34Slot Arrangement and Rules for Numbering InterfacesSlot arrangementThe MSR 20-1X routers provide many types of interfaces, such as console, AUX, Ethernet, serial interface(synchronous/asynchronous), and asynchronous interface. The following describes how these interfacesare numbered.Rules for numbering interfacesThe interfaces of the MSR 20-1X routers are numbered with “two dimensions”:• The interfaces are represented by interface-type X/Y, where interface-type can be serial,asynchronous, or Ethernet, X specifies the slot number and Y specifies the interface number.• Fixed interfaces are on Slot 0 and the expansion slot is defined as Slot 1.• Different interfaces on an interface module share the same slot number X.• For each interface, Y starts from 0 indicates the interface sequence on the interface module, fromleft to right.If you install an SIC-4FSW in slot 1 on the MSR 20-11, the Ethernet interfaces are numbered as follows:• Layer 3 Ethernet interface is numbered Ethernet 0/0;• The Layer 3 Ethernet interfaces on the SIC-4FSW module are numbered Ethernet 1/0, Ethernet 1/1,Ethernet 1/2, and Ethernet 1/3.
