, bạn có thể sử dụng lệnh tóm tắt địa chỉ để hạn chế các tuyến đường từ tuyên truyền L1 và L2. Đối với L1, lệnh router địa chỉ tóm tắt được sử dụng để tóm tắt các tuyến đường bên ngoài chỉ. Đối với L2, lệnh summaryaddress được sử dụng để tổng kết các tuyến đường bên ngoài cũng như các tuyến đường L1. | Another reason for migrating classful protocols such as RIP or IGRP involves support for VLSM. As the network grows administrators begin to realize that wasting address space merely to accommodate the protocol becomes a serious issue. RIP and IGRP do not support VLSM so all the interfaces included in the same major network should have the same mask. When connecting a large number of hosts in broadcast media for a class B network you would mask with 24. For point-to-point connections you might use a 30-bit mask to use the same subnet for 64 point-to-point connections. Another reason for migrating to another protocol is faster convergence. Again the older classful protocols are periodic which means that you must put the route in holddown and flush states. In the worst case this could take minutes to converge. Because of the rapid pace of the Internet this sluggish convergence is unacceptable. Classful protocols also lack the capability to summarize within the network. The administrator for example might want to summarize some routes within a region to diminish the size of the routing table. NOTE Essentially migration of routing protocols is carried out to improve classfulness and to provide support for VLSM support for discontiguous networks scaling and faster convergence. The third situation relates to the scaling protocols but more in terms of the ISP space rather than the enterprise space. ISPs often mistakenly advertise customer routes into the IGP because ISPs usually undergo tremendous growth. When the ISP begins redistribution its customer base is modest in size. However the customer routes increase as the business expands. Before long an ISP could have 5 000 to 6 000 customer routes floating in its IGP so if a problem occurs on the customer networks it can wreak havoc on the ISP networks. These issues are discussed in detail in the next section. Migration of Routing Protocols Routing-protocol migration can be divided into three categories Migrating from a .
