Operation Manual – Routing ProtocolH3C S7500 Series Ethernet Switches Chapter 1 IP Routing Protocol Overview1-4route. Routing protocols and their default route preferences (the smaller the value is,the higher the preference is) are shown in Table 1-1.In the table, “0” is used for directly connected routes, and “255” is used for routes fromuntrusted source.Table 1-1 Routing protocols and corresponding route preferencesRouting protocol or type Preference of the corresponding routeDIRECT 0OSPF 10IS-IS 15STATIC 60RIP 100OSPF ASE 150OSPF NSSA 150UNKNOWN 255IBGP 256EBGP 256Except for direct routing, you can manually configure the preferences of variousdynamic routing protocols as required. In addition, you can configure differentpreferences for different static routes.1.2.2 Traffic Sharing and Route BackupI. Traffic sharingThe S7500 series support multi-route mode, allowing the configuration of multipleroutes that reach the same destination and have the same preference. The samedestination can be reached via multiple different routes, whose preferences are equal.When there is no route with a higher preference to the same destination, all theseroutes will be adopted. Then, the packets destined for that same destination will beforwarded through these routes in turn to implement traffic sharing.II. Route backupThe S7500 series support route backup. When the primary route fails, the systemautomatically switches to a backup route to improve network reliability.To achieve route backup, you can configure multiple routes to the same destinationaccording to actual situation. One of these routes has the highest preference and iscalled primary route. The other routes have descending preferences and are called
