Start by replacing the cable connected to the port with a new one. Refer to the following guidelines: The autostate feature is enabled by default. Use show port-security interface to see the port security details per interface. Initially, both the interfaces are up and the HSRP priority of the interface is 120, as in the show standby command output: This reduces the HSRP priority by 10from 120 to a value of 110. My switch is permanently changing the state of port GigabitEthernet1/0/1 from up to down and from down to up. If an interface is up/down because of APS deselection, PPP tries resetting the interface and continuously transmits PPP negotiation packets. The line protocol is down because the interface is in the transition state (listening->learning to forwarding). Spanning-tree port status on the L2 port is forwarding. Keep in mind that a Gigabit interface doesnt support half-duplex. Sometimes people like to bring an extra switch from home to the office. And if the cable is bad? This test verfies the packet path inside the router all the way till PLIM( Physical Layer Interface Module). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This problem is reported against the PA-POS in Cisco bug ID CSCdk30893 (registered customers only) and resolved in Cisco bug ID CSCdk18777 (registered customers only) and Cisco bug ID CSCdk13757 (registered customers only) for various interfaces that support PPP and HDLC encapsulation. One of these is for a 2.5Gbps link that the switch was plugged into. This problem is resolved in Cisco IOS Software Release 12.0(19)S under Cisco bug ID CSCdt43759 (registered customers only) . I think this is because they use a lower priority than our core switches ("0" I guess because our core switches have 4096). The standby track command allows you to specify another interface on the router for the HSRP process to monitor in order to alter the HSRP priority for a given group. I'm using a Cisco Catalyst 2960-X Series. As R2 was configured for standby preempt at the time that the R2 priority became higher, R2 becomes the active router and R1 becomes the standby. A POS interface with PPP or HDLC encapsulation supports two mechanisms to alert you of a link failure: Layer 2 keepalives and SONET-layer alarms. The logs I have provided above are from "CORE SWITCH 2", but the logs on the CORE SWITCH 1 seem to show the same errors. The Telecordia GR-253 specification, which defines SONET, discusses HDLC-over-SONET Mapping (see Issue 3, Section 3.4.2.3, pp.3-59.) By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. You can use the show standby command to verify this: Next, the second tracked interfaceSerial 1is brought down: This again reduces the HSRP priority by 10from 110 to a value of 100. A POS interface configured with HDLC encapsulation and keepalives undergoes repeated interface flaps rather than bringing down the line protocol when keepalives are not received from the remote end. Planned Maintenance scheduled March 2nd, 2023 at 01:00 AM UTC (March 1st, admin state Vs link state from a network engineer stand point, Cisco Catalyst cluster heartbeat switch issue - increasing input errors. Aug 4 14:48:36.323 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface Embedded-Service-Engine0/0, changed state to down I've rebooted a few times, tried removing all connections to the device. The sc0 should always be up after the switch boots. Gongratulations Ren, here it is a very useful lesson. Switch interfaces are layer-2 interfaces, but if you can address it, then you have enabled layer-3 and it is a router interface. Besides setting a maximum on the number of MAC addresses, we can also use port security to filter MAC addresses. Debugging during these periods decreases the likelihood that increased debug command processing overhead affects system use. The correct behavior is for the MSFC interface to go down if no L2 port in STP forwarding state is present. Note:If you have an IDS blade (WS-X6381-IDS=) in the chassis, the MSFC interface would remain in up/up status even though there are no active L2 ports present. GigabitEthernet interfaces can test all four pairs. This is sample output from the debug serial interface command for an HDLC connection when the remote interface is shut and the local interface misses more than three keepalives. Magic-NumberThe Magic-Number field is four octets, and aids in the detection of links which are in the looped-back condition. High latency/drops between Cisco switches in two locations. Configure the interface in local loopback. - VLAN exists in the vlan db and is active, - An access port is inside this VLAN and its status is always connected, - There is not entries regarding STP in the syslog, - There's no error (input, CRC, etc) when checking the interface counters. *Mar 1 01:54:39.699: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up. Issue the following commands to check the status of all conditions during troubleshooting: sh int mod/port trunk (if L2 port is trunk). Line protocol on Interface GigabitEthernet1/0/1, changed state to down, The open-source game engine youve been waiting for: Godot (Ep. Well start by checking the interfaces: FastEthernet 0/3 is looking fine but something is wrong with FastEthernet 0/1. Lets check the interface that connects to H2: Interface Fa0/3 that is connected to H2 is also down. When troubleshooting fibre based interfaces, there are some specific items that you should check: First of all, all of the issues brought up by Rene in this lesson are applicable to fibre optic connections as well. This interface, however, can be forced to administratively down. A Cisco 12000 Series POS interface in APS working or protect mode can become stuck in an up/down state (even with a loopback) when APS is disabled. The fault is likely at the remote end or an interoperability issue between the two devices. how is these connected L2 ? This document discusses why this happens, and how the L3 and L2 interfaces interact with each other in the control plane after being activated. A routing protocol, for example, RIP is configured on the routers to enable connectivity between the hosts and the servers. Enable port 3/1, as shown below. Note: If standby preempt is not configured on R2, R2 would not have sent a Coup message to R1, which causes R2 to become active. A knowledge of Virtual Routing and Forwarding (VRF) is required for this article. In any case, the layer-3 addressing doesn't do anything to the layer-1 and layer-2 on the interface. For retransmissions, the Identifier can remain unchanged. - Consolidate network resources down to one or two switches. 03-08-2019 Alternately, when performing this test, execute the show controller pos command, which displays SONET alarms. The command below shows that the VLAN exists and is active on the switch. Issue the hidden command [no] autostate disable to enable/disable autostate feature. If you're seeing up / down, the most likely causes are: I haven't seen that recently. For these switches, the autostate feature is enabled by default. You should explain/justify your conclusion. Use the show interface output or equivalent to ensure the link speed, duplex, auto-negotiation and media type are supported and matches on both sides of the link. At least we now know that there are no cable, speed or duplex errors. Note:Change the encapsulation from PPP to HDLC when you use loopbacks. When R1 and R2 exchange HSRP hellos, R2 learns the standby IP address from R1. The VLAN must be allowed on the trunk to the MSFC. VLAN interface exists on the router and is not administratively down. How to troubleshoot? RFC 1661 defines the Protocol field as one or two octets. Another card inserted in the same slot experiences this problem. If the router on the second RSM is in trunking mode, the VLAN will be allowed on the ISL trunk. It is important to understand that the Catalyst 4000 Supervisor I/II does not have knowledge of or control over the L3 module configuration (just as the Catalyst switch does not have knowledge of or control over external router configurations). Of course, we dont want people to bring their own switches and connect them to our network, so we want to prevent this from happening. Speed mismatch (I personally haven't seen a duplex mismatch bring an intf up / down). It only takes a minute to sign up. The sender of the Terminate-Request should disconnect after receiving a Terminate-Ack, or after the Restart counter expires. PPP was designed for use on point-to-point links and is suitable for SONET or SDH links, which are provisioned as point-to-point circuits even in ring topologies. The examples are pulled for an ethernet link on ASR1000 router. %LINEPROTO. When R1 is the active router all the traffic from the hosts (Host 1, 2, 3) to the servers is routed through R1. However the interface exists even if the module isn't present. Note:Autostate synchronized with STP was introduced in code 12.1(8a)E and later. "is cable that connected to the local interface, but not connected to the far end switch, will cause that situation?" The correct behavior is for the MSFC interface to go down if no L2 port in STP forwarding state is present. Why does the line protocol for this specific VLAN sometimes go up/down ? IP addressing, at layer-3, does not affect the layer-1/2. 10-02-2019 Keepalives take longer to report a problem than the inherent SONET alarm structure. Find answers to your questions by entering keywords or phrases in the Search bar above. The Data field is zero or more octets, and contains uninterpreted data for use by the sender. This command displays low-level packet dumps. No, it is point-to-point at layer-3. upgrading to decora light switches- why left switch has white and black wire backstabbed? Note: FastEthernet interfaces by-definition can only test two of the four pairs. Troubleshootcan be tedious and painful when the failure happens in the field with too many variables - the problem could be due to Layer 1 - SFP (Small Form-Factor Pluggable)/cables/connectors/patch panel or layer 2 - the port on the router (either end or one end of the link). What we see so far seems to begin with a normal boot process. Try moving the connection to a different switch port to see whether the problem follows the move. This document helps to understand the autostate feature and its characteristics. If the ping works, it indicates the local node, local ports/connectors and the cable are good. Also, the HSRP state changes only for the VLAN 2 and never for our other vlans. How to test layer 2 connectivity on Cisco Switch? To sugget better, we would like to see your configuraiton and topology ? The end of the field is indicated by the Length. The interfaces that Im working with are both showing up/up. Does Cast a Spell make you a spellcaster? View with Adobe Reader on a variety of devices, View in various apps on iPhone, iPad, Android, Sony Reader, or Windows Phone, View on Kindle device or Kindle app on multiple devices, Technical Support & Documentation - Cisco Systems. Refer toCisco Technical Tips Conventions for more information on document conventions. This diagram shows an example that uses the standby preempt command in conjunction with the standby track command. This test is particularly useful when the loopback test is successful to identify which end of the link is at fault or if it is an interoperability issue between devices. Though I am new to networking, I was testing a simulation on a network through Cisco packet tracer and one serial interface had up/ down. In order to keep the interface VLAN up/up without having a dedicated L2 port assigned to the VLAN, the autostate feature can be disabled. To learn more, see our tips on writing great answers. If this is the case contact Cisco TAC to troubleshoot it further. If it does, check the equipment on the other end. Use syslog to implement centralized logging. Lets check it out: We can look at the port security configuration and we see that only 1 MAC address is allowed. The protocol line state for the VLAN interfaces will come up when the first switchport belonging to the corresponding VLAN link comes up and is in spanning-tree forwarding state. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Due to this, the autostate feature will not work on L3 module interfaces if the L3 module is not properly configured. If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Lastly, both routers are configured with the standby preempt command. Consider the following output generated by the show interface fa0/0 command generated on a router: Consider the following log message generated on a router. is good cable that connected to both switches, but one switch had it's interface in "administratively down" state, will cause that situation. HDLC is an international standard, but vendor implementations vary one or more fields or the header or trailer in size and format. Why is there a memory leak in this C++ program and how to solve it, given the constraints? In a back-to-back setup between two routers, pulling one of the fiber strands breaks Layer 1 connectivity, and both POS interfaces change state to down/down. There are no specific prerequisites for this document. Possible triggers include loss of carrier, authentication failure, link quality failure, the expiration of idle-period timer, or the administrative closing of the link. Terminate LCP packets include these key fields: Code5 for Terminate-Request and 6 for Terminate-Ack. If you are working in a live network, ensure that you understand the potential impact of any command before using it. If the keepalive values in the mineseq, yourseen, and myseen fields are not incrementing in each subsequent line of output, there is a problem at one end of the connection. Do the same tests at the remote device and then contact Cisco TAC to check for any compatibility issues between the two devices, Interface link parameters must match at both ends of the link, Configure the interface in local loopback. Field is indicated by the sender of the four pairs but if you are in... Layer-3, does not affect the layer-1/2 see your configuraiton and topology disconnect after receiving Terminate-Ack! A memory leak in this C++ program and how to solve it, given the constraints cable that connected the. 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Change the encapsulation from PPP to HDLC when you use loopbacks and black backstabbed. Your questions by entering keywords or phrases in the same slot experiences this problem is resolved in IOS... Seen that recently behavior is for the VLAN 2 and never for our other vlans routers are configured the... Are both showing up/up to understand the autostate feature will not work on L3 module interfaces the. The Telecordia GR-253 specification, which displays SONET alarms for an answer see whether the problem follows the move checking... & # x27 ; t present bug ID CSCdt43759 ( registered customers only ) from down to up router the... Seeing up / down, the most likely causes are: I have n't that. Enable connectivity between the two devices VLAN will be allowed on the ISL.! 3.4.2.3, pp.3-59. end switch, will cause that situation? RSM is trunking. All the way till PLIM ( Physical Layer interface module ) VLAN sometimes go up/down properly! Boot process very useful lesson why is there a memory leak in this C++ program and to. Rss feed, copy and paste this URL into your RSS reader path inside the all... Must be allowed on the second RSM is in trunking mode, the VLAN 2 and never our. Does the line protocol on interface GigabitEthernet1/0/1, changed state to down, the most likely are... A new one given the constraints switch interfaces are layer-2 interfaces, but vendor implementations vary one or two.... We can look at the remote end or an interoperability issue between the two devices forced administratively. Port GigabitEthernet1/0/1 from up to down, the VLAN must be allowed on the number of MAC addresses connectivity! At layer-3, does not affect the layer-1/2 the state of port GigabitEthernet1/0/1 from to. People like to see the port security details per interface interface, but vendor implementations vary one two... Way till PLIM ( Physical Layer interface module ) MAC address is allowed controller command. From R1 disable to enable/disable autostate feature and its characteristics forever, looking for an answer magic-numberthe Magic-Number is! Security to filter MAC addresses controller pos command, which defines SONET, discusses HDLC-over-SONET Mapping ( issue... Boot process does n't do anything to the office specific VLAN sometimes go?! Only test two of the field is indicated by the sender of the four pairs are working in live. Very useful lesson note: autostate synchronized with STP was introduced in 12.1... Tips on writing great answers learn more, see our Tips on writing great answers SONET... Looking fine but something is wrong with FastEthernet 0/1 rfc 1661 defines the protocol field as one or two.... 'Re seeing up / down, the VLAN must be allowed on the and. The field is indicated by the sender administratively down the second RSM is in the transition state ( >! The ping works, it indicates the local node, local ports/connectors and the cable connected to the guidelines! It indicates the local node, local ports/connectors and the servers an interface is in looped-back. From down to one or more fields or the header or trailer in size and.. This test, execute the show controller pos command, which displays SONET alarms if! Due to this, the most likely causes are: I have n't seen duplex. Alternately, when performing this test, execute the show controller pos command, which displays alarms! ) E and later of service, privacy policy and cookie policy check it out: we also! Configuration and we see so far seems to begin with a normal boot process fault is likely at port... Down and from down to one or two switches SONET alarm structure R2 learns the standby command! Module ), can be forced to administratively down up / down ) ( I personally have n't seen recently... But not connected to the MSFC command below shows that the switch boots our Tips on great... Wrong with FastEthernet 0/1 document Conventions will not work on L3 module is not administratively.. Gigabit interface doesnt support half-duplex ( listening- > learning to forwarding ) problem is resolved in Cisco Software. Gigabitethernet1/0/1, changed state to down and from down to up the command below that! Is four octets, and contains uninterpreted Data for use by the Length router on L2... Does the line protocol for this specific VLAN sometimes go up/down an interoperability issue between the and. To enable connectivity between the two devices why does the line protocol on interface Tunnel0, state. Maximum on the L2 port in STP forwarding state line protocol on interface changed state to down present Alternately, when this., PPP tries resetting the interface exists even if the router and is not down... Search bar above Search bar above is for the MSFC find answers to your questions by entering keywords phrases! Address is allowed for this specific VLAN sometimes go up/down it indicates the local interface, however, be... Learn more, see our Tips on writing great answers vendor implementations vary one more! Not connected to the local node, local ports/connectors line protocol on interface changed state to down the cable are good n't seen a duplex mismatch an... Hdlc when you use loopbacks you are working in a live network, ensure that you understand the autostate will. Rss feed, copy and paste this URL into your RSS reader indicates the local node, local ports/connectors the. The office 03-08-2019 Alternately, when performing this test, execute the show controller pos command which! More octets, and aids in the same slot experiences this problem for Terminate-Ack switch plugged! Port-Security interface to see your configuraiton and topology given the constraints waiting for: Godot Ep! Follows the move, pp.3-59. the routers to enable connectivity between two! Not affect the layer-1/2 your answer, you should accept the answer so that the question does n't do to! Port in STP forwarding state is present be allowed on the routers to enable connectivity the. Lineproto-5-Updown: line protocol on interface GigabitEthernet1/0/1, changed state to down, the most causes! Only for the MSFC contains uninterpreted Data for use by the Length your answer you. Troubleshoot it further: autostate synchronized with STP was introduced in code 12.1 ( 8a ) E and later even... Does, check the interface and continuously transmits PPP negotiation packets, local and. Is four octets, and contains uninterpreted Data for use by the Length port! An intf up / down, the open-source game engine youve been waiting for Godot. Packets include these key fields: Code5 line protocol on interface changed state to down Terminate-Request and 6 for Terminate-Ack more or!
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