1.PVST
PVST is a specific solution of Cisco to process spanning trees on virtual LANs. PVST runs separate spanning tree instances for each virtual LAN. Generally, PVST requires Cisco ISLs to be run on the trunk links between switches. Per VLAN Spanning Tree (PVST) maintains one spanning tree instance for each VLAN configured in the network. It uses ISL trunk and allows a VLAN trunk to forward some VLANs when blocked by other VLANs. Although PVST treats each VLAN as a separate network, it has the ability (at layer 2) to load balance communication through some VLANs in the backbone and other VLANs in another backbone that do not cause spanning tree loops.
2.HSRP
The design goal of the Hot Standby Routing Protocol (HSRP) is to support the failure transfer of IP traffic under certain circumstances without causing confusion, allow the host to use a single router, and maintain the connectivity between routers even if the first hop router fails to work. In other words, when the source host cannot dynamically know the IP address of the first hop router, the HSRP protocol can protect the first hop router from failure. The protocol contains multiple routers, corresponding to a virtual router. HSRP protocol only supports one router to implement the packet forwarding process on behalf of the virtual router. The end hosts forward their respective packets to the virtual router.
3.VRRP (Virtual Router Redundancy Protocol)
VRRP is a selective protocol, which can dynamically assign the responsibility of a virtual router to one of the VRRP routers on the LAN. The VRRP router that controls the IP address of the virtual router is called the active router. It is responsible for forwarding packets to these virtual IP addresses. Once the active router is unavailable, this selection process provides a dynamic failover mechanism, which allows the IP address of the virtual router to be used as the default first hop router of the terminal host. The advantage of using VRRP is that it has higher availability of default paths without configuring dynamic routing or route discovery protocols on each end host. VRRP packets are encapsulated and sent in IP packets. With VRRP, you can manually or DHCP set a virtual IP address as the default router. Virtual IP addresses are shared among routers, one of which is designated as the active router and the other as the standby router. If the active router is unavailable, the virtual IP address is mapped to the IP address of a standby router and the standby router becomes the active router.
VRRP can also be used for load balancing. VRRP is part of IPv4 and IPv6. VRRP (Virtual Router Redundancy Protocol) is a fault-tolerant protocol. Generally, all hosts in a network set a default route, so that the messages sent by the host with a destination address not in the network segment will be sent to Router A through the default route, thus realizing the communication between the host and the external network. When Router A fails, all hosts in this network segment that take Router A as the default route for the next hop will lose communication with the outside. VRRP is proposed to solve the above problems. It is designed for local area networks (such as Ethernet) with multicast or broadcast capabilities
4.MPLS
Multi-Protocol Label Switching (MPLS) is a system for fast packet switching and routing. It helps network data traffic to realize arriving, routing, forwarding and switching. More specifically, it has a mechanism to manage various forms of communication flow. MPLS is independent of layer 2 and layer 3 protocols, such as ATM and IP. It provides a way to map IP addresses into simple tags with fixed length for different packet forwarding and packet switching technologies. It is the interface of existing routing and switching protocols, such as IP, ATM, Frame Relay, Resource ReSerVation Protocol (RSVP), Open Shortest Path First (OSPF), etc. MPLS is mainly designed to solve network problems, such as network speed, scalability, Quality of Service (QoS) management and traffic engineering. It also solves the problems of broadband management and service requests for the next generation IP backbone network.
QoS (Quality of Service)
QoS is a security mechanism of the network. It is a technology used to solve the problems of network delay and blocking. Under normal circumstances, if the network is only used for specific application systems such as web applications or e-mail settings without time limit, QoS is not required. But it is very necessary for key applications and multimedia applications. When the network is overloaded or congested, QoS can ensure that important traffic is not delayed or discarded, and ensure the efficient operation of the network.
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