TACACS+ Communications Architecture
TACACS+ communications occur using TCP as the transport mechanism. TACACS+ uses port number 49 to communicate. TACACS+ uses the concept of a session to define the set of exchanges taking place to perform either authentication, authorization, or accounting. Typically, each session has a separate TCP connection, but multiple sessions can be multiplexed onto the same TCP connection. In general, TCP offers quite a few advantages to TACACS+ in terms of a rugged communications arc..
Understanding Level 1 and Level 2 Routing
In level 1, IS nodes are based on the ID portion of the address. All level 1 routers route within their own area. They recognize the destination within their area by reading the destination address. If the destination is within the same area, the packet is routed to the destination. If the destination is not within the same area, it is sent to the closest level 2 router. In IS-IS, all level 1 areas are stub areas, so no information is sent to level 1 routers tha..
IGMPv1 Host Membership Report Functions
Hosts use IGMPv1 Host Membership Report message to reply to IGMP Queries and inform the router(s) of their desire to receive multicasts. Multicast hosts use IGMPv1 Host Membership Report messages to communicate to a local router for which multicast groups they want to receive traffic. In IGMPv1, a host sends an IGMPv1 Host Membership Report under the following two conditions: ■ When a host receives an IGMPv1 Query from a local router, it is supposed to send an IGMPv1 Hos..
QoS Requirements of the Control Plane
Unless the network is up, QoS is irrelevant. Therefore, it is critical to provision QoS for control-plane traffic, which includes IP routing traffic and network management. IP Routing When addressing the QoS needs of IP routing traffic, the following guidelines are recommended: • IP routing traffic should be marked to DSCP CS6; this is default behavior on Cisco IOS platforms. • Interior gateway protocols usually adequately are protec..
Because VRRP and GLBP perform a similar function to HSRP, you can use a similar troubleshooting philosophy. Much like HSRP’s show standby brief command, similar information can be gleaned for VRRP operation with the show vrrp brief command and for GLBP operation with the show glbp brief command. Although HSRP, VRRP, and GLBP have commonalities, it is important for you as a troubleshooter to understand the differences. Table 5-4 compares several characteristics of these fir..
