trong việc cấu hình và xử lý sự cố các giao diện mạng của hệ thống. Sau khi hoàn thành mô-đun này, bạn sẽ có thể Mô tả Ethernet khái niệm Mô tả khung Ethernet Sử dụng tiện ích mạng Bản đồ khóa học sau đây cho thấy làm thế nào mô-đun này phù hợp với mục tiêu giảng dạy hiện nay. | Introducing Subnetting and VLSM The etc inet netmasks File A network mask netmask is defined for each of the three classes of IPv4 addresses so that the system can compute the network number from any given IPv4 address. The etc inet netmasks file is linked to the etc netmasks file. The file enables the permanent assignment of a netmask. When the system reboots this file is consulted before the configuration of the network interfaces. The etc rcSd script consults the etc inet netmasks file at run level S. At run level 2 the etc S72inetsvc script can recalculate the netmask using the Network Information Service NIS maps or Network Information Service Plus NIS databases. For every network that is subnetted an individual line is entered into this file. The fields in the etc inet netmasks file list the network number and the netmask definition. An example of an entry for a subnetted Class B network is An example of an entry for a subnetted Class C network is If a netmask is not specified in the etc inet netmasks file for the system to use during system startup a default Class A B or C netmask is assumed. You can also configure an interface s netmask from the command line by using the ifconfig utility. sys11 ifconfig qfe0 netmask 0xffffff00 up or sys11 ifconfig qfe0 netmask up Contiguous Netmasks RFC 950 recommends the use of contiguous subnet masks. A contiguous subnet mask is one that only uses contiguous high-order bits. For example 11111111 11111111 11111111 11110000 Configuring IP Copyright 2002 Sun Microsystems Inc. All Rights Reserved. Enterprise Services Revision A 5-11 Introducing Subnetting and VLSM Noncontiguous Netmasks Although RFC 950 recommends only the use of contiguous subnet masks nothing prevents the use of noncontiguous subnet masks. For example 11111111 11111111 11111111 01001010 However using noncontiguous subnet masks makes administration
