This feature helps you find ports that are incorrectly configured for PortFast. The output shows that the standby router moves from the standby state to the active state. The show standby command is a quick reference in order to view this information. A single router that is elected from the group is responsible to forward the packets that hosts send to the virtual router. A breakage can occur if someone bridges switches together with hubs or other switches and accidentally creates a physical loop. This timer is used in order to monitor the standby router. All of these problems affect the entire network, and especially HSRP. Vlan100 - Group 10 (HSRP-V2) (IPv4) Local state is Active, priority 130 (Cfged 130), may preempt. Change the speed and duplex settings for that port in order to help correct these errors. A mismatch of standby groups or HSRP standby addresses can cause HSRP problems. Hot Standby Router Protocol (HSRP) - Cisco The tie breaker is the router with the higher IP address. Refer to Hot Standby Router Protocol Features and Functionality for information on most of the HSRP features. interfaces on the router: If your router runs HSRP on several interfaces, you might want up numberThe valid range is from 1 to 255. These are details on the individual states: 0 - initial, 1 - learn, 2 - listen, 4 - speak, 8 - standby, and 16 - active. Here are some documents to help understand and configure these features: Configure Spanning Tree PortFast, BPDU Guard, BPDU Filter, UplinkFast, BackboneFast, and Loop Guard, Understand and Configure the Cisco UplinkFast Feature. ICMP redirect messages are automatically enabled on interfaces configured with HSRP. Table38-2 Commands for Displaying Tracking Information. This document is not restricted to specific software and hardware versions. Host C continues to use the IP address of the virtual router to address packets destined for Host B, which Router B now receives and sends to Host B. RFC 2281: Cisco Hot Standby Router Protocol (HSRP) - RFC Editor You can use the track ip route metric threshold global configuration command to determine if a route is above or below threshold. N7K Providing L3 with SVIs on 49 Vlans. The router sends periodic hello messages. Troubleshoot HSRP Problems in Catalyst Switch Networks - Cisco These messages specifically indicate that the router received a data packet that was sourced from the HSRP IP address on VLAN 25 with the MAC addresses 0000.0c07.ac19. Note: These examples configure static MAC addresses for illustration purposes only. When VTP Pruning is enabled in the network, it can cause the devices of an HSRP group to go active. The default display is detail. If it is configured to preempt, it becomes the active router, even though it is unable to provide adequate routing services. But, this is only a workaround for the error messages and actually hides the symptom of the problem. Here is an example: Unless HSRP is configured on a Token Ring interface, only use the standby use-bia command in special circumstances. This is the state at the start. The interface must be a valid interface that can support HSRP. If the error message is due to high CPU utilization, put a sniffer on the network and the trace the system that causes the high CPU utilization. To display Hot Standby Router Protocol (HSRP) information, use the show standby command in user EXEC or privileged EXEC mode. Note that the MAC addresses are not the same for each flow between the router and the host. You can display HSRP information for the whole switch, for a specific interface, for an HSRP group, or for an HSRP group on an interface. Verify Standby (HSRP) IP Addresses and Standby Group Numbers, 3. The debug enables you to determine if the HSRP router in question receives and transmits HSRP hello packets at specific intervals. This chapter describes how to use Hot Standby Router Protocol (HSRP) on the switch to provide routing redundancy for routing IP traffic not dependent on the availability of any single router. Solved: HSRP Active local, Standby unknown - Cisco Community The switch floods the packet that comes from host A and is destined for host B out all ports. A variety of problems can cause this behavior. Issue an IP ping from the associated router to the remote HSRP device. standby [group-number] track type number [interface-priority]. Here is an example: Verify that the configured standby (HSRP) IP addresses and standby group numbers match each HSRP-participating router. Packets from PC1 that are destined for PC2, HSRP virtual MAC address of Router A interface Ethernet 0 (0000.0c07.ac01), Packets that return through Router A from PC2 and are destined for PC1, Packets from PC1 that are destined for HSRP standby IP address (ICMP, Telnet), Packets that are destined for the actual IP address of the active router (ICMP, Telnet), Packets that are destined for the actual IP address of the standby router (ICMP, Telnet), Enables HSRP conditional debugging of the group (0255), Displays all HSRP errors, events, and packets, Display limited range of HSRP errors, events and packets. This is the basis of HSRP. To enable static NAT with HSRP support, issue the ip nat inside source static command with the redundancy keyword. If all other attempts to isolate or resolve HSRP fail, the "divide and conquer" method is the next approach. (Optional) group-numberThe group number to which the command applies. router is primary. Chng ta cng xem xt bi lab trong v d sau. A new standby router is also selected at that time. If no IP address is specified, the address is learned through the standby function. Verify that the specified objects are being tracked. Hot Standby Router Protocol (HSRP) l First Hop Redundancy Protocol (FHRP) c thit k cho php chuyn i d phng transparent ca thit b IP first-hop. HSRP uses this address and port to send hello packets between peers. The range is from 1 to 500. The switch also supports Multiple HSRP (MHSRP), an extension of HSRP that allows load sharing between two or more HSRP groups. You configure a Boolean expression to specify calculation by using either "AND" or "OR" operators. You want to see current HSRP information, such as which A software upgrade; refer to the bug for revision details. .168.1.2, priority 100 (expires in 7.776 sec) Standby router is local Priority 100 (default 100) Group name is "hsrp-Vl1-1" (default) SW2#show standby Vlan1 - Group 1 State is Active 2 state changes, last . The authentication string can be up to eight characters in length; the default string is cisco. Configure a switch-to-switch port channel as desirable on at least one side. The root bridge sets the TCN bit in the configuration BPDU. numberEnter the interface number (combined with interface type) that is tracked. On MSFC2, VLAN 2 is in the HSRP active state, and VLAN 1 is in the HSRP standby state. Note: The switch also counts STP bridge protocol data units (BPDUs) that are received and transmitted as multicast frames. Use the no standby [group-number] authentication string interface configuration command to delete an authentication string. standby [group-number] track object-number [decrement [priority-decrement]]. This example shows how to activate HSRP for group 1 on a port. To specify a virtual MAC address for the Hot Standby Router Protocol (HSRP), use the hsrp mac-address command in HSRP interface configuration mode. . A single VLAN that experiences an STP loop condition can congest a link and starve the other VLANs of bandwidth. When you measure the tracked list state by a weight threshold, you assign a weight number to each object in the tracked list. HSRP allows two or more HSRP-configured routers to use the MAC address and IP network address of a virtual router. You can also specify whether to display a concise overview of HSRP information or detailed HSRP information. Refer to Recover Errdisable Port State on Cisco IOS Platforms for more information. Possible values are: 0 - hello, 1 - coup, and 2 - resign. Issue the show access-lists command as a quick reference to note the access lists that are configured on the router. This timer is used to clock hello packets. Updated technical content to make current. Because of the load-balancing nature of Fast EtherChannel (FEC) (port-channeling), FEC issues can contribute to both HSRP and STP problems. Solved: HSRP-Issue: Both Routers Active - Cisco Community Examples include the Cisco LocalDirector and Cisco Cache Engine. Packets from the host machines that are destined for the HSRP IP address have the destination MAC address of the HSRP virtual MAC address. Each standby group emulates a single virtual router (default gateway). Specify the object to be tracked. The preferable method is to change the MAC aging time to 14,400 seconds. Issue the show standby command in order to verify connectivity. For each interface configured for hot standby, you can configure a separate list of interfaces to be tracked. If the active router fails, the standby assumes the packet forwarding duties. In addition, note any errors in the switch log and reference additional case studies as necessary. The active timer then starts. The next hop IP address is changed to an HSRP virtual address. Otherwise, the standby timer is set to the current hold time value that is in use by this router. The range is from 1 to 255; the default is 10. This problem can occur with Fast Ethernet interfaces at the disruption of network connectivity or at the addition of an HSRP router with higher priority to a network. See the "Configuring Layer 3 Interfaces" section. Note Repeat this step for each interface to be tracked. Normally, the holdtime is greater than or equal to 3 times the hellotime. The show interfaces controllercommand notes which ports transmit or receive an excessive number of packets. Lrn-Discrd, In-Lost, and Out-Lost count the number of packets that are mistakenly forwarded or dropped due to insufficient buffers. Resign messages are sent when a router no longer wishes to be the active router. If one switch port is configured for autonegotiation, the other side of the link must also be configured for autonegotiation. These packets are sent to the destination IP multicast address 224.0.0.2 on User Datagram Protocol (UDP) port 1985. This output shows that the last topology change occurred from device connected off interface GigabitEthernet1/0/35. This table shows the format of the data portion of the UDP HSRP frame: This table describes each of the fields in the HSRP packet: Each router only uses three timers in HSRP. Configure an interface to track other interfaces so that if one of the other interfaces goes down, the device's Hot Standby priority is lowered. If the list is up, the list detects that object 2 is down: To track by weight threshold, configure a tracked list of objects, specify that weight is used as the threshold, and configure a weight for each of its objects. You can use interface and/or HSRP group conditional debugging in order to filter this debug output. show track ip [object-number] [brief] route. (Optional) group-numberThe group number on the interface for which HSRP is being enabled. When to Use the standy use-bia Command, B. Verify Catalyst Fast EtherChannel and Trunking Configuration, 2. keywords displays all of the HSRP information for all groups and All HSRP routers in any HSRP state generate a hello packet when this hello timer expires. After STP is allowed to reconverge on the new nonredundant topology, reattach one redundant link at a time. To increase the Selective Packet Discard (SPD) size, go to the configuration mode and execute these commands on the Cat6500 switches: In order to increase the hold queue size, go to the VLAN interface mode and execute this command: After you increase the SPD and hold queue size, you can clear the interface counters if you execute the clear counter interfacecommand. During normal operation, the two routers share the IP traffic load. Note: Enable STP for all VLANs at all times, regardless of whether there are redundant links in the network. To do so, specify a group number for each Hot Standby command group you configure for an interface. The Inand Outcolumns indicate the number of unicast, multicast, and broadcast packets that are received and transmitted on a particular port. Enter list to track objects grouped in a list. You can configure MHSRP to achieve load balancing and to use two or more standby groups (and paths) from a host network to a server network. This command tells the router to use its BIA instead of the virtual HSRP MAC address for the HSRP group. The state of the tracked list is determined by whether or not the threshold was met. Specify the object to be tracked. hsrp mac-address. Track Option in HSRPv2 Configuration Example. Break FEC ports into single connected ports. Also, verify that each interface has the line protocol up. The error messages signify the loss of HSRP hellos between the peers. Sniffer trace that shows that packets on the host port are not destined for the host, Increased network latency with L2-based packet rewrite engines, such as server load balancers, web cache devices, and network appliances. Display information about tracked IP-route objects. Configuring and Troubleshooting Ethernet 10/100/1000Mb Half/Full Duplex Auto-Negotiation, Recover Errdisable Port State on Cisco IOS Platforms, Troubleshooting Cisco Catalyst Switches to NIC Compatibility Issues, The Understanding Data Link Errors section of Troubleshooting Cisco Catalyst Switches to NIC Compatibility Issues, Troubleshooting Switch Port and Interface Problems. Follow these guidelines when configuring HSRP: HSRP can be configured on a maximum of 32 VLAN or routing interfaces. When you troubleshoot STP issues, disable all advanced STP (UplinkFast and BackboneFast). If the link is configured to be a trunk, be sure that both sides of the trunk carry the same VLANs. (Optional) Save your entries in the configuration file. Also, verify that the UDP traffic that is destined for the HSRP port 1985 is not filtered. By default, a port security violation causes the switch interface to become error-disabled and to shutdown immediately, which blocks the HSRP status messages between the routers. Figure38-1 shows a segment of a network configured for HSRP. For example, when tracking multiple interfaces using the "AND" operator, up means that all interfaces are up and down means that at least one interface is down. Verify IP connectivity. But, slow network performance and packet loss can result from the network instability that causes the STANDBY-3-DUPADDR error messages of the HSRP address. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product.