--- title: On Network Diagrams - ECG description: "Update: This page desperately needed some diagrams. So I've added some. -- Mark, 2008 May 26 I'm a consultant for telcos and ISPs who do VoIP. Nearly all o" --- [![ECG](https://www.ecg.co/hubfs/lp/cloud-migration/logo-vector.svg)](https://www.ecg.co) - Who We Are Company [**About ECG** Learn about the team behind the networks and services that solve real problems.](https://www.ecg.co/about) [**Careers** Join a fun, collaborative, engineer-owned company.](https://www.ecg.co/careers) Industries We Serve [**Enterprises** Optimize multi-site voice networks while meeting compliance requirements.](https://www.ecg.co/sectors/enterprise) [**Universities** Professional services designed for the unique needs of campus networks.](https://www.ecg.co/sectors/universities) [**Government** Engineering services built for government agency voice challenges.](https://www.ecg.co/sectors/government) [**Service Providers** Deep voice expertise to maintain compliance and keep customers connected.](https://www.ecg.co/sectors/service-providers) - Technologies **Carrier & Trunking Services** SIP trunking, resilience & carrier interconnect **Compliance & Call Authentication** STIR/SHAKEN, 603+ & secure signaling **Unified Communications & Collaboration** UC capabilities & platform expertise **Platform Reliability & Security** Infrastructure, capture & network fundamentals ### Carrier & Trunking Services Design, harden, and secure the carrier side of your voice network — from SIP trunking to encrypted media and compliant recording. [SIP Trunking](https://www.ecg.co/technologies/sip-trunking-consulting-expertise) [SIP Trunking High Availability](https://www.ecg.co/technologies/sip-trunking-high-availability) [STIR/SHAKEN](https://www.ecg.co/technologies/stir-shaken) [603+](https://www.ecg.co/technologies/603-plus-do-not-originate) [eSIM & FMC](https://www.ecg.co/technologies/esim-fmc) [VoIP TLS & SRTP](https://www.ecg.co/technologies/voip-encryption-tls-srtp) [SIPREC](https://www.ecg.co/technologies/siprec-call-recording) ### Compliance & Call Authentication Meet regulatory requirements end-to-end — call authentication, robocall mitigation, lawful capture, and encrypted signaling. [STIR/SHAKEN](https://www.ecg.co/technologies/stir-shaken) [603+](https://www.ecg.co/technologies/603-plus-do-not-originate) [Packet Capture / PCAP](https://www.ecg.co/technologies/pcap-wireshark-packet-capture-analysis) [VoIP TLS & SRTP](https://www.ecg.co/technologies/voip-encryption-tls-srtp) ### Unified Communications & Collaboration Modern UC capabilities backed by deep, hands-on expertise across every major voice platform. [E911](https://www.ecg.co/technologies/e911) [Business Texting](https://www.ecg.co/technologies/business-texting) [Teams Replace Phone System](https://www.ecg.co/technologies/ms-teams-replace-phone-system) [Provisioning & Endpoint Mgmt](https://www.ecg.co/technologies/sip-provisioning-endpoint-management) [Call Control & Features](https://www.ecg.co/technologies/call-control-features) [SIP Trunking HA](https://www.ecg.co/technologies/sip-trunking-high-availability) [SIPREC](https://www.ecg.co/technologies/siprec-call-recording) [vCon](https://www.ecg.co/technologies/vcon-virtualized-conversations) Platform Expertise [BroadWorks](https://www.ecg.co/technologies/broadworks) [NetSapiens](https://www.ecg.co/technologies/netsapiens-support) [Metaswitch Alianza Core](https://www.ecg.co/technologies/metaswitch-alianza-core) [Oracle Communications](https://www.ecg.co/technologies/oracle-communications-support) [Metaswitch Perimeta](https://www.ecg.co/technologies/metaswitch-perimeta) [Sansay VSXi](https://www.ecg.co/sansay-vsxi-session-border-controller) ### Platform Reliability & Security The infrastructure layer underneath your voice services — engineered, monitored, and secured by people who run it every day. [EKS / Kubernetes](https://www.ecg.co/technologies/kubernetes-eks) [Critical Network Fundamentals](https://www.ecg.co/technologies/critical-network-fundamentals) [Packet Capture / PCAP](https://www.ecg.co/technologies/pcap-wireshark-packet-capture-analysis) [VMware & Alternatives](https://www.ecg.co/technologies/vmware-alternatives) [Routing, Switching & Firewalls](https://www.ecg.co/technologies/routing-switching-firewalls) [Freeswitch](https://www.ecg.co/technologies/freeswitch-open-source-call-processing) - How We Do It Services [**Services Overview** Our experience and expertise in voice and data engineering.](https://www.ecg.co/services) [**Network Operations** Keep your voice network running with outsourced network operations.](https://www.ecg.co/services/network-operations) [**Staff Augmentation** Expert engineering support to meet deadlines and fill knowledge gaps.](https://www.ecg.co/services/staff-augmentation) [**IT Consulting & Engineering** Complete short-term projects faster with a dedicated project manager.](https://www.ecg.co/services/it-consulting-and-engineering) - Resources #### [Utilities Launch Delay Calculator Estimate what a potential product launch delay would cost your business. Try the calculator](https://www.ecg.co/cost-delay-calculator) #### [Resource Library Guides, White Papers & Tools In-depth resources on voice engineering, compliance, and AI — built from real client work. Explore resources](https://www.ecg.co/resource-library) #### [Blog Latest from the ECG Team Practical articles on SIP, UC platforms, network operations, and voice AI. Read the blog](https://www.ecg.co/blog) - [Events](https://www.ecg.co/events) [Login](https://portal.ecg.co) [Contact](https://www.ecg.co/contact) Who We Are [About ECG](https://www.ecg.co/about) [Careers](https://www.ecg.co/careers) Industries We Serve [Enterprises](https://www.ecg.co/sectors/enterprise) [Universities](https://www.ecg.co/sectors/universities) [Government](https://www.ecg.co/sectors/government) [Service Providers](https://www.ecg.co/sectors/service-providers) Technologies Carrier & Trunking Services [SIP Trunking](https://www.ecg.co/technologies/sip-trunking-consulting-expertise) [SIP Trunking High Availability](https://www.ecg.co/technologies/sip-trunking-high-availability) [STIR/SHAKEN](https://www.ecg.co/technologies/stir-shaken) [603+](https://www.ecg.co/technologies/603-plus-do-not-originate) [eSIM & FMC](https://www.ecg.co/technologies/esim-fmc) [VoIP TLS & SRTP](https://www.ecg.co/technologies/voip-encryption-tls-srtp) [SIPREC](https://www.ecg.co/technologies/siprec-call-recording) Compliance & Call Authentication [STIR/SHAKEN](https://www.ecg.co/technologies/stir-shaken) [603+](https://www.ecg.co/technologies/603-plus-do-not-originate) [Packet Capture / PCAP](https://www.ecg.co/technologies/pcap-wireshark-packet-capture-analysis) [VoIP TLS & SRTP](https://www.ecg.co/technologies/voip-encryption-tls-srtp) Unified Communications & Collaboration [E911](https://www.ecg.co/technologies/e911) [Business Texting](https://www.ecg.co/technologies/business-texting) [Teams Replace Phone System](https://www.ecg.co/technologies/ms-teams-replace-phone-system) [Provisioning & Endpoint Mgmt](https://www.ecg.co/technologies/sip-provisioning-endpoint-management) [Call Control & Features](https://www.ecg.co/technologies/call-control-features) [SIP Trunking HA](https://www.ecg.co/technologies/sip-trunking-high-availability) [SIPREC](https://www.ecg.co/technologies/siprec-call-recording) [vCon](https://www.ecg.co/technologies/vcon-virtualized-conversations) Platform Expertise [BroadWorks](https://www.ecg.co/technologies/broadworks) [NetSapiens](https://www.ecg.co/technologies/netsapiens-support) [Metaswitch Alianza Core](https://www.ecg.co/technologies/metaswitch-alianza-core) [Oracle Communications](https://www.ecg.co/technologies/oracle-communications-support) [Metaswitch Perimeta](https://www.ecg.co/technologies/metaswitch-perimeta) [Sansay VSXi](https://www.ecg.co/sansay-vsxi-session-border-controller) Platform Reliability & Security [EKS / Kubernetes](https://www.ecg.co/technologies/kubernetes-eks) [Critical Network Fundamentals](https://www.ecg.co/technologies/critical-network-fundamentals) [Packet Capture / PCAP](https://www.ecg.co/technologies/pcap-wireshark-packet-capture-analysis) [VMware & Alternatives](https://www.ecg.co/technologies/vmware-alternatives) [Routing, Switching & Firewalls](https://www.ecg.co/technologies/routing-switching-firewalls) [Freeswitch](https://www.ecg.co/technologies/freeswitch-open-source-call-processing) How We Do It Services [Services Overview](https://www.ecg.co/services) [Network Operations](https://www.ecg.co/services/network-operations) [Staff Augmentation](https://www.ecg.co/services/staff-augmentation) [IT Consulting & Engineering](https://www.ecg.co/services/it-consulting-and-engineering) Resources [Launch Delay Calculator](https://www.ecg.co/cost-delay-calculator) [Guides, White Papers & Tools](https://www.ecg.co/resource-library) [Latest from the ECG Team](https://www.ecg.co/blog) [Events](https://www.ecg.co/events) [Login](https://portal.ecg.co) [Contact](https://www.ecg.co/contact) # On Network Diagrams By: Mark Lindsey 3 min read Dec 10, 2007 Update: This page desperately needed some diagrams. So I've added some. -- Mark, 2008 May 26 I'm a consultant for telcos and ISPs who do VoIP. Nearly all of my customers have diagrams. They're always Visio. We use their diagrams to help do network design changes or troubleshooting. At nearly every customer, as we start studying their diagrams in detail, they'll say, "wait, that's not right. This doesn't even show the FL-2100 we installed two years ago!" Or "no, there must be more cables than this. There's no way this is right." However, I still learn things from the diagrams, especially when I have commentary to help understand. And anything that's important must be re-checked. --- ### Physical Layer Diagrams [![](https://www.ecg.co/hubfs/Imported_Blog_Media/missing-image-Mar-25-2024-07-07-22-4234-AM.png)](https://www.ecg.co/hubfs/Imported_Blog_Media/simple_physical_net_diagram-2-1.png) Nearly everybody maintains \*physical layer\* diagrams; i.e., each box on the diagram represents a physical device, and each line represents a cable. Physical diagrams are nice, especially for troubleshooting wholesale outages, or counting available ports, or designing fault tolerance. And they're fine for 1994-era IP networking -- all hubs, no VLANs, one IP address per device. But physical diagrams strain to convey: VLANs. Which VLAN is this port assigned to? Is it a VLAN trunk? Subnets. What subnet is this device a member of? Roles. Which devices are doing routing? Switching? Basic servers? Multiple IP routing tables per device. E.g., Cisco VRFs / MPLS VPNs. Devices with numerous IP addresses within each IP stack. Visio users like to insert little pictures of the actual equipment. I don't do that; at best it's just pretty, and at worst it's distracting and doesn't print well. [![](https://www.ecg.co/hubfs/Imported_Blog_Media/example_physical_diagram_1-2-1.png)](https://www.ecg.co/hubfs/Imported_Blog_Media/example_physical_diagram_1-3-1.png) --- ### VLAN/Subnet Diagrams (Or, "how do i represent vlans on a network diagram?") [![](https://www.ecg.co/hubfs/Imported_Blog_Media/simple_l3_diagram-3-1.png)](https://www.ecg.co/hubfs/Imported_Blog_Media/simple_l3_diagram-2-1.png) [![](https://www.ecg.co/hubfs/Imported_Blog_Media/example_vlan_subnet_diagram-2-1.png)](https://www.ecg.co/hubfs/Imported_Blog_Media/example_vlan_subnet_diagram-3-1.png) VLAN/Subnet diagrams are what's needed. In this form, each box represents a VRF or IP routing table -- typically one per physical device. Each line represents an IP address assignment to a subnet. And at the center, we have some other shape, like an oval, to represent the actual subnets (or collision domains, if you'd like). In clean designs, one subnet is exactly one VLAN. We usually do not actually draw Layer-2 switching equipment in. VLAN/Subnet diagrams are great for following the paths of packets through the network. VLAN/Subnet diagrams of this form have their limitations, too: No good at representing layer-2 redundancy Not good at identifying available ports. Not good for inventory; not every physical device is shown They don't show what data flow is normal or expected. More tricks are needed when VRFs are involved. An alternate approach is to representing VLANs is to color-code the cables on a physical diagram. A blue cable is VLAN 101, a red cable is VLAN 102, a green cable is VLAN 103. This certainly can work as long as your number of VLANs is relatively small. ("Wait, which VLAN is magenta, and which is purple?") --- ### Application-Layer Communication There's yet another valuable abstraction for diagramming networks: Application-layer communication diagrams. These are much like UML Communication diagrams. Here, we don't show any underlying transport, but only the normal communication paths at the Application layer. For any given device X, there's a line drawn to every device Y where X and Y communicate at the application layer. This type is absolutely essential for developing effective firewall and IDS rules. It's also valuable for SIP VoIP platforms, where routing of SIP messages is complex and where it's reasonable to ask, "Where \*should\* this device be sending its INVITE? To what other devices will it be sending RTP?" [![](https://www.ecg.co/hubfs/Imported_Blog_Media/application_communication_diagram_1-3-1.png)](https://www.ecg.co/hubfs/Imported_Blog_Media/application_communication_diagram_1-2-1.png) ![](https://www.ecg.co/hs-fs/hubfs/Imported_Blog_Media/missing-image-Mar-25-2024-07-07-22-4234-AM.png?width=1&height=1&name=missing-image-Mar-25-2024-07-07-22-4234-AM.png) ## Similar posts [![Flooding packets for VoIP testing](https://www.ecg.co/hubfs/ecg-site/blog-listing-placeholder.jpg)](https://www.ecg.co/blog/38-flooding-packets-for-voip-testing) ### [Flooding packets for VoIP testing](https://www.ecg.co/blog/38-flooding-packets-for-voip-testing) [![Work Flows Up: Effectively Distributing Work on a Team of Engineers](https://www.ecg.co/hubfs/Imported_Blog_Media/regular_4454497924_202f4e6747_o_smaller-1.jpg)](https://www.ecg.co/blog/120-work-flows-up-effectively-distributing-work-on-a-team-of-engineers) ### [Work Flows Up: Effectively Distributing Work on a Team of Engineers](https://www.ecg.co/blog/120-work-flows-up-effectively-distributing-work-on-a-team-of-engineers) [![Writing Detailed MOPs, and the Distinction between Planning and Doing](https://www.ecg.co/hubfs/ecg-site/blog-listing-placeholder.jpg)](https://www.ecg.co/blog/57-writing-detailed-mops-and-the-distinction-between-planning-and-doing) ### [Writing Detailed MOPs, and the Distinction between Planning and Doing](https://www.ecg.co/blog/57-writing-detailed-mops-and-the-distinction-between-planning-and-doing) ## Need Help With Your Network or AI Project? Get expert advice from engineers who've solved complex problems for carriers, enterprises, and government agencies. [Let's Talk](https://www.ecg.co/contact) [![ecg-logo-white](https://www.ecg.co/hubfs/ecg-site/global/ecg-logo-white.svg "ecg-logo-white")](https://www.ecg.co/) 505 North Toombs St. Suite A Valdosta, Georgia 31601 USA #### Headquarters - 1.866.324.0700 US Toll-free - 1.229.244.2099 International - 1.229.244.2399 Fax - [info@e-c-group.com](mailto:info@e-c-group.com) #### Services - [Overview](https://www.ecg.co/services) - [Network Operations](https://www.ecg.co/services/network-operations) - [Custom AI Development](https://www.ecg.co/services/custom-ai-development) - [Outsourced NOC Support](https://www.ecg.co/services/outsourced-noc-support) - [Staff Augmentation](https://www.ecg.co/services/staff-augmentation) - [IT Consulting & Engineering](https://www.ecg.co/services/it-consulting-and-engineering) #### Company - [About](https://www.ecg.co/about) - [Careers](https://www.ecg.co/careers) - [Blog](https://www.ecg.co/blog) - [Resources](https://www.ecg.co/resource-library) - [Events](https://www.ecg.co/events) © ECG, Inc. [Privacy Policy](https://9353907.hs-sites.com/privacy) ```json { "@context" : "https://schema.org", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "Mark Lindsey", "url" : "https://www.ecg.co/blog/author/mark-lindsey" }, "dateModified" : "2024-03-25T07:09:15.895Z", "datePublished" : "2007-12-10T05:00:00.000Z", "headline" : "On Network Diagrams - ECG", "mainEntityOfPage" : { "@id" : "https://www.ecg.co/blog/36-on-network-diagrams", "@type" : "WebPage" }, "publisher" : { "@type" : "Organization", "logo" : { "@type" : "ImageObject", "url" : "https://www.ecg.co/hubfs/ECG_hexagons_and_url_borderless.jpeg" }, "name" : "ECG, Inc" } } ```