CISCO Protocol Summary (1)

The network protocols used by Cisco are classified and described in terms of network, route, data link, and network security technology.

1. Cisco Network Routing Protocol Network/Routing)

CGMP: Cisco Group Management Protocol)

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IGRP: Internal Gateway Routing Protocol IGRP: Interior Gateway Routing Protocol)

HSRP: Hot Backup Router Protocol HSRP: Hot Standby Routing Protocol)

RGMP: Cisco Router Port Group Management Protocol

CGMP: Cisco Group Management Agreement

CGMP: Cisco Group Management Protocol

The Cisco Group Management Protocol CGMP is used to limit forwarding of IP multicast packets only to ports connected to IP multicast clients. These clients are automatically added to and removed from the group that receives IP multicast traffic. The switch dynamically changes the forwarding behavior based on the request. CGMP mainly provides the following services:

Allow IP multicast packets to be switched to the ports with IP multicast clients.

The network bandwidth is stored in the user field, which does not result in unnecessary IP multicast traffic for broadcasting.

You do not need to change the terminal host system.

No additional overhead is incurred when creating an independent VLAN for each multicast group in the switched network.

Once CGMP is activated for use, it can automatically identify the port connecting to the CGMP-Capable router. CGMP is activated by default. It supports IP multicast group registration up to 64. A Multicast router that supports CGMP periodically sends the Join message to Join Messages. This is used to notify itself to perform network switching. The receiving switch saves information and sets a Timer similar to the vro holding time (Holdtime ). Each time a switch receives a CGMP entry, the timer is updated with it. When the maintenance time of the vro is terminated, the vswitch is responsible for removing all known multicast groups from CGMP.

CGMP works with IGMP information to dynamically allocate Cisco Catalyst Switch ports, so that IP multicast traffic is forwarded only to the ports connected to the IP multicast client. Since the CGMP-Capable IP multicast router sees all IGMP packets, it can notify the vswitch when to join or leave the IP multicast group. When the CGMP-Capable router receives an IGMP control data packet, it creates a CGMP data packet including the request type joining or leaving), multicast group address and valid MAC address of the host. The router then sends the CGMP packet to the address known to all Catalyst switches. When a switch receives CGMP data packets, the switch is responsible for converting the data packets and reorganizing the forwarding behavior of the multicast group. At this point, the multicast traffic is only sent to the ports connected to the multicast client with the appropriate IP address. This process is automatically implemented without user involvement.

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VPN: Enhanced Interior Gateway Routing Protocol

The enhanced internal gateway routing protocol (IPSec) is an enhanced version of the IGRP protocol. IGRP is an internal gateway routing protocol provided by Cisco for TCP/IP and OSI Internet services. It is regarded as an internal gateway protocol, and as an external gateway protocol for intra-domain routing selection, it has not been widely used yet.

The main differences between Enhanced IGRP and other route selection protocols include: Convergence wide speed Fast Convergence), support for variable-length Subnet Mask), local update, and multi-network layer protocol. The router that executes the Enhanced IGRP stores all its adjacent Route tables so that it can quickly take advantage of the various alternative paths Alternate Routes ). If there is no proper path, Enhanced IGRP queries its neighbor to obtain the required path. The Enhanced IGRP query is terminated until a proper path is found. Otherwise, the query continues.

The network type of any subnet mask is used to aggregate all the route entries in the network. This reduces the transmission of route information and saves bandwidth. In addition, you can configure the VPN protocol to support route aggregation on the bitwise border router of any interface.

Enhanced IGRP does not perform periodic updates. When the path measurement standard changes, Enhanced IGRP only sends Partial update Partial Updates) information. The transmission of partial update information is automatically limited, so that only the routers that need the information are updated. Based on the above two types of performance, Enhanced IGRP consumes much less bandwidth than IGRP.

IGRP: Internal Gateway Routing Protocol

IGRP: Interior Gateway Routing Protocol

The Internal Gateway Routing Protocol (IGRP) is a routing protocol that provides the routing selection function in the autonomous system AS: autonomous system. In the 1980s s, the most common internal routing protocol (RIP) was the routing information protocol ). Although RIP is very useful in the selection of routes for small or medium-sized interconnected networks, with the continuous development of the network, its restrictions become more and more obvious. The practicality of Cisco routers and the powerful functionality of IGRP allow many small interconnected network organizations to replace RIP with IGRP. As early as the 1990s S, CISCO launched an enhanced IGRP, which further improved the operation efficiency of IGRP.

IGRP is a Distance Vector (Distance Vector) Internal Gateway Protocol (IGP ). The distance vector routing selection protocol uses the mathematical distance standard to calculate the path size. This standard is the distance vector. The distance vector Routing selection protocol is usually opposite to the Link-State Routing Protocols Protocol. This is mainly because the distance vector Routing protocol sends local connection information to all nodes on the Internet.

For greater flexibility, IGRP supports the multi-path routing selection service. In the Round Robin (Round Robin) mode, two equal-bandwidth lines can run a single communication stream. If the transmission of one line fails, the system automatically switches to the other line. Multi-path can be a multi-path line with different standards but still works. For example, if one line is three times lower than the other, that is, three levels lower than the standard), it means that this path can be used three times. Only a path that meets a specific Optimal Path range or within the difference range can be used as a multi-path. Variance) is another value that the network administrator can set.

HSRP: Hot Backup Router Protocol

HSRP: Hot Standby Router Protocol

Hot Backup Router Protocol (HSRP) is designed to support the failure of IP traffic transfer under certain circumstances, which will not cause confusion and allow the host to use a single router, and maintain the connectivity between routers even if the first hop router fails to be used. 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 vrouters corresponding to one vro. The HSRP protocol supports only one vro to forward data packets. The terminal host forwards their respective packets to the vro.

The Router responsible for packet forwarding is called the Active Router ). Once the active router fails, HSRP will activate the backup router Standby Routers) to replace the active router. The HSRP Protocol provides a mechanism to determine whether to use an active router or back up a router, and designate a virtual IP address as the default gateway address of the network system. If the active router fails, back up the router Standby Routers to undertake all the tasks of the active router, and the host connection will not be interrupted.
HSRP runs on UDP and port 1985 is used. The source address of the router packet forwarding protocol uses the actual IP address instead of the virtual address. Based on this, HSRP routers can recognize each other.
RGMP: Cisco router port group management protocol

RGMP: Cisco Router Port Group Management Protocol

Cisco router port Group Management Protocol (RGMP) makes up for the shortcomings of the Internet Group Management Protocol (IGMP: Internet Group Management Protocol) in the Snooping technical mechanism. The RGMP protocol acts between multicast routers and switches. RGMP allows you to fix multicast data packets forwarded by vswitches in the required vro. RGMP is designed to be used in Backbone Switched Networks, a Backbone exchange network connected to multiple routers ).

The limitations of the IGMP Snooping technology are mainly reflected in the following: this technology can only fix multicast traffic to an exchange port that is directly or indirectly connected to the receiver through other switches. In the IGMP Snooping technology, multicast traffic cannot be fixed at least on the port connected to a multicast router, resulting in the spread of multicast traffic on these ports. IGMP Snooping is an inherent limitation of the mechanism. Based on this, the vro cannot report the traffic status. Therefore, the vswitch only knows the multicast traffic type requested by the host, but does not know the traffic type received by the vro port.

The RGMP protocol allows you to set multicast traffic to vro ports. To efficiently implement traffic fixation, both network switches and routers must support RGMP. Through RGMP, the backbone switch can know the group type required by each port, and then the multicast router sends the information to the switch. However, the router only sends RGMP information, while ignoring the received RGMP information. When the Group no longer needs to receive communication traffic, the router will send an RGMP departure Message Leave Message ). In the RGMP protocol, network switches need to consume network ports to achieve RGMP information and perform operations on them. In addition, switches in RGMP cannot forward/spread the received RGMP information to other network ports.

RGMP is designed to be used in combination with the multicast routing selection protocol that supports the distribution tree Join/Prune. The typical protocol is PIM-SM. The RGMP protocol only specifies the IP v4 Multicast Route Selection operation, excluding IP v6.

2. Cisco Data Link Protocol Data Link)

CDP: Cisco Discovery Protocol)

DTP: Cisco Dynamic relay Protocol DTP: Dynamic Trunk Protocol)

ISL & DISL: Cisco Switch Link Protocol and dynamic ISL Protocol ISL: Inter-Switch Link Protocol)

VTP: Cisco VLAN relay Protocol VTP: VLAN Trunking Protocol)

CDP: Cisco Discovery Protocol CDP

CDP: Cisco Discovery Protocol

CDP is basically used to obtain the Protocol addresses of adjacent devices and platforms for discovering these devices. CDP can also provide related interface information for vro use. CDP is an independent media protocol that runs on all devices manufactured by Cisco, including routers, bridges, access servers, and switches.

In SNMP, the basic MIB of CDP management information can be used together to notify the network management application of the device type and the SNMP proxy address of adjacent devices, and send SNMP query requests to these devices. The Cisco Discovery protocol supports CISCO-CDP-MIB.

CDP runs on all media to support the subnet access protocol SNAP, including LAN, frame relay, and asynchronous transmission mode ATM physical media. CDP only runs on the data link layer. Therefore, two systems that support different network layer protocols understand each other.