Comprehensive introduction to the protocol for selecting routes from the drop-down list

It is very helpful to know some knowledge about the route selection protocol. So I have studied the basic knowledge of VPN in the routing protocol and will share it with you here. I hope it will be useful to you. VPN is a Cisco dedicated protocol that combines the advantages of link status and distance vector routing selection protocol. The source protocol is the distance vector routing protocol. Easy to configure and suitable for various network topologies. It adds several link state features, such as dynamic Neighbor Discovery, which makes it an advanced distance vector routing selection protocol.

Compared with the traditional distance vector routing protocol, VPN Gateway provides more benefits. One of the most important benefits is bandwidth usage. When the network protocol is used, the route selection protocol runs data streams mainly through multi-object multicast instead of broadcasting. The result is that non-end sites are not affected by route updates or query information. The algorithm in IGRP is used to calculate the measurement value. However, this value is expressed in a 32-bit format. The measurement value of ixel is to multiply the measurement value of IGRP by 256. An important advantage of network replication is that it supports load balancing of non-equal metric values, allowing administrators to better distribute data streams in the network. IP packets containing information about e iprp use Protocol Number 88 in their headers.

It is designed to run in the LAN and WAN environments at the same time. The neighbor relationship is formed and maintained through a reliable multi-object multicast mode. It also supports a systematic IP address addressing. E igrp also supports VSM, which promotes the effective allocation of IP addresses. By default, the routing selection protocol is summarized in the primary network boundary, and VPN supports supernet) create or aggregate address blocks.

Concept

Neighbor table-each VPN Router maintains a route table with adjacent routers. This table is adjacent to the neighbor relationship used by OSPF.) The database is comparable.
Topology table-the topology table is maintained for all the first network protocols configured by the routers.
Route table --- select the optimal route from the topology table to the destination and place the routes in the route table.
Successor) --- this is the main router used to reach the destination.
Feasible Successor router Feasibe Successor, FS) --- a backup route to the destination.

Using the following five types of data packets:

HEO---HEO data packets land to discover neighbors.
Update-the update information is sent to notify the route that has been considered to be converged by a vro.
Query-when the Router performs route selection protocol calculation but fails to find a feasible route selection protocol, it sends a query packet to its neighbor to ask whether they have a feasible route to the destination.
Reply --- the reply packet is used to respond to the query data packet.
Confirm ACK) --- confirmation is used to confirm updates, queries, and replies.

Reliability

The Reliability Technology of VPN ensures the transmission of key route information of the router that expires. This information is required for the maintenance of the non-loop topology of the network. Data of all route selection protocol information updates, queries, and replies are reliably sent. The Reliable Transport Protocol (RTP) is responsible for the guaranteed and ordered transmission of VPN packets to all neighbors. It supports hybrid transmission of multicast or single-point transmission data packets. For efficiency, only some e igrp packets are reliably transmitted. RTP ensures that ongoing communication between adjacent routers can be maintained. Therefore, it maintains a retransmission table for the first neighbor. This table indicates data packets that have not been confirmed by neighbors. Unconfirmed reliable data packets can be retransmitted for a maximum of 1 6 times or until the retention time times out, which is limited to the longer of them. After the HEO protocol is used, the VPN Router can dynamically discover other routers that are directly connected to it.

How to use the link bandwidth of Network-side replication Gateway

By default, the VPN gateway uses up to 50% of the bandwidth announced on the API or subinterface. You can use the following interface command to adjust the percentage:
Router (config-if) # ip bandwidth-percent VPN as-number percent

Verify the commands run by using the command

Show ip VPN nodes Show the nodes that are located in the network.
Show ip VPN topology
Show ip route: displays the current OSPF entries in the route selection protocol.
Show ip protocos displays the parameters and current status of active route selection Protocol process
Show ip OSPF traffic: displays the number of sent and received OSPF packets.

DEBUG Command

Display the type of the received and sent network-connected devices.
Debug OSPF neighbors: displays the neighbor and HEO packet content detected by OSPF.
Debug ip: displays the OSPF Packet sent and received on the API.
Run the Debug ip "VPN summary" command to display the summary information of the VPN gateway.