OSPF ABR LSA Type 3 Filtering

ABRs do not forward type 1 and 2 LSAs from one area into another, but instead create type 3 LSAs for each subnet defined in the type 1 and 2 LSAs. Type 3 LSAs do not contain detailed information about the topology of the originating area; instead, each type 3 LSA represents a subnet, and a cost from the ABR to that subnet. The earlier section “LSA Type 3 and Inter-Area Costs” covers the details and provides an example. The OSPF ABR type 3 LSA filtering feature allows an A..

Layer 3 Security

The Cisco SAFE Blueprint also lists several best practices for Layer 3 security. The following list summarizes the key Layer 3 security recommendations from the SAFE Blueprint. 1. Enable secure Telnet access to a router user interface, and consider using Secure Shell (SSH) instead of Telnet. 2. Enable SNMP security, particularly adding SNMPv3 support. 3. Turn off all unnecessary services on the router platform. 4. Turn on logging to provide an audit trail. 5. Enable routing ..

Basic BGP Configuration—EBGP

External BGP (EBGP) neighbors are usually directly connected. In Figure 8-13, you configure EBGP between Routers A and B and investigate the operation and configuration of EBGP neighbors. Figure 8-13. Configuring EBGP The first step in configuring EBGP is to configure a loopback interface on Routers A and B. (See Example 8-2.) As with OSPF, the IP address assigned to the loopback interface is used as the BGP router ID. Example 8-2. Configuring Loopback Interfaces on Routers..

Using RSVP

Basic RSVP configuration is relatively simple. All you need to do is define how much bandwidth can be reserved on the interface: Router#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Router(config)#interface FastEthernet0/0 Router(config-if)#ip rsvp bandwidth 128 56 Router(config-if)#exit Router(config)#end Router# Some network administrators have to worry about unauthorized use of bandwidth reservation. You can control this by specify..

Dealing with Passive Mode FTP

This example shows how to filter a Passive FTP control and data sessions: Router1#configure terminal Enter configuration commands, one per line.  End with CNTL/Z.Router1(config)#access-list 144 permit tcp any gt 1023 any eq ftpRouter1(config)#access-list 144 permit tcp any gt 1023 any gt 1023Router1(config)#access-list 144 deny ip any any                   Router1(config)#interface..