Determining the Designated Router Using the priority Command
Remember that hello messages include a priority field and thus provide a mechanism by which the DR and BDR are elected. To be "up for election," the priority must be a positive integer between 1 and 255. If its priority is 0, the router cannot participate in the election. Otherwise, highest priority wins. All Cisco routers have a default priority of 1, and the highest router ID is used as a tiebreaker. As previously discussed in the "Electing DRs and BDRs" section, the comman..
Terminal Access Controller Access Control System Plus
Cisco IOS supports three versions of TACACSTACACS, extended TACACS, and TACACS+. All three methods authenticate users and deny access to users who do not have a valid username/password pairing. TACACS+ is Cisco proprietary, whereas RADIUS is an open standard originally created by Livingston Enterprises. Cisco has also developed Cisco Secure Access Control Server (ACS), a flexible family of security servers that supports both RADIUS and TACACS+. You can even run debugging com..
SDLC is a serial protocol that is commonly used for SNA devices. It is extremely popular in financial environments for devices such as banking machines, card readers, and account printers. Using SDLC in conjunction with DLSw is becoming increasingly common in these sorts of situations. This allows the remote SDLC devices to communicate with the Token Ring Interface Coupler (TIC) on a mainframe computer through an IP network. There is a huge advantage to this because it means ..
Configuring WRED for Frame Relay
This section demonstrates the configuration tasks required to enable WRED for Frame Relay. WRED can be configured at the interface level or within the policy-map to initiate the WRED drop mechanism on a per-class basis for CBWFQ or LLQ. Enabling WRED on an Interface To enable WRED on an interface, use the following commands, beginning in the global configuration mode: Step 1. Enter the interface configuration mode of the Frame Relay interface on which yo..
Before moving on to discuss how to influence route choices by changing the OSPF interface costs, first take a moment to consider the CPU-intensive SPF work done by a router. SPF does the work to piece together topology information to find all possible routes to a destination. As a result, SPF must execute when the intra-area topology changes, because changes in topology impact the choice of best route. However, changes to Type 3 LSAs do not drive a recalculation of the ..
