Differences between Cisco switch stack and HSRP

With the increasing popularity of the Internet, people are increasingly dependent on the network. At the same time, this puts forward higher requirements on Network stability. People naturally think of a device-based backup structure, just like using a dual hard disk structure on servers to improve data security. The core switch is the core and heart of the entire network. If a fatal fault occurs on the core switch, it will paralyze the local network and cause incalculable losses.
Currently, all layer-3 switches in the industry adopt the hot backup routing protocol (VRRP), while Cisco generally uses its own proprietary hot backup routing protocol (HSRP ), however, Cisco Catalyst 3750 series switches are generally stacked to form a logical switch by stacking multiple switches together with their own stacking lines. Next let's take a look at the stack and HSRP (hot backup routing protocol) Introduction. At present, more and more Cisco products support stacking at www.2cto.com. Currently, Cisco Catalyst 3750 series are supported, while 2960S, 3560X, and 3750X support both, however, for these new models, a dedicated stack module is required to use the stack function, and the Cisco Catalyst 3750 series provides a 0.5 stacked wire by default in the box, 3750 switches are connected to each other through Cisco proprietary stack cables. up to 9 switches can be stacked into one logical switch. All vswitches in the logical switch share the same configuration information and route information. The performance of a single vswitch is not affected when it is added to or removed from a logical switch.
Overlapping switches are connected through two loops. The hardware of the vswitch is responsible for Load Balancing data packets on the dual-Ring Road. Here, the loop acts as the backplane of this large logical switch. When both the dual-ring circuits work normally, the data packet transmission rate on this logical switch is 32 Gbps. When a data frame needs to be transmitted, the software of the switch calculates which loop is more available, and then the data frame is sent to the loop. If a stacked cable fails, the switch at both ends of the fault will detect the fault and disconnect the affected loop. The logical switch can still work in a single loop, the packet passing rate is 16 Gbps. The switch stack adopts the chrysanthemum link mode. For details about the connection mode, see. Www.2cto.com
When several switches are stacked, a switch is responsible for management, which is called the master switch. The master switch automatically updates the configuration file, route information, and stack information to other switches. The primary switch adopts a 1: N redundant backup mode. All switches in the stack can be used as the primary switch when the primary switch fails.
The master switch is responsible for downloading the CAM forwarding table to each vswitch. the routing information of the layer-3 switch is also maintained and distributed by the master switch. Other QoS features or access control list operations are also performed by the primary switch to inform other switches about the control. When a new switch is added or the existing switch is removed, the primary switch sends a notification, and other switches update their stack information accordingly.
Each vswitch on the ring has a MAC address table to save its local MAC address information. a mac table also maintains the MAC address information of other switches. The MAC address table is updated by the primary switch. In addition, the stack switch can process data packets in a very effective way. Each data packet has a 24-byte header information, including the packet destination information (this information is used in the stack switch, is provided by the main switch) and QoS indicator.
Www.2cto. comHSRP using hot backup for core switches is an inevitable choice to improve network reliability. When a core switch cannot work at all, all its functions are completely taken over by another backup router in the system until the faulty router returns to normal, this is the hot backup routing protocol (HotStandbyRouterProtocol ).
The condition for implementing HSRP is that there are multiple core switches in the system and they form a "hot backup group", which forms a virtual router. At any time, only one vro in A group is active and forwards data packets. If the active vro fails, a backup vro is selected to replace the active vro, however, in the view of hosts in the network, the virtual router has not changed. Therefore, the host is still connected and is not affected by the fault, which effectively solves the problem of switching the core switch.
To reduce network data traffic, after setting active core switches and backup core switches, only active core switches and backup core switches regularly send HSRP packets. If the active core switch fails, the backup core switch will take over as the active core switch. If the backup core switch fails or becomes an active core switch, another core switch is selected as the backup core switch.
We have already learned the differences above. The following illustration shows how HSRP works with Stack failover and data flow. Hot Backup routing protocol (HSRP) failover and data flow to HSRP under normal circumstances, data traffic trends
Under normal circumstances, when Terminal 1 accesses the application server, it first goes through the access layer switch 1, then to the core switch A, and through the core switch A to the application server, complete data exchange. When A line from an access layer switch to the primary core switch fails and switches to the standby server, the data flow goes to the data link connecting the access layer switch 1 to core switch, as a result, the data link of access layer switch 1 is switched to core switch B, but six data packets are lost at access layer switch 1, as shown in. Server link failure when the master link between the server and core switch A fails (such as A line or network card), when the master network card of the server switches to the backup network card, six data packets will be lost, however, after the master link is restored, the server will automatically switch from the slave Nic to the master Nic, but the data packets will not be lost during this switchover. The data flow of a specific terminal to access the server is shown in figure. When the main switch fails, when the core switch A fails, the access layer switch and server will switch from the main link to the standby link, but 6 packets will be lost during the switchover. The above are some of the performance of the hot backup routing protocol (HSRP) during the switchover after the link or device fails. Requirements for Stack failover and data stream stacking at www.2cto.com: the IOS version must be the same, the dedicated stack module and stack cable, and the maximum number of stacks should be 9
Stack advantages: high-density ports for ease of management (a switch is displayed during configuration, while ports of other switches are displayed with slot numbers) to avoid STP (Spanning Tree Protocol)
Note: 1. Stack a ring. Otherwise, only half of the bandwidth (16 GB) will be available ). 2. It is best to set the Priority of the switch you want to use as the master to a value of up to 15. The default value is 1 and the maximum value is 15. The larger the value, the higher the Priority. Data Traffic trends normally after stacking
A logical switch is formed after two or more Cisco Catalyst 3750 series switches are stacked when Cisco Catalyst 3750 series switches are used for stacking. All vswitches in the logical switch share the same configuration information and route information. The performance of a single vswitch is not affected when it is added to or removed from a logical switch.
The core switch, the access layer switch, and the server are interconnected through two links. The corresponding ports are bundled on the core switch and the access layer switch, which achieves double effect on the link, it can also avoid problems caused by STP (Spanning Tree. The uplink of the access layer www.2cto.com fails. When an uplink of the access layer with vswitch 1 fails, the data of the access layer 1 to the application server is not terminal, however, the bandwidth of the link is only halved. Server link failure: When a link between the server and the core switch fails, server packet loss does not occur. The failure of a single core switch www.2cto.com because the access layer switch and the Application Server both use dual-link mode to connect to the core switch, when one of the core switches fails, it will not cause packet loss to the entire network. I believe you can understand the differences between the two applications through the above figures!