN Local Area Network

A network in a limited area such as a building or a single Ethernet segment. In OSPF terms, usually a broadcast network type. Read more

LOCAL_PREF Local Preference

BGP attribute shared only inside an AS (iBGP). Higher wins. It is the main tool for choosing which exit your traffic uses, and is compared early in best-path selection. Read more Learn it in: BGP Fundamentals

LSA Link State Advertisement

A unit of OSPF topology information, such as a router's links (Type 1) or a summary from an ABR (Type 3). LSAs are flooded and stored in the LSDB. Read more Learn it in: OSPF Fundamentals

LSAck Link State Acknowledgement

OSPF packet confirming receipt of LSAs, which makes flooding reliable without TCP. Read more Learn it in: OSPF Fundamentals

LSDB Link State Database

The collection of LSAs a router holds for an area. All routers in an area have an identical LSDB, and SPF runs over it. Read more Learn it in: OSPF Fundamentals

LSR Link State Request

OSPF packet asking a neighbour for specific LSAs that are missing or newer, sent in the Loading state. Read more Learn it in: OSPF Fundamentals

LSU Link State Update

OSPF packet that carries one or more full LSAs, used both to answer requests and to flood changes. Read more Learn it in: OSPF Fundamentals

MAC Media Access Control address

The 48-bit hardware address of a network interface (e.g. 1a:dc:74:6a:45:dc), used to deliver Ethernet frames within one LAN. Read more

MANRS Mutually Agreed Norms for Routing Security

An industry initiative defining baseline routing-security actions: filtering, anti-spoofing, coordination and global validation (IRR/RPKI). Read more

MED Multi-Exit Discriminator

Optional BGP attribute that suggests to a neighbouring AS which of your entry points to use. Lower wins. By default only compared between routes from the same neighbouring AS. Read more Learn it in: BGP Fundamentals

mntner Maintainer object

The RPSL object holding credentials. Objects list it in mnt-by, and only someone who can authenticate as that maintainer may change them. Read more Learn it in: IRR, RPSL and AS-SETs

MPLS Multiprotocol Label Switching

Forwarding based on short labels rather than IP lookups. It underpins L3VPNs and traffic engineering in provider networks. Read more

MSS Maximum Segment Size

The largest TCP payload a host will accept, announced in the SYN and SYN-ACK. Routers can lower it ("MSS clamping") so segments fit a smaller path MTU. Read more Learn it in: Packets That Never Come Back

MTU Maximum Transmission Unit

The largest packet an interface can send without fragmenting. In OSPF a mismatch leaves neighbours stuck in ExStart/Exchange. Read more

NAT Network Address Translation

Rewriting addresses as packets pass a router. Source NAT (masquerade) hides private hosts behind the router's address; conntrack remembers each mapping so replies can be translated back. Read more Learn it in: Packets That Never Come Back

NBMA Non-Broadcast Multi-Access

A network where many routers share a medium but broadcast/multicast isn't available (e.g. Frame Relay). OSPF neighbours there must be configured manually. Read more

NDP Neighbor Discovery Protocol

IPv6's replacement for ARP and more: finding neighbours' link-layer addresses, routers (via Router Advertisements) and duplicate addresses, all using ICMPv6. Read more

NEXT_HOP Next hop

BGP attribute giving the IP address to forward traffic to. A path is only valid if the next hop is reachable through the routing table — usually via the IGP. Read more Learn it in: BGP Fundamentals

NLRI Network Layer Reachability Information

The prefixes carried in a BGP UPDATE. The path attributes in the same message describe how to reach them. Read more

NRTM Near Real Time Mirroring

Protocol IRR databases use to stream changes to each other, so mirrors such as RADb stay up to date with the RIR databases. Read more

NSSA Not-So-Stubby Area

An OSPF stub area that may still contain an ASBR. Its external routes travel as Type 7 LSAs and the ABR converts them to Type 5 for the rest of the network. Read more Learn it in: OSPF Fundamentals

NTP Network Time Protocol

Keeps device clocks synchronised (UDP port 123), so logs and timestamps from different devices can be compared. Read more

NXDOMAIN Non-existent domain

The DNS response code meaning the queried name does not exist. A definite answer, unlike SERVFAIL or a timeout. Read more

ORIGIN Origin attribute

BGP attribute recording how a route entered BGP: i (IGP / network statement), e (EGP, historic) or ? (incomplete, e.g. redistributed). Lower is preferred: i < e < ?. Read more Learn it in: BGP Fundamentals

OSPF Open Shortest Path First

The most widely used link-state IGP. Routers flood LSAs to build an identical map of the area, then each runs SPF. OSPFv2 is for IPv4 (RFC 2328), OSPFv3 for IPv6. Read more Learn it in: OSPF Fundamentals

PAT Port Address Translation

The usual form of NAT, where many inside hosts share one public address and the router distinguishes their connections by source port, changing ports when two would clash. Read more

pcap Packet capture file format

The file format written by tcpdump -w and read by tcpdump -r, Wireshark and most analysis tools. Read more

PeeringDB PeeringDB

Public database of networks, IXPs and facilities. Its "IRR as-set/route-set" field is where peers usually find which AS-SET to build your filters from. Read more

PMTUD Path MTU Discovery

Sending packets with Don't Fragment set and lowering their size when a router replies with ICMP "fragmentation needed". Breaks silently if that ICMP is filtered: an MTU black hole. Read more Learn it in: Packets That Never Come Back

PTR Pointer record

The DNS record mapping an address back to a name, stored under in-addr.arpa (IPv4) or ip6.arpa (IPv6). Created by whoever controls the reverse zone; not verified. Read more Learn it in: Linux Network Connectivity

PVID Port VLAN ID

The VLAN that untagged frames arriving on a switch port are placed in. On an access port, it's the port's only VLAN. Read more

QEMU Quick Emulator

Open-source machine emulator and virtualiser. Used in this course to run x86 VyOS as a VM, even on ARM hosts. Read more

RA Router Advertisement

An ICMPv6 message routers send on each LAN, announcing the prefix(es), that they're a default router (and for how long), and optionally DNS servers. Hosts use RAs for SLAAC and their default route. Read more Learn it in: IPv6 on VyOS: setup and routing

RDAP Registration Data Access Protocol

JSON-over-HTTPS successor to whois for registration data (RFC 9082/9083). Routing tools still use whois and IRRd queries for IRR data. Read more

RDNSS Recursive DNS Server option

A Router Advertisement option carrying DNS server addresses, so hosts using SLAAC learn their resolver without DHCPv6. Read more

RFC Request for Comments

The numbered document series that defines internet standards and best practice, published by the IETF. Read more

RIB Routing Information Base

The routing table: every protocol's best routes, from which the router chooses one per prefix (by administrative distance) to program into the FIB. Read more

RIR Regional Internet Registry

One of five organisations (ARIN, RIPE NCC, APNIC, LACNIC, AFRINIC) that allocate IP addresses and ASNs in their region. Read more

ROA Route Origin Authorization

A signed RPKI object stating that one AS may originate a prefix, up to a maximum length. Routes that a ROA covers but does not match are RPKI-invalid. Read more Learn it in: RPKI and Route Origin Validation

ROV Route Origin Validation

Checking each BGP route's origin AS and prefix length against RPKI data (RFC 6811), giving Valid, Invalid or NotFound. Best practice is to drop Invalid. Read more Learn it in: RPKI and Route Origin Validation

rp_filter Reverse-path filtering

A Linux check that drops packets arriving on an interface that isn't the route back to their source. Called source-validation in VyOS. It breaks deliberate asymmetric routing. Read more

RPKI Resource Public Key Infrastructure

Cryptographic certification of who holds which IP space and ASNs. With Route Origin Validation, routers reject BGP routes whose origin AS isn't authorised by a ROA. Read more Learn it in: RPKI and Route Origin Validation

RPSL Routing Policy Specification Language

The text format of IRR data (RFC 2622; IPv6 extensions in RFC 4012): objects made of "attribute: value" lines, separated by blank lines. Read more Learn it in: IRR, RPSL and AS-SETs

RR Route Reflector

An iBGP router allowed to re-advertise iBGP routes to its clients (RFC 4456), removing the need for a full iBGP mesh. Read more Learn it in: BGP Fundamentals

RRDP RPKI Repository Delta Protocol

HTTPS-based protocol (RFC 8182) validators use to fetch RPKI repositories with snapshots and deltas. It replaced rsync as the preferred transport. Read more

RTBH Remotely Triggered Black Hole

Announcing an attacked address (usually a /32) to your provider tagged with the BLACKHOLE community, so the provider drops traffic to it at their edge instead of delivering it to you. Read more Learn it in: BGP communities, prepending and RTBH

RTR RPKI to Router protocol

Simple TCP protocol (RFC 6810, RFC 8210) that validators or caches use to send VRPs to routers incrementally. IANA port 323, often run on a high port. Read more Learn it in: RPKI and Route Origin Validation

SLAAC Stateless Address Autoconfiguration

How IPv6 hosts give themselves addresses: they take the /64 prefix from a Router Advertisement and add their own 64-bit interface identifier. No server keeps track of who has which address. Read more Learn it in: IPv6 on VyOS: setup and routing

SNAT Source NAT

Rewriting the source address (and sometimes port) of outgoing packets, typically so hosts with private addresses can reach the internet using the router's public address. Read more Learn it in: Setting up VyOS with NAT

SNMP Simple Network Management Protocol

A long-standing protocol for polling device counters and status (interfaces, CPU, BGP sessions) from a monitoring system. Read more Learn it in: Operating VyOS: monitoring, backups and automation

SPF Shortest Path First

Dijkstra's algorithm, as run by link-state protocols. Each router computes a tree of lowest-cost paths from itself to every destination using the LSDB. Read more Learn it in: OSPF Fundamentals

SSH Secure Shell

The encrypted protocol (TCP port 22) used to log in to and manage routers, switches and servers remotely. Key-based login is preferred over passwords. Read more Learn it in: Setting up VyOS with basic BGP

STP Spanning Tree Protocol

Finds loops in a switched network and blocks enough ports to break them, preventing broadcast storms. Most managed switches run it (or RSTP/MSTP) by default. Read more

SVI Switched Virtual Interface

A layer 3 interface on a switch for one VLAN, typically the VLAN's default gateway. Lets a layer 3 switch route between VLANs without a separate router. Read more

TAL Trust Anchor Locator

A small file giving the URL and public key of an RPKI trust anchor. Validators ship with one per RIR and verify everything back to them. Read more Learn it in: RPKI and Route Origin Validation

TCG Tiny Code Generator (QEMU)

QEMU's software CPU emulator: it translates a guest's machine code into the host's as it runs, so an x86 VM can run on an ARM Mac. Much slower than hardware virtualisation. Read more Learn it in: Building a network lab on an Apple Silicon Mac

TCP Transmission Control Protocol

Reliable, ordered transport. BGP runs over TCP port 179, so it doesn't need its own retransmission mechanism. Read more

TCP-AO TCP Authentication Option

RFC 5925. Authenticates TCP segments with modern algorithms and key rollover. The successor to TCP-MD5 for protecting BGP sessions. Read more

TCP-MD5 TCP MD5 Signature Option

RFC 2385. Adds a keyed MD5 hash to every TCP segment so that BGP peers can reject spoofed packets. Widely deployed but weak by today's standards. Read more

TTL Time To Live

IP header field decremented by every router; the packet is dropped at zero. eBGP sends with TTL 1 by default, and GTSM uses TTL 255 as a security check. Read more

UDP User Datagram Protocol

Connectionless transport with no delivery guarantees. Unlike BGP, OSPF uses neither TCP nor UDP — it runs directly over IP as protocol 89. Read more

veth Virtual Ethernet pair

Two linked virtual interfaces: whatever enters one comes out of the other. Containers use them to connect their network namespace to a bridge; ip shows them as eth0@ifN. Read more

VLAN Virtual LAN

A separate layer-2 broadcast domain on shared switches, identified by an 802.1Q tag. Hosts in different VLANs need a router to talk. Read more

VNI VXLAN Network Identifier

The 24-bit number identifying a VXLAN segment, like a VLAN ID but with about 16 million values. Read more Learn it in: EVPN and VXLAN: layer 2 over a routed fabric

VPN Virtual Private Network

Private traffic carried across a public network inside an encrypted tunnel, so two sites (or a laptop and an office) behave as if directly connected. Read more Learn it in: Site-to-site VPN with WireGuard on VyOS

VRF Virtual Routing and Forwarding

A separate routing table on one router, keeping networks isolated from each other. The building block of L3VPNs and multi-tenant designs. Read more

VRP Validated ROA Payload

A (prefix, maxLength, origin AS) tuple extracted from a cryptographically verified ROA. Validators send VRPs to routers over RTR. Read more Learn it in: RPKI and Route Origin Validation

VRRP Virtual Router Redundancy Protocol

Lets two or more routers share one virtual gateway IP address on a LAN. One is active; if it fails, another takes over the address, so hosts keep the same default gateway. Read more Learn it in: Office gateway: DHCP, DNS and VRRP on VyOS

VTEP VXLAN Tunnel Endpoint

A switch or host that encapsulates and decapsulates VXLAN traffic, usually using its loopback address. Read more Learn it in: EVPN and VXLAN: layer 2 over a routed fabric

VXLAN Virtual Extensible LAN

Carries Ethernet frames inside UDP (port 4789) across a routed network, so a layer-2 segment can span many switches. Each segment has a 24-bit VNI. Read more Learn it in: EVPN and VXLAN: layer 2 over a routed fabric

VyOS VyOS router OS

An open-source, Debian-based router and firewall OS with a single configuration tree (set/commit), using the Linux kernel, nftables and FRR underneath. Read more Learn it in: Packets That Never Come Back