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HSRP BFD Peering Posted in: IP Services - HSRP BFD Peering combines Hot Standby Router Protocol (HSRP) with Bidirectional Forwarding Detection (BFD) to reduce gateway failover time. By default, HSRP detects a peer failure only after the hold timer expires, which can take up to 10 seconds by default. BFD allows sub-second detection and notifies HSRP immediately when the router on the other… ... Continue Reading
HSRP Preemption Posted in: IP Services - Hot Standby Router Protocol (HSRP) preemption allows a higher-priority router to take back the active role when it returns to the network. Without preemption, whichever router becomes active first stays active. Even if a higher-priority router comes back online later. In this lesson, we demonstrate exactly that difference. First, we run through the scenario without… ... Continue Reading
IPv6 Device Tracking Posted in: CCIE Enterprise Infrastructure, IPv6 - IPv6 ND has no built-in authentication. Any device can send Neighbor Advertisements (NA) claiming any IPv6 address. Luckily, there is something we can do about this. IPv6 Device Tracking is part of the IPv6 First Hop Security feature set and the modern name for what used to be configured with the legacy IPv6 first-hop security… ... Continue Reading
HSRP for IPv6 Posted in: CCIE Enterprise Infrastructure, CCNP ENCOR 350-401, IP Services, IPv6 - Hot Standby Router Protocol (HSRP) for IPv6 is a Cisco proprietary First Hop Redundancy Protocol (FHRP) that lets two or more routers share a single virtual IP address, giving hosts a highly available default gateway. If the active router fails, the standby router takes over automatically. You don't have to reconfigure the default gateway on… ... Continue Reading
HSRP State Machine Explained Posted in: IP Services - Hot Standby Router Protocol (HSRP) uses a state machine to figure out which router becomes active and forwards traffic for a virtual IP address. The other router(s) become standby routers in case the active one fails. The state machine has six operational states, the events that trigger transitions between them, and the actions executed during… ... Continue Reading