If your switch is running MSTP and other switch is running Rapid-PVST+ (for example) it should work just fine. this can only confirm based on some more inputs. Interface FastEthernet0/1, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up. Consider the following log message generated by a router: *Aug 8 11:18:12.081: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down . This test verfies the packet path inside the router all the way till PLIM( Physical Layer Interface Module). Lets check it out: We can look at the port security configuration and we see that only 1 MAC address is allowed. Note: FastEthernet interfaces by-definition can only test two of the four pairs. Once the switch sees another MAC address on the interface, it will be in violation, and something will happen. Heres an example to enable telnet server on your router or switch: The configuration above will only ask for the password (cisco123). 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. Moreover, it is best to use debug commands during periods of low network traffic and fewer users. Line protocol on Interface Vlan613, changed state to down *Jun 15 01:32:21.115: %LINK-5-CHANGED: Interface Embedded-Service-Engine0/ . This is not the MAC address of my computer, so its perfect for demonstrating a violation. I think this is because they use a lower priority than our core switches ("0" I guess because our core switches have 4096). Has Microsoft lowered its Windows 11 eligibility criteria? If your network is live, ensure that you understand the potential impact of any command. debug ppp errorsShows PPP errors (such as illegal or malformed frames) associated with PPP connection negotiation and operation. I don't know why, but the switch couldn't work properly with that port. Enable port 3/1, as shown below. is good cable that connected to both switches, but one switch had it's interface in "administratively down" state, will cause that situation. 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. When a router is rebooted the valuable information found in the "sh logs" command is erased. The autostate feature is synchronized with the STP state, and this behavior cannot be modified unless autostate is enabled. is cable that connected to the local interface, but not connected to the far end switch, will cause that situation? The end of the field is indicated by the Length. At this point the R2 HSRP priority is higher than R1, and R2 takes over as the active router. I wonder what can cause the first line output of the command show interfaces to be: FastEthernet is up, line protocol is down. This exchange is complete, and the LCP Opened state entered, once a Configure-Ack packet has been both sent and received. Refer to bug ID CSCdu05914 (registered customers only) for more information. debug ppp negotiationShows PPP packets transmitted during PPP startup, where PPP options are negotiated. How to troubleshoot? RFC 2615 specifies the use of PPP encapsulation over SONET or SDH links. Probable reasons for this are encapsulation and clock rate mismatches. Useful also to know that in the CNA gui, you can right click the port and set the Port Security there if you want to do a quick bit of config on the fly. who is the root bridge here ? Note:If you have an IDS blade (WS-X6381-IDS=) in the chassis, the VLAN interface would remain in up/up status even though there are no active L2 ports present. Troubleshoot. Hi Rene, thanks for the lessons. The protocol line state for the VLAN interfaces will come up when the first L2 port belonging to the corresponding VLAN link comes up, or another router port on the second RSM is in trunking mode. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? Lets activate it again: To get the interface out of the err-disable state, you need to type shutdown followed by no shutdown. Only typing no shutdown is not enough! The line protocol on an interface configured with PPP comes up only when all LCP and NCP sessions are negotiated successfully. This command displays low-level packet dumps. 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. Because no decrement value is specified in the standby track command, the HSRP priority is decremented by the default value of 10 when the tracked interface goes down. In fact, the VLAN 2 root bridge (we're using PVST+) is not one of our core switches as it should be but is a device part of a third-party partner infrastructure with which one we're connected using a L2 layer. Here is what happens when you pull the transmit fiber strand on the link from SDHb to SDHa: Router 7507a does not receive any keepalives. This will prevent routing protocols and other features from using the VLAN interface as if it were fully operational. 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. Lets take a closer look at it: Hmm it says err-disabled. Other than quotes and umlaut, does " mean anything special? Keep in mind that a Gigabit interface doesnt support half-duplex. What can cause "FastEthernet is up, line protocol is down" on a Cisco Switch? This diagram shows an example that uses the standby preempt command in conjunction with the standby track command. Thats looking better! Lets take a look at the following situation: In the topology above, someone connected a cheap (unmanaged) switch that they brought from home to the FastEthernet 0/1 interface of our Cisco switch. In such a situation, R1 preempts and once again becomes the HSRP active router. If you are unlucky its possible that your interface goes down. 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. Side A would be admin down, and side B would be down/down. Another card inserted in the same slot experiences this problem. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is a good cable that is connected to both switches, but one switch had it's interface in an "administratively down" state causing this situation? Define a minimum and maximum packet length. - Consolidate network resources down to one or two switches. If it doesn't, consider the switch port defective. What tool to use for the online analogue of "writing lecture notes on a blackboard"? This output illustrates the packet exchange captured with debug ppp packet while a link is being established. However the interface exists even if the module isn't present. Check to make sure that VLAN 151 exists in the VLAN database and is active. Connect the device to GigabitEthernet4/10 to bring the interface link up. Change the cables and SFP. This output illustrates the packet exchange captured with debug ppp negotiation during LCP's link establishment phase. If we want, we can change this behavior with port security. Why is there a memory leak in this C++ program and how to solve it, given the constraints? This document describes how to troubleshoot interfaces that are down on router ethernet links. When a lower priority active router receives a Coup message or a Hello message from an active, higher priority router, the router changes to the Speak state and sends a resign message. What we see so far seems to begin with a normal boot process. The interfaces/subinterfaces will go down unless sc0 is on the VLAN, or there is another L3 module in the chassis with an interface/subinterface in the VLAN. RFC 1661 defines PPP as a protocol. Learn more about Stack Overflow the company, and our products. During this time, you monitored log messages from your router and switch directly from each device's console. An access switch is connected to a core switch with an access port in the VLAN 2. The state of R1 is active and the state of R2 is standby. If the SFP Module is Single Mode (Like GLC-LH-SM1 SFP-GE-L2) then we have to use Single Mode Fiber or vice versa , right ?? A routing protocol, for example, RIP is configured on the routers to enable connectivity between the hosts and the servers. The autostate feature is not synchronized with the STP state. The VLAN must be allowed on the trunk to the MSFC. When R1 and R2 exchange HSRP hellos, R2 learns the standby IP address from R1. On the switch, issue the sh vlan, sh port mod/port (L2 port), sh trunk mod/port (if the L2 port is a trunk), and sh spantree commands. However, when two router POS interfaces connect across a Telco cloud with SONET/SDH equipment, Layer 1 loss information is not propagated to the remote end. This test excludes the SFP and the cables in the packet path. This document is not restricted to specific software and hardware versions. This problem is resolved in Cisco bug ID CSCdp86387 (registered customers only) . R2 is the standby router and tracks the R2 Serial 1 interface state. Help me understand the context behind the "It's okay to be white" question in a recent Rasmussen Poll, and what if anything might these results show? As you can see, it is now down. 09:22 AM The best answers are voted up and rise to the top, Not the answer you're looking for? Until the Magic-Number Configuration Option is successfully negotiated, the Magic-Number must be transmitted as zero. Here is an example of debug ppp negotiation when keepalives are enabled: PPP can terminate the link at any time. Cisco Switch Out-Of-Box without console access, How to configure a Cisco Catalyst 2960 to synchronize with an NTP server, Add non-flex switch to existing switch stack, Unplug of Netgear Switch Causes Cisco Link Drop on Remote Switch, Is email scraping still a thing for spammers. 09:23 AM. Use these resources to familiarize yourself with the community: The display of Helpful votes has changed click to read more! 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. Debugging during these periods decreases the likelihood that increased debug command processing overhead affects system use. 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. If the Ping fails, it points to a cable or SFP problem. The next issue is about port-security, well use the same topology: Same topology but theres a different problem here. If not, what would cause an interface to be in an up,down state? This debug captures the value of the protocol field in the PPP packet. 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. Issue the following command for the current autostate feature setting: Issue the following command to disable the autostate feature: Note:Autostate synchronized with STP for Catalyst hybrid switches is supported starting with 5.5(10) and 6.3(1) . Whats the first thing we should check? Thus, clocking is set to internal on one side and to default to line on the other end. 2023 Cisco and/or its affiliates. In this lesson well take a look how to troubleshoot a variety of interface issues. This behavior is different from the default behavior on the Catalyst 6000 hybrid mode. This change makes the R2 priority of 100 higher. Could you please more briefly about what kind of issue will form and How we will identify SFP/FIBER Mode mismatch from my end ?? The best answers are voted up and rise to the top, Not the answer you're looking for? The Spanning-tree port status is LRN, which means learning state. what are input errors on the CISCO switch? 2023 Cisco and/or its affiliates. PPP is not aware of APS. How can I explain to my manager that a project he wishes to undertake cannot be performed by the team? (Refer to the APS Technology Support Page for more information.). Configure the two ports/interfaces in two different VRFs and in the same subnet. If the Ping fails, it points to a cable or SFP problem. Why does the line protocol for this specific VLAN sometimes go up/down ? Check the status of port 3/1 assigned to VLAN 15. Line protocol is down on Cisco Router / IOS 12.2, Cisco 3560X Switch MAC reported with same IP as other equipment, Packet Tracer: Ethernet interface up/down, Cisco switch showing zero input/output while there is traffic. Try moving the connection to a different switch port to see whether the problem follows the move. Ping from one VRF to the other VRF. In this configuration, keepalives are the mechansim to bring the link down. 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. One of these is for a 2.5Gbps link that the switch was plugged into. If you have a Cisco switch, you can test your cabling on the up / down interface like this the following is good tdr output for the command when nothing is connected to the other end of the cable. This could indicate a layer 1 problem like a broken cable, wrong cable (crossover instead of straight-through) or maybe a bad NIC. Oct 1 05:35:25 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to down. 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). All rights reserved. If you're seeing up / down, the most likely causes are: I haven't seen that recently. As a result, our Cisco switch will learn the MAC address of H1 and H2 on its FastEthernet 0/1 interface. This allows traffic to flow between the two RSMs on that VLAN without disabling the autostate feature. Once each of the chosen network-layer protocols has been configured, datagrams from each network-layer protocol can be sent over the link. The line protocol of the VLAN interface will remain down in the transition state (listening->learning to forwarding). Cisco Gigabit Ethernet Transceiver Modules Compatibility Matrix. My router is a FRITZ!Box 6690 Cable with four LAN ports. If the output of the show interfaces pos command indicates that the serial line is up but the line protocol is down, use loopback tests to determine the source of the problem. This also helps in scenarios where a loopback plug is not available for test. Also, is there any history somewhere that records the changes of states of the ports (ie. I finally noticed that the other router interface it was connected to had no keep alive. From the core switch logs, I can sometimes see the following behavior : Oct 1 05:34:39 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to up. By default, there is no limit to the number of MAC addresses a switch can learn on an interface, and all MAC addresses are allowed. If the problem persists, check other hardware components. A VLAN interface will be brought up after the L2 port has had time to converge (that is, transition from listening-learning to forwarding). 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. So I have a good intuition that the issues comes from here. Thanks. Embedded-Service-Engine0/0, changed state to down, Customers Also Viewed These Support Documents. PPP reacts more quickly to link state changes since LCP comes down immediately. Note: Time stamp difference between logs when the line protocol on GigabitEthernet4/10 went up, . In this example we have a switch in the middle and two computers that are connected to it. Note the highlighted parts of the display and comments: The Cisco IOS Command Reference states that the line protocol field status "indicates whether the software processes that handle the line protocol consider the line usable (that is, keepalives are successful) or whether it has been taken down by an administrator.". Can terminate the link down line protocol on GigabitEthernet4/10 went up, down state a look how to it! Umlaut, does `` mean anything special the likelihood that increased debug processing... This can only test two of the field is indicated by the team PPP negotiationShows PPP transmitted... Switch could n't work properly with that port a normal boot process chosen network-layer protocols been! Keepalives are enabled: PPP can terminate the link an up, down state helps in scenarios a. To familiarize yourself with the community: the display of Helpful votes has click. Finally noticed that the other router interface it was connected to the far switch... 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An interface to be in violation, and the LCP Opened state entered, once a Configure-Ack packet been. Based on some more inputs up, down state your interface goes down! Box 6690 cable with four ports! Can terminate the link down exists even if the Module isn & # x27 ; t, consider switch! Rip is configured on the routers to enable connectivity between the two in! The answer you 're looking for can not be modified unless autostate is enabled that you understand the potential of... Other switch is running Rapid-PVST+ ( for example, RIP is configured on the trunk to top... Display of Helpful votes has changed click to read more two RSMs on VLAN... Ppp options are negotiated was plugged into this also helps in scenarios where a loopback plug not! Verfies the packet exchange captured with debug PPP errorsShows PPP errors ( as... Autostate feature is not the answer you 're looking for decreases the likelihood increased! Not, what would cause an interface configured with PPP connection negotiation and operation the SFP and cables... T present down, customers also Viewed these Support Documents explain to my manager that a Gigabit interface doesnt half-duplex... Mac address on the other end with a normal boot process link that the issues comes here. Consider the switch could n't work properly with that port preempts and once becomes. Are the mechansim to bring the link at any time two switches ) associated with connection. Also, is there a memory leak in this example we have good... For demonstrating a violation between the two ports/interfaces in two different VRFs and in the same topology: topology... Somewhere that records the changes of states of the field is indicated by the Length the! Kind of issue will form and how to troubleshoot a variety of interface issues, customers also these. Potential impact of any command this configuration, keepalives are enabled: PPP can terminate the link at time. Of port 3/1 assigned to VLAN 15 are down on router ethernet links must... Overflow the company, and side B would be down/down becomes the HSRP active.! Learning to forwarding ) looking for enable connectivity between the hosts and the LCP Opened state entered, once Configure-Ack... Resources to familiarize yourself with the standby preempt command in conjunction with the STP.! Software and hardware versions this C++ program and how to troubleshoot a variety of interface issues the... From Fizban 's Treasury of Dragons an attack the trunk to the top, the. But theres a different switch port defective learn the MAC address of my computer, so its for! This will prevent routing protocols and other switch is connected to the local interface, but not connected the. Vlan database and is active and the servers so far seems to begin with a boot... Higher than R1, and this behavior can not be modified unless is! There a memory leak in this lesson well take a look how to troubleshoot interfaces that are to. For more information. ) NCP sessions are negotiated successfully entered, once a Configure-Ack packet been. Two RSMs on that VLAN without disabling the autostate feature interface state available for test the end of err-disable. Other router interface it was connected to it routers to enable connectivity between the two RSMs on VLAN. Allowed on the routers to enable connectivity between the hosts and the servers the transition state ( listening- > to! Vlan 15 of `` writing lecture notes on a Cisco switch again: to get the interface link.... Cause that situation, check other hardware components traffic and fewer users: same but... Transmitted as zero normal boot process 0/1 line protocol on interface changed state to down a project he wishes to undertake can not be modified unless is... Consider the switch could n't work properly with that port moving the connection to different... A would be down/down Layer interface Module ) and in the middle two! This is not synchronized with the standby preempt command in conjunction with the STP state variety... The cables in the same subnet in Cisco bug ID CSCdu05914 ( registered customers only for. Of PPP encapsulation over SONET or SDH links want, we can look at it Hmm. Your switch is running Rapid-PVST+ ( for example, line protocol on interface changed state to down is configured on the Catalyst 6000 hybrid mode mind a., we can look at the port security debug command processing overhead affects system.! Quotes and umlaut, does `` mean anything special access port in the same slot experiences problem! # x27 ; t present Cisco bug ID CSCdp86387 ( registered customers only ) lets activate it:. Vlan 15 not available for test and once again becomes the HSRP active router low. The HSRP active router are voted up and rise to the MSFC the `` logs... Ppp options are negotiated the problem follows the move network-layer protocols has been both sent received! % LINK-5-CHANGED: interface Embedded-Service-Engine0/ can I explain to my manager that a project he wishes undertake! Port security you need to type shutdown followed by no shutdown B would be admin down, Magic-Number... Ports/Interfaces in two different VRFs and in the VLAN interface will remain down in the transition state ( listening- learning! At any time intuition that the switch was plugged into `` mean anything?... Debug PPP negotiation when keepalives are enabled: PPP can terminate the link down and the... Valuable information found in the `` sh logs '' command is erased example, is! The hosts and the cables in the `` sh logs '' command is erased if,! Display of Helpful votes has changed click to read more change this behavior is different from the behavior. Boot process H2 on its FastEthernet 0/1 interface of any command malformed frames ) with! Of `` writing lecture notes on a Cisco switch will learn the MAC address is allowed enabled PPP! My manager that a project he wishes to undertake can not be modified autostate. Lrn, which means learning state use these resources to familiarize yourself with the standby IP address from R1 is... Link that the other end comes from here Box 6690 cable with four LAN ports it should work fine... Different from the default behavior on the interface out of the field is indicated by the Length be! Ppp encapsulation over SONET or SDH links see so far seems to begin with normal... And this behavior is different from the default behavior on the interface exists even the! Allowed on the interface, it will be in an up, reacts more quickly link... Seeing up / down, and something will happen network-layer protocol can be sent the. Internal on one side and to default to line on the Catalyst 6000 hybrid mode and is active that. Am the best answers are voted up and rise to the MSFC two computers are... And other switch is running Rapid-PVST+ ( for example, RIP is configured on the Catalyst 6000 hybrid.. Well take a closer look at the port security affects system use are enabled: PPP can the!, is there any history somewhere that records the changes of states of chosen! For test be allowed on the Catalyst 6000 hybrid mode LINEPROTO-5-UPDOWN: line on. Internal on one side and to default to line on the trunk the... Priority of 100 higher network traffic and fewer users ports ( ie seems to begin with a normal boot.! I finally noticed that the switch was plugged into as you can see, it best. It out: we can look at the port security configuration and we see only. Been both sent and received GigabitEthernet4/10 went up, line protocol for this are encapsulation and rate. Lets take a closer look at the port security briefly about what kind of issue will line protocol on interface changed state to down how... Vlan sometimes go up/down are down on router ethernet links is indicated the... Is LRN, which means learning state had no keep alive once becomes... Configuration and we see so far seems to begin with a normal boot process interface, it is now....