{"id":3428,"date":"2026-10-27T12:56:22","date_gmt":"2026-10-27T19:56:22","guid":{"rendered":"https:\/\/cyber.mag212.com\/learn\/interior-routing-protocols\/"},"modified":"2026-10-27T12:56:22","modified_gmt":"2026-10-27T19:56:22","slug":"interior-routing-protocols","status":"publish","type":"page","link":"https:\/\/cyber.mag212.com\/fr\/learn\/interior-routing-protocols\/","title":{"rendered":"Interior Routing Protocols Compared"},"content":{"rendered":"<style>.m212ig{background:#07111C;color:#eaf3f8;font:16px\/1.68 system-ui,Arial,sans-serif;border:1px solid #1f3b4d;border-radius:14px;overflow:hidden}\n.m212ig *{box-sizing:border-box}\n.m212ig .ig-hero{padding:38px 28px;background:linear-gradient(120deg,#10263b,#07111C);border-bottom:5px solid #46DB82}\n.m212ig .brand{font-weight:900;font-size:24px;letter-spacing:3px}.m212ig .brand em{color:#46DB82;font-style:normal}\n.m212ig .eyebrow{color:#3CC8E8;letter-spacing:3px;text-transform:uppercase;font-size:12px}\n.m212ig .ig-title{font-size:clamp(30px,5vw,52px);line-height:1.12;margin:12px 0;color:#fff;border:0;padding:0}\n.m212ig .ig-main{padding:6px 22px 20px}\n.m212ig h2{font-size:26px;color:#46DB82;margin:0 0 8px;border:0;padding:0}\n.m212ig .ig-sec{background:#122439;border:1px solid #2b4d64;border-radius:16px;margin:25px 0;padding:26px;scroll-margin-top:110px}\n.m212ig p{margin:9px 0 16px;color:#eaf3f8}\n.m212ig .description{color:#9FB3C5}\n.m212ig pre{background:#07111C;border:0;border-left:4px solid #3CC8E8;padding:18px;white-space:pre-wrap;overflow-wrap:anywhere;border-radius:10px;color:#d5f5e3;font:13.5px\/1.55 ui-monospace,Consolas,monospace;margin:8px 0 14px}\n.m212ig pre code{color:#d5f5e3;background:none;padding:0}\n.m212ig code{color:#9cebd3;font-family:ui-monospace,Consolas,monospace}\n.m212ig table{border-collapse:collapse;width:100%;font-size:14px;line-height:1.5;margin:10px 0}\n.m212ig td,.m212ig th{padding:10px;border:1px solid #365066;text-align:left;vertical-align:top;color:#eaf3f8}\n.m212ig th{background:#15516b;color:#fff}\n.m212ig figure{margin:15px 0;background:#07111C;padding:0;border-radius:16px}.m212ig figure svg{width:100%;height:auto;display:block;border-radius:14px;border:1px solid #2b4d64}\n.m212ig figcaption{color:#9FB3C5;font-size:13px;margin-top:8px}\n.m212ig ol,.m212ig ul{padding-left:22px;margin:10px 0}.m212ig li{margin-bottom:8px}\n.m212ig .qa{background:#10293a;padding:12px 18px;border-left:3px solid #46DB82;margin:10px 0;border-radius:6px}.m212ig .qa p{margin:4px 0 0}\n.m212ig a{color:#3CC8E8}\n.m212ig .ig-dl{display:inline-block;margin-top:8px;background:#46db82;color:#04130c;font-weight:800;text-decoration:none;border-radius:8px;padding:11px 18px}\n.m212ig .ig-foot{padding:24px;text-align:center;color:#9FB3C5;font-size:14px;border-top:1px solid #244052}\n@media(max-width:620px){.m212ig .ig-hero{padding:26px 18px}.m212ig .ig-main{padding:4px 10px 14px}.m212ig .ig-sec{padding:16px}.m212ig table{font-size:12.5px}}<\/style>\n<div class=\"m212ig\" id=\"m212-igp\"><div class=\"ig-hero\"><div class=\"brand\">MAG212 <em>CYBER<\/em><\/div><div class=\"eyebrow\">Network engineering field guide \u00b7 October 2026<\/div><h2 class=\"ig-title\">Interior Routing Protocols<br\/>Ultimate Cheat Sheet<\/h2><p>RIP \u00b7 EIGRP \u00b7 OSPF \u00b7 IS-IS | Configuration, Commands, Troubleshooting &amp; Security<\/p><p>Published by MAG212 CYBER \u00b7 Technical learning series<\/p><a class=\"ig-dl\" href=\"https:\/\/cyber.mag212.com\/wp-content\/uploads\/2026\/10\/MAG212_CYBER_Interior_Routing_Cheat_Sheet.pdf\" target=\"_blank\" rel=\"noopener\">\u2b07 T\u00e9l\u00e9charger l&#039;\u00e9dition PDF<\/a><\/div><div class=\"ig-main\">\n<figure><svg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 1800 1120\" role=\"img\" aria-labelledby=\"igT igD\"><title id=\"igT\">Four-router interior routing lab topology<\/title><desc id=\"igD\">R1, R2 and R3 form a triangle in OSPF Area 0. R3 connects to R4 in OSPF Area 10, making R3 the ABR. R1 and R4 each have a user LAN behind an access switch.<\/desc><defs><lineargradient id=\"igbg\" x2=\"1\" y2=\"1\"><stop stop-color=\"#05121e\"\/><stop offset=\"1\" stop-color=\"#0f2a3d\"\/><\/lineargradient><lineargradient id=\"igrt\" x2=\"0\" y2=\"1\"><stop stop-color=\"#5ca6c5\"\/><stop offset=\"1\" stop-color=\"#126181\"\/><\/lineargradient><\/defs><rect width=\"1800\" height=\"1120\" fill=\"url(#igbg)\"\/><g stroke=\"#1f3d52\" opacity=\".45\"><path d=\"M0 0V1120\"\/><path d=\"M50 0V1120\"\/><path d=\"M100 0V1120\"\/><path d=\"M150 0V1120\"\/><path d=\"M200 0V1120\"\/><path d=\"M250 0V1120\"\/><path d=\"M300 0V1120\"\/><path d=\"M350 0V1120\"\/><path d=\"M400 0V1120\"\/><path d=\"M450 0V1120\"\/><path d=\"M500 0V1120\"\/><path d=\"M550 0V1120\"\/><path d=\"M600 0V1120\"\/><path d=\"M650 0V1120\"\/><path d=\"M700 0V1120\"\/><path d=\"M750 0V1120\"\/><path d=\"M800 0V1120\"\/><path d=\"M850 0V1120\"\/><path d=\"M900 0V1120\"\/><path d=\"M950 0V1120\"\/><path d=\"M1000 0V1120\"\/><path d=\"M1050 0V1120\"\/><path d=\"M1100 0V1120\"\/><path d=\"M1150 0V1120\"\/><path d=\"M1200 0V1120\"\/><path d=\"M1250 0V1120\"\/><path d=\"M1300 0V1120\"\/><path d=\"M1350 0V1120\"\/><path d=\"M1400 0V1120\"\/><path d=\"M1450 0V1120\"\/><path d=\"M1500 0V1120\"\/><path d=\"M1550 0V1120\"\/><path d=\"M1600 0V1120\"\/><path d=\"M1650 0V1120\"\/><path d=\"M1700 0V1120\"\/><path d=\"M1750 0V1120\"\/><path d=\"M1800 0V1120\"\/><path d=\"M0 0H1800\"\/><path d=\"M0 50H1800\"\/><path d=\"M0 100H1800\"\/><path d=\"M0 150H1800\"\/><path d=\"M0 200H1800\"\/><path d=\"M0 250H1800\"\/><path d=\"M0 300H1800\"\/><path d=\"M0 350H1800\"\/><path d=\"M0 400H1800\"\/><path d=\"M0 450H1800\"\/><path d=\"M0 500H1800\"\/><path d=\"M0 550H1800\"\/><path d=\"M0 600H1800\"\/><path d=\"M0 650H1800\"\/><path d=\"M0 700H1800\"\/><path d=\"M0 750H1800\"\/><path d=\"M0 800H1800\"\/><path d=\"M0 850H1800\"\/><path d=\"M0 900H1800\"\/><path d=\"M0 950H1800\"\/><path d=\"M0 1000H1800\"\/><path d=\"M0 1050H1800\"\/><path d=\"M0 1100H1800\"\/><\/g><text x=\"60\" y=\"70\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"42\" font-weight=\"900\" fill=\"#46db82\">MAG212 CYBER<\/text><text x=\"460\" y=\"70\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"34\" font-weight=\"800\" fill=\"#e3f4fc\">\u00b7 INTERIOR ROUTING LAB<\/text><text x=\"62\" y=\"106\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"20\" fill=\"#9cc3d9\">One physical topology \u00b7 configure RIP, EIGRP, OSPF or IS-IS separately \u00b7 areas shown for the OSPF lab<\/text><rect x=\"60\" y=\"140\" width=\"1170\" height=\"640\" rx=\"24\" fill=\"#0b2335\" fill-opacity=\".7\" stroke=\"#3cc8e8\" stroke-width=\"3\" stroke-dasharray=\"14 9\"\/><text x=\"90\" y=\"185\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"26\" font-weight=\"800\" fill=\"#3cc8e8\">OSPF AREA 0 \u00b7 BACKBONE<\/text><rect x=\"1290\" y=\"140\" width=\"450\" height=\"640\" rx=\"24\" fill=\"#0b2a22\" fill-opacity=\".6\" stroke=\"#46db82\" stroke-width=\"3\" stroke-dasharray=\"14 9\"\/><text x=\"1515\" y=\"185\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"26\" font-weight=\"800\" fill=\"#46db82\" text-anchor=\"middle\">OSPF AREA 10 \u00b7 BRANCH<\/text><path d=\"M300 500L680 300\" stroke=\"#3cc8e8\" stroke-width=\"10\" stroke-linecap=\"round\"\/><path d=\"M680 300L1060 500\" stroke=\"#3cc8e8\" stroke-width=\"10\" stroke-linecap=\"round\"\/><path d=\"M300 500L1060 500\" stroke=\"#3cc8e8\" stroke-width=\"10\" stroke-linecap=\"round\"\/><path d=\"M1060 500L1515 500\" stroke=\"#46db82\" stroke-width=\"10\" stroke-linecap=\"round\"\/><rect x=\"327.5\" y=\"357.0\" width=\"285.0\" height=\"62\" rx=\"10\" fill=\"#0a1f2f\" stroke=\"#3d6a84\"\/><text x=\"470\" y=\"382\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"700\" fill=\"#e3f4fc\" text-anchor=\"middle\">10.10.12.0\/30<\/text><text x=\"470\" y=\"406\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"16\" fill=\"#a9c7d8\" text-anchor=\"middle\">R1 Gi0\/0 .1 \u2194 R2 Gi0\/0 .2<\/text><rect x=\"747.5\" y=\"357.0\" width=\"285.0\" height=\"62\" rx=\"10\" fill=\"#0a1f2f\" stroke=\"#3d6a84\"\/><text x=\"890\" y=\"382\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"700\" fill=\"#e3f4fc\" text-anchor=\"middle\">10.10.23.0\/30<\/text><text x=\"890\" y=\"406\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"16\" fill=\"#a9c7d8\" text-anchor=\"middle\">R2 Gi0\/1 .1 \u2194 R3 Gi0\/0 .2<\/text><rect x=\"537.5\" y=\"469.0\" width=\"285.0\" height=\"62\" rx=\"10\" fill=\"#0a1f2f\" stroke=\"#3d6a84\"\/><text x=\"680\" y=\"494\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"700\" fill=\"#e3f4fc\" text-anchor=\"middle\">10.10.13.0\/30<\/text><text x=\"680\" y=\"518\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"16\" fill=\"#a9c7d8\" text-anchor=\"middle\">R1 Gi0\/1 .1 \u2194 R3 Gi0\/1 .2<\/text><rect x=\"1145.5\" y=\"469.0\" width=\"285.0\" height=\"62\" rx=\"10\" fill=\"#0a1f2f\" stroke=\"#2f7d58\"\/><text x=\"1288\" y=\"494\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"700\" fill=\"#e3f4fc\" text-anchor=\"middle\">10.10.34.0\/30<\/text><text x=\"1288\" y=\"518\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"16\" fill=\"#a9c7d8\" text-anchor=\"middle\">R3 Gi0\/2 .1 \u2194 R4 Gi0\/0 .2<\/text><ellipse cx=\"300\" cy=\"520\" rx=\"60\" ry=\"22\" fill=\"#0d3a50\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><rect x=\"240\" y=\"480\" width=\"120\" height=\"40\" fill=\"url(#igrt)\"\/><path d=\"M240 480V520M360 480V520\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><ellipse cx=\"300\" cy=\"480\" rx=\"60\" ry=\"22\" fill=\"#4f9dbd\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><g stroke=\"#effaff\" stroke-width=\"3\" fill=\"none\" stroke-linecap=\"round\"><path d=\"M266 474h22m-6 -5l6 5l-6 5\"\/><path d=\"M312 474h22m-6 -5l6 5l-6 5\"\/><path d=\"M290 488h20m-6 -5l6 5l-6 5\"\/><\/g><ellipse cx=\"680\" cy=\"320\" rx=\"60\" ry=\"22\" fill=\"#0d3a50\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><rect x=\"620\" y=\"280\" width=\"120\" height=\"40\" fill=\"url(#igrt)\"\/><path d=\"M620 280V320M740 280V320\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><ellipse cx=\"680\" cy=\"280\" rx=\"60\" ry=\"22\" fill=\"#4f9dbd\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><g stroke=\"#effaff\" stroke-width=\"3\" fill=\"none\" stroke-linecap=\"round\"><path d=\"M646 274h22m-6 -5l6 5l-6 5\"\/><path d=\"M692 274h22m-6 -5l6 5l-6 5\"\/><path d=\"M670 288h20m-6 -5l6 5l-6 5\"\/><\/g><ellipse cx=\"1060\" cy=\"520\" rx=\"60\" ry=\"22\" fill=\"#0d3a50\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><rect x=\"1000\" y=\"480\" width=\"120\" height=\"40\" fill=\"url(#igrt)\"\/><path d=\"M1000 480V520M1120 480V520\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><ellipse cx=\"1060\" cy=\"480\" rx=\"60\" ry=\"22\" fill=\"#4f9dbd\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><g stroke=\"#effaff\" stroke-width=\"3\" fill=\"none\" stroke-linecap=\"round\"><path d=\"M1026 474h22m-6 -5l6 5l-6 5\"\/><path d=\"M1072 474h22m-6 -5l6 5l-6 5\"\/><path d=\"M1050 488h20m-6 -5l6 5l-6 5\"\/><\/g><ellipse cx=\"1515\" cy=\"520\" rx=\"60\" ry=\"22\" fill=\"#0d3a50\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><rect x=\"1455\" y=\"480\" width=\"120\" height=\"40\" fill=\"url(#igrt)\"\/><path d=\"M1455 480V520M1575 480V520\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><ellipse cx=\"1515\" cy=\"480\" rx=\"60\" ry=\"22\" fill=\"#4f9dbd\" stroke=\"#9fe6ff\" stroke-width=\"3\"\/><g stroke=\"#effaff\" stroke-width=\"3\" fill=\"none\" stroke-linecap=\"round\"><path d=\"M1481 474h22m-6 -5l6 5l-6 5\"\/><path d=\"M1527 474h22m-6 -5l6 5l-6 5\"\/><path d=\"M1505 488h20m-6 -5l6 5l-6 5\"\/><\/g><text x=\"680\" y=\"204\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"30\" font-weight=\"800\" fill=\"#fff\" text-anchor=\"middle\">R2 \u00b7 Core<\/text><text x=\"680\" y=\"230\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"17\" fill=\"#8fd8a9\" text-anchor=\"middle\">Lo0 2.2.2.2\/32<\/text><text x=\"220\" y=\"494\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"30\" font-weight=\"800\" fill=\"#fff\" text-anchor=\"end\">R1<\/text><text x=\"220\" y=\"520\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"17\" fill=\"#8fd8a9\" text-anchor=\"end\">Lo0 1.1.1.1\/32<\/text><text x=\"1060\" y=\"580\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"30\" font-weight=\"800\" fill=\"#fff\" text-anchor=\"middle\">R3 \u00b7 ABR<\/text><text x=\"1060\" y=\"606\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"17\" fill=\"#8fd8a9\" text-anchor=\"middle\">Lo0 3.3.3.3\/32<\/text><text x=\"1515\" y=\"404\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"30\" font-weight=\"800\" fill=\"#fff\" text-anchor=\"middle\">R4 \u00b7 Branch<\/text><text x=\"1515\" y=\"430\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"17\" fill=\"#8fd8a9\" text-anchor=\"middle\">Lo0 4.4.4.4\/32<\/text><path d=\"M300 544V618\" stroke=\"#46db82\" stroke-width=\"6\"\/><path d=\"M232 620h96l20 22h-96z\" fill=\"#2c7ea2\" stroke=\"#9fe6ff\" stroke-width=\"2.5\"\/><rect x=\"252\" y=\"642\" width=\"96\" height=\"30\" fill=\"#155a78\" stroke=\"#9fe6ff\" stroke-width=\"2.5\"\/><rect x=\"260\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"275\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"290\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"305\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"320\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"335\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><text x=\"300\" y=\"710\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"19\" font-weight=\"700\" fill=\"#e3f4fc\" text-anchor=\"middle\">User LAN \u00b7 172.16.10.0\/24<\/text><text x=\"300\" y=\"736\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"16\" fill=\"#a9c7d8\" text-anchor=\"middle\">R1 Gi0\/2 \u00b7 172.16.10.1 (gateway)<\/text><path d=\"M1515 544V618\" stroke=\"#46db82\" stroke-width=\"6\"\/><path d=\"M1447 620h96l20 22h-96z\" fill=\"#2c7ea2\" stroke=\"#9fe6ff\" stroke-width=\"2.5\"\/><rect x=\"1467\" y=\"642\" width=\"96\" height=\"30\" fill=\"#155a78\" stroke=\"#9fe6ff\" stroke-width=\"2.5\"\/><rect x=\"1475\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"1490\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"1505\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"1520\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"1535\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><rect x=\"1550\" y=\"654\" width=\"9\" height=\"6\" fill=\"#46db82\"\/><text x=\"1515\" y=\"710\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"19\" font-weight=\"700\" fill=\"#e3f4fc\" text-anchor=\"middle\">User LAN \u00b7 172.16.40.0\/24<\/text><text x=\"1515\" y=\"736\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"16\" fill=\"#a9c7d8\" text-anchor=\"middle\">R4 Gi0\/1 \u00b7 172.16.40.1 (gateway)<\/text><rect x=\"60\" y=\"815\" width=\"1680\" height=\"210\" rx=\"14\" fill=\"#0a1f2f\" stroke=\"#3d6a84\"\/><text x=\"90\" y=\"858\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"22\" font-weight=\"800\" fill=\"#e3f4fc\">PROTOCOL OVERLAYS \u00b7 run one protocol at a time<\/text><text x=\"90\" y=\"896\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"800\" fill=\"#46db82\">RIPv2<\/text><text x=\"200\" y=\"896\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" fill=\"#cfe4ef\">network 10.0.0.0 on every router; network 172.16.0.0 on R1 and R4; LAN interfaces passive<\/text><text x=\"90\" y=\"928\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"800\" fill=\"#46db82\">EIGRP<\/text><text x=\"200\" y=\"928\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" fill=\"#cfe4ef\">AS 100 on all four transit links; DUAL keeps a feasible successor where the feasibility condition holds<\/text><text x=\"90\" y=\"960\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"800\" fill=\"#46db82\">OSPF<\/text><text x=\"200\" y=\"960\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" fill=\"#cfe4ef\">Area 0: R1\u2013R2, R2\u2013R3, R1\u2013R3 and R1 LAN \u00b7 Area 10: R3\u2013R4 and R4 LAN \u00b7 R3 is the ABR<\/text><text x=\"90\" y=\"992\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" font-weight=\"800\" fill=\"#46db82\">EST-EST<\/text><text x=\"200\" y=\"992\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"18\" fill=\"#cfe4ef\">R1, R2, R3 in area 49.0001 \u00b7 R4 in area 49.0002 \u00b7 R3\u2013R4 forms a Level-2 adjacency only<\/text><text x=\"60\" y=\"1080\" font-family=\"DejaVu Sans,Arial,sans-serif\" font-size=\"16\" fill=\"#8fb3c6\">Illustrative Cisco-inspired stencils, not official Cisco assets \u00b7 Gi = GigabitEthernet \u00b7 all addresses are lab examples<\/text><\/svg><figcaption>One physical topology for four separate labs. Interface names and addresses match section 02; the OSPF areas shown apply to the OSPF lab. Run one routing protocol at a time and avoid mixing them in one routing domain.<\/figcaption><\/figure>\n<div class=\"ig-sec\" id=\"section-1\"><div class=\"eyebrow\">Field guide \/ 01<\/div><h2>Quick reference: protocols compared<\/h2><p class=\"description\">Understand the design decision before typing commands.<\/p><div style=\"overflow-x:auto\"><table>\n<tr><th>Protocole<\/th><th>Algorithm<\/th><th>AD (Cisco defaults)<\/th><th>M\u00e9trique<\/th><th>Transport<\/th><th>Best fit<\/th><\/tr>\n<tr><td>RIPv2<\/td><td>Bellman-Ford<\/td><td>120<\/td><td>Hop count, max 15<\/td><td>UDP 520<\/td><td>Legacy labs<\/td><\/tr>\n<tr><td>RIPng<\/td><td>Bellman-Ford<\/td><td>120<\/td><td>Hop count, max 15<\/td><td>UDP 521<\/td><td>Legacy IPv6 labs<\/td><\/tr>\n<tr><td>EIGRP<\/td><td>DUAL<\/td><td>90 internal \/ 170 external<\/td><td>Bandwidth + delay by default<\/td><td>IP protocol 88<\/td><td>Cisco-centric enterprise<\/td><\/tr>\n<tr><td>OSPFv2 \/ OSPFv3<\/td><td>SPF (Dijkstra)<\/td><td>110<\/td><td>Interface cost<\/td><td>IP protocol 89<\/td><td>Multivendor enterprise<\/td><\/tr>\n<tr><td>EST-EST<\/td><td>SPF (Dijkstra)<\/td><td>115<\/td><td>Configured link metric<\/td><td>Directly over Layer 2<\/td><td>ISP cores, large-scale fabrics<\/td><\/tr>\n<tr><td>BGP (context only)<\/td><td>Path-vector decision process<\/td><td>20 eBGP \/ 200 iBGP<\/td><td>Policy attributes<\/td><td>TCP 179<\/td><td>Between autonomous systems<\/td><\/tr>\n<\/table><\/div>\n<p>Remember: administrative distance matters only when a router compares competing routes from different sources to the <strong>same prefix<\/strong>; it is not a routing-protocol performance score. EIGRP summarized-route AD 5 is platform\/context specific and is not the ordinary internal-route AD.<\/p><\/div>\n<div class=\"ig-sec\" id=\"section-2\"><div class=\"eyebrow\">Field guide \/ 02<\/div><h2>The shared four-router laboratory<\/h2><p class=\"description\">Use the same interfaces and addresses for independent protocol labs.<\/p><p>Interfaces on links (R1\u2013R2: R1 G0\/0 10.10.12.1\/30, R2 G0\/0 10.10.12.2\/30); (R2\u2013R3: R2 G0\/1 10.10.23.1\/30, R3 G0\/0 10.10.23.2\/30); (R1\u2013R3: R1 G0\/1 10.10.13.1\/30, R3 G0\/1 10.10.13.2\/30); (R3\u2013R4: R3 G0\/2 10.10.34.1\/30, R4 G0\/0 10.10.34.2\/30). R1 G0\/2 is 172.16.10.1\/24; R4 G0\/1 is 172.16.40.1\/24. Each router has a \/32 loopback matching its diagram label. Assign physical addresses before enabling a routing protocol. Use one protocol at a time in the lab; do not accidentally mix redistribution and overlapping route sources.<\/p><\/div>\n<div class=\"ig-sec\" id=\"section-3\"><div class=\"eyebrow\">Field guide \/ 03<\/div><h2>RIP: simplest concept, weakest scale<\/h2><p class=\"description\">Periodic vectors, hop limits, and loop avoidance.<\/p><p>Cisco IOS\/IOS XE sample on R1 (repeat the relevant classful <code data-no-translation=\"\">network<\/code> statements on other routers):<\/p>\n<pre data-no-translation=\"\"><code data-no-translation=\"\">router rip\n version 2\n no auto-summary\n network 10.0.0.0\n network 172.16.0.0\n passive-interface GigabitEthernet0\/2<\/code><\/pre>\n<p>Here <code data-no-translation=\"\">network 10.0.0.0<\/code> selects interfaces in the classful major network; <code data-no-translation=\"\">no auto-summary<\/code> preserves advertised subnet masks. Repeat <code data-no-translation=\"\">network 172.16.0.0<\/code> only on routers with a 172.16.x.x interface. By default RIPv2 sends updates every 30 seconds to 224.0.0.9. A hop count of 16 indicates unreachable. Prefer a modern IGP over RIP for production.<\/p><\/div>\n<div class=\"ig-sec\" id=\"section-4\"><div class=\"eyebrow\">Field guide \/ 04<\/div><h2>EIGRP: DUAL and loop-free backups<\/h2><p class=\"description\">Feasible successors are backup candidates, not just alternate neighbors.<\/p><p>Cisco classic-mode example on R3:<\/p>\n<pre data-no-translation=\"\"><code data-no-translation=\"\">router eigrp 100\n no auto-summary\n network 10.10.23.0 0.0.0.3\n network 10.10.13.0 0.0.0.3\n network 10.10.34.0 0.0.0.3\n passive-interface default\n no passive-interface GigabitEthernet0\/0\n no passive-interface GigabitEthernet0\/1\n no passive-interface GigabitEthernet0\/2<\/code><\/pre>\n<p>DUAL terms: Reported Distance (RD) is the neighbor&#x27;s advertised metric; Feasible Distance (FD) is the best metric from the local router to that prefix. A feasible successor must satisfy <strong>RD &lt; current successor FD<\/strong> (feasibility condition). A nonqualifying route could still be usable after recomputation, but is not a guaranteed loop-free backup. <code data-no-translation=\"\">show ip eigrp neighbors<\/code> verifies peers, <code data-no-translation=\"\">show ip eigrp topology<\/code> verifies the feasible successor and path state. Named EIGRP mode is recommended where supported; wide metrics and authentication syntax differ by platform.<\/p><\/div>\n<div class=\"ig-sec\" id=\"section-5\"><div class=\"eyebrow\">Field guide \/ 05<\/div><h2>OSPF: backbone, areas and DR\/BDR<\/h2><p class=\"description\">Multi-area IP routing built around a synchronized link-state database.<\/p><p>Example area plan: R1\u2013R2\u2013R3 links belong to area 0; R3\u2013R4 link and R4 LAN belong to area 10, making R3 an ABR. R1 LAN stays in area 0. R3 sample:<\/p>\n<pre data-no-translation=\"\"><code data-no-translation=\"\">router ospf 10\n router-id 3.3.3.3\n passive-interface default\n no passive-interface GigabitEthernet0\/0\n no passive-interface GigabitEthernet0\/1\n no passive-interface GigabitEthernet0\/2\n!\ninterface GigabitEthernet0\/0\n ip ospf 10 area 0\n ip ospf network point-to-point\ninterface GigabitEthernet0\/1\n ip ospf 10 area 0\n ip ospf network point-to-point\ninterface GigabitEthernet0\/2\n ip ospf 10 area 10\n ip ospf network point-to-point<\/code><\/pre>\n<p>Point-to-point OSPF links do not elect a DR\/BDR; shared broadcast Ethernet does. On a broadcast segment, DR and BDR election is non-preemptive and depends on priority, then router ID. OSPF states: Down \u2192 Init \u2192 2-Way \u2192 ExStart \u2192 Exchange \u2192 Loading \u2192 Full. Staying 2-Way can be normal between DROTHER neighbors. Check <code data-no-translation=\"\">show ip ospf neighbor<\/code>, <code data-no-translation=\"\">show ip ospf interface<\/code>, <code data-no-translation=\"\">show ip ospf database<\/code>, <code data-no-translation=\"\">show ip route ospf<\/code>. Match area, timers, authentication, network type, and subnet; monitor MTU problems in database exchange.<\/p><\/div>\n<div class=\"ig-sec\" id=\"section-6\"><div class=\"eyebrow\">Field guide \/ 06<\/div><h2>IS-IS: L1, L2 and NET addressing<\/h2><p class=\"description\">Link-state routing carried directly at Layer 2.<\/p><p>R1, R2 and R3 share area 49.0001; R4 sits in area 49.0002, so R3 is the area border. An IS-IS router has one area, set in its NET, for the whole process; areas are not assigned per interface. Because R3 and R4 are in different areas, the R3\u2013R4 link can form <strong>only a Level-2 adjacency<\/strong>, so both routers must run Level 2 (<code data-no-translation=\"\">is-type level-1-2<\/code>). Sample R3:<\/p>\n<pre data-no-translation=\"\"><code data-no-translation=\"\">router isis MAG212\n net 49.0001.0000.0000.0003.00\n is-type level-1-2\n metric-style wide\n!\ninterface GigabitEthernet0\/2\n ip router isis MAG212\n isis circuit-type level-2-only\n isis network point-to-point<\/code><\/pre>\n<p>R4 uses <code data-no-translation=\"\">net 49.0002.0000.0000.0004.00<\/code> et <code data-no-translation=\"\">is-type level-1-2<\/code> so its L2 connection to R3 operates across areas; R4&#x27;s LAN prefix sits in its Level-1 database and is advertised into Level 2 by default. IS-IS NET is not an interface IP address. Verify <code data-no-translation=\"\">show isis neighbors<\/code>, <code data-no-translation=\"\">show isis database<\/code>, <code data-no-translation=\"\">show isis topology<\/code>, <code data-no-translation=\"\">show clns interface<\/code>. Broadcast segments elect a DIS; point-to-point segments do not. IS-IS L2 is an inter-area routing level, not OSPF Area 0.<\/p><\/div>\n<div class=\"ig-sec\" id=\"section-7\"><div class=\"eyebrow\">Field guide \/ 07<\/div><h2>Routing protocol security<\/h2><p class=\"description\">Establish policy boundaries; assume the LAN could be hostile.<\/p><ol><li>Enable authentication supported by platform and routing mode (EIGRP HMAC-SHA-256 when available; OSPF authentication options depend on v2\/v3 and device; IS-IS authenticated PDUs); avoid publishing shared secrets in the article.<\/li><li>Set interfaces toward end-user LANs as passive when applicable; never form dynamic peers with untrusted clients.<\/li><li>Apply infrastructure ACLs and routing process filters for expected adjacencies and protocol traffic.<\/li><li>Filter inbound\/outbound prefixes at redistribution boundaries; avoid accidental default-route leaks and loops.<\/li><li>Limit management access with SSH, AAA, logging, NTP, and configuration backups; monitor adjacency churn.<\/li><li>Change reference-bandwidth consistently on all OSPF routers if higher link speeds warrant it.<\/li><li>Be cautious with <code data-no-translation=\"\">debug<\/code>, protocol clears, and authentication changes on live routers\u2014these may disrupt adjacencies.<\/li><\/ol><\/div>\n<div class=\"ig-sec\" id=\"section-8\"><div class=\"eyebrow\">Field guide \/ 08<\/div><h2>Troubleshooting decision tree<\/h2><p class=\"description\">Go from physical connectivity to peer state to route installation.<\/p><ul class=\"steps\"><li><strong>01 Physical:<\/strong> <code data-no-translation=\"\">show ip interface brief<\/code>, <code data-no-translation=\"\">show interfaces<\/code>, verify VLAN, speed, IP\/mask, ACL and bidirectional reachability.<\/li><li><strong>02 Protocol:<\/strong> <code data-no-translation=\"\">show ip protocols<\/code>; confirm interface enabled and correct process\/domain.<\/li><li><strong>03 Adjacency:<\/strong> RIP has no neighbor adjacency; inspect <code data-no-translation=\"\">show ip rip database<\/code> et <code data-no-translation=\"\">debug ip rip<\/code> carefully. EIGRP: <code data-no-translation=\"\">show ip eigrp neighbors<\/code>. OSPF: <code data-no-translation=\"\">show ip ospf neighbor<\/code>. IS-IS: <code data-no-translation=\"\">show isis neighbors<\/code>.<\/li><li><strong>04 Database:<\/strong> EIGRP <code data-no-translation=\"\">show ip eigrp topology<\/code>; OSPF <code data-no-translation=\"\">show ip ospf database<\/code>; IS-IS <code data-no-translation=\"\">show isis database<\/code>.<\/li><li><strong>05 RIB:<\/strong> <code data-no-translation=\"\">show ip route<\/code>, <code data-no-translation=\"\">show ip route &lt;prefix&gt;<\/code>; compare AD and route policy, check whether the next hop is reachable.<\/li><li><strong>06 Path:<\/strong> <code data-no-translation=\"\">traceroute &lt;destination&gt;<\/code> and check route summarization, redistribution, and return path.<\/li><li><strong>Common symptoms:<\/strong> OSPF EXSTART\/EXCHANGE: check MTU\/network type; EIGRP neighbors never form: verify AS, K-values, authentication and IP reachability; IS-IS missing L1: inspect NET area values; RIP remote prefixes missing: confirm correct <code data-no-translation=\"\">network<\/code> statements, <code data-no-translation=\"\">no auto-summary<\/code>, update filters and the 15-hop limit.<\/li><\/ul><\/div>\n<div class=\"ig-sec\" id=\"section-9\"><div class=\"eyebrow\">Field guide \/ 09<\/div><h2>Field exam: questions with explained answers<\/h2><p class=\"description\">Eight scenario questions, with the answer next to each question.<\/p><div class=\"qa\"><b>Q1. Which protocol runs over TCP\/179?<\/b><p>BGP. It is included for comparison but is not an IGP.<\/p><\/div><div class=\"qa\"><b>Q2. A RIP route reaches hop count 16. What happens?<\/b><p>It is considered unreachable.<\/p><\/div><div class=\"qa\"><b>Q3. What is EIGRP&#x27;s feasibility condition?<\/b><p>A backup neighbor&#x27;s reported distance must be strictly lower than the current successor&#x27;s feasible distance.<\/p><\/div><div class=\"qa\"><b>Q4. Why are two OSPF neighbors stuck in 2-Way?<\/b><p>Normal for two DROTHER routers on a broadcast segment; abnormal for a point-to-point adjacency that should become Full.<\/p><\/div><div class=\"qa\"><b>Q5. Why is an OSPF Type-2 LSA absent on a p2p Ethernet link?<\/b><p>No DR is elected in p2p mode, so there is no transit network LSA for that link.<\/p><\/div><div class=\"qa\"><b>Q6. Can IS-IS Level 1 routers in different areas become L1 neighbors?<\/b><p>No, their area IDs must match for L1.<\/p><\/div><div class=\"qa\"><b>Q7. Which protocol uses UDP\/520 and multicast 224.0.0.9?<\/b><p>RIPv2.<\/p><\/div><div class=\"qa\"><b>Q8. Two protocols advertise the same exact IPv4 prefix: EIGRP internal AD 90 and OSPF AD 110. Which is installed (assuming valid equal-prefix routes)?<\/b><p>EIGRP internal, because its AD is lower. Longest-prefix match still governs destination forwarding across <em>different<\/em> prefix lengths.<\/p><\/div><\/div>\n<div class=\"ig-sec\" id=\"section-10\"><div class=\"eyebrow\">Field guide \/ 10<\/div><h2>Legacy-reference corrections and modern notes<\/h2><p class=\"description\">Important distinctions when using older quick-reference sheets.<\/p><p>Older quick-reference sheets remain useful for terminology and command families, but some of their entries are era-specific: IPv6 protocol configuration differs across IOS\/IOS XE versions; classic EIGRP <code data-no-translation=\"\">no auto-summary<\/code> is relevant to older\/configuration modes; IS-IS is not an IP protocol number; OSPFv3 uses different LSA naming and addressing and should not be configured by blindly copying OSPFv2 commands. Older RIP and MD5 examples are primarily for legacy operation and lab familiarity. Always validate against your actual IOS XE version and feature set.<\/p><\/div>\n<div class=\"ig-sec\"><div class=\"eyebrow\">Field guide \/ 11<\/div><h2>Go deeper<\/h2><p>Each protocol has its own full MAG212 CYBER cheat sheet with a dedicated lab, diagrams and troubleshooting: <a href=\"\/fr\/learn\/rip-cheat-sheet\/\">D\u00c9CHIRER<\/a> \u00b7 <a href=\"\/fr\/learn\/eigrp-cheat-sheet\/\">EIGRP<\/a> \u00b7 <a href=\"\/fr\/learn\/ospf-cheat-sheet\/\">OSPF<\/a> \u00b7 <a href=\"\/fr\/learn\/isis-cheat-sheet\/\">EST-EST<\/a> \u00b7 <a href=\"\/fr\/learn\/bgp-cheat-sheet\/\">BGP<\/a>.<\/p><p>Sources: <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc2453\" target=\"_blank\" rel=\"noopener\">RFC 2453 (RIPv2)<\/a> \u00b7 <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc7868\" target=\"_blank\" rel=\"noopener\">RFC 7868 (EIGRP)<\/a> \u00b7 <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc2328\" target=\"_blank\" rel=\"noopener\">RFC 2328 (OSPFv2)<\/a> \u00b7 <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc1195\" target=\"_blank\" rel=\"noopener\">RFC 1195 (Integrated IS-IS)<\/a> \u00b7 <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc4271\" target=\"_blank\" rel=\"noopener\">RFC 4271 (BGP-4)<\/a><\/p><\/div>\n<\/div><div class=\"ig-foot\">\u00a9 2026 MAG212 CYBER \u00b7 Learn \/ Cheat Sheets \u00b7 Educational lab, validate syntax for your IOS XE platform.<br><a href=\"\/fr\/learn\/\">Plus de guides dans Apprendre<\/a> \u00b7 <a href=\"\/fr\/services\/\">Conseil en r\u00e9seau et s\u00e9minaires<\/a><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>RIP, EIGRP, OSPF and IS-IS compared: one four-router lab, IOS XE configs, troubleshooting decision tree and exam questions.<\/p>","protected":false},"author":1,"featured_media":0,"parent":3385,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3428","page","type-page","status-publish","hentry"],"_hostinger_reach_plugin_has_subscription_block":false,"_hostinger_reach_plugin_is_elementor":false,"_links":{"self":[{"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/pages\/3428","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/comments?post=3428"}],"version-history":[{"count":0,"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/pages\/3428\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/pages\/3385"}],"wp:attachment":[{"href":"https:\/\/cyber.mag212.com\/fr\/wp-json\/wp\/v2\/media?parent=3428"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}