Cisco

Several commands can be utilised to check on the status of HSRP on a router. show standby can display HSRP status across the router. Its output can be limited by adding the suffix interface <interface> along with a summarised output with the additional keyword brief

Begin in interface configuration mode, the HSRP instance can be configured with the command standby <group-number> ip <virtual-ip-address> If preemption is to be enabled, the command standby <group-number> preempt must be entered. This means if a router with a higher priority joins the group than the current active router, it will assign the active role…

A Cisco proprietary protocol, Hot Standby Router Protocol (HSRP), provides transparent failover of a gateway device in a network. A minimum of two devices are required to enable Hot Standby Router Protocol. One of the devices acts as the active gateway in the network whilst the other remains in a standby position ready to take…

Object tracking can check on specific objects in the network, and work with First Hop Redundancy Protocols to take various actions depending on that objects status. For example, the reachability of route of 192.168.1.0/24 can be tracked with the following command in global configuration mode: track 10 ip route 192.168.1.0/24 reachability The status of that…

In an NTP architecture, the NTP client changes the time to reflect that of the chosen NTP server. The NTP server will not change its time to match that of a clients. NTP peers can act as clients and servers to each other – they blend their time to each other. An NTP peer will…

If an NTP client is configured with multiple NTP servers, the device will only use the NTP server with the lowest stratum.

Client Configuration To configure a client to utilise NTP, in global configuration mode use the following command: ntp server x.x.x.x Replace x.x.x.x with the IP address of the NTP server. There are additional keywords prefer and source. Prefer will set the server as a preferred NTP source. Source is to set the source interface where…

RFC 958 introduced network time protocol. Network time protocol can be utilised to synchronise a set of clocks on network devices on a client to server model. Synchronising time is important on network devices. Time is used for many different features on network devices such as managing time specific passwords, key exchanges, checking the validity…

Congestion avoidance monitors network traffic loads to anticipate and avoid congestion by dropping packets. The default method of dropping packets is tail drop. When the output queue is full, all packets trying to enter the queue are dropped regardless of their priority or classification. Tail drop can be drastic for TCP streams, and can cause…