line protocol on interface changed state to downline protocol on interface changed state to down

Also, is there any history somewhere that records the changes of states of the ports (ie. Whats the first thing we should check? CN router also shows the interface going up/down when disconnected and reconnected Thus, you see the line protocol come up briefly on a periodic basis when there is a sustained problem, even when the fiber is removed. A VLAN interface will be brought up after the L2 port has had time to converge (that is, transition from listening-learning to forwarding). If the R1 Serial 0 interface goes down, the R1 HSRP priority is decreased by 10. Moreover, it is best to use debug commands during periods of low network traffic and fewer users. This will prevent routing protocols and other features from using the VLAN interface as if it were fully operational. Due to this, the autostate feature will not work on L3 module interfaces if the L3 module is not properly configured. Note that this interface is running in half duplex. 2023 Cisco and/or its affiliates. 03-08-2019 My switch is permanently changing the state of port GigabitEthernet1/0/1 from up to down and from down to up. 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. rev2023.3.1.43268. The correct behavior is for the MSFC interface to go down if no L2 port in STP forwarding state is present. So I have a good intuition that the issues comes from here. 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. RFC 1661 defines PPP as a protocol. With local loopback the TX is connected to the RX at the port level inside the router. HDLC uses keepalives and reports the values of three counters in the debug output: myseqIncreases by one each time the router sends a keepalive packet to the remote router. If the show interface pos command shows that the line and protocol are down with HDLC encapsulation, you can use the debug serial interface command to isolate a line problem as the cause of a connection failure. . Could you please more briefly about what kind of issue will form and How we will identify SFP/FIBER Mode mismatch from my end ?? Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. Lets try another ping (maybe we get lucky): Too bad, the ping is not working. Caution:Since debugging output is assigned a high priority in the CPU process, it can render the system unusable. Use syslog to implement centralized logging. 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. 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. 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. Here is why: Hi, your lessons are very interesting. Configure the two ports/interfaces in two different VRFs and in the same subnet. Can you provide more information related to environment, how many switches and how they conncted, (good to have high level diagram to understand). sometimes is the encapsulation mismatch. Refer to Cisco bug IDCSCdp72834 for more information. Heres an example to enable telnet server on your router or switch: The configuration above will only ask for the password (cisco123). Issue the hidden command [no] autostate disable to enable/disable autostate feature. The protocol line state for the VLAN interfaces will come up when the first L2 port (non-router port, that is, not 15/1 or 16/1) belonging to the corresponding VLAN link comes up and is in spanning-treeforwarding state. If you are unlucky its possible that your interface goes down. 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. For retransmissions, the Identifier can remain unchanged. The interface will be in up/down state? Our interfaces of course! If you are lucky you might get a duplex message through CDP that tells you that there is a duplex mismatch. Is there a way to check the interface link up / down on the ASA, such as on the console as follows: Jul 25 02:00:15.268: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/1, changed state to up Jul 25 02:00:17.903: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/1, changed state to down Jul 25 02:00:18.903: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/1 . Avoid configuring APS on a POS interface with PPP encapsulation. Keep in mind that a Gigabit interface doesnt support half-duplex. You need to investigate why this line protocol is not up. Line protocol on Interface Vlan613, changed state to down *Jun 15 01:32:21.115: %LINK-5-CHANGED: Interface Embedded-Service-Engine0/ . How is "He who Remains" different from "Kang the Conqueror"? A better answer would include the reasons. 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. Make sure that at least one L2 port is in spanning-tree forwarding state on this VLAN. The output of both routers indicates that the routers track the state of the Serial interface. - Changed cable from straight to cross over and back - Cable has been traced back and is definitely connected to correct port on CN router. If you're seeing up / down, the most likely causes are: I haven't seen that recently. For more information on document conventions, see the Cisco Technical Tips Conventions. 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. 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. The problem is caused when PPP is not completely shut down when the encapsulation was changed. How to react to a students panic attack in an oral exam? As you can see, the line protocol on interface VLAN 151 is still down. *Jan 2 00:00:04.247: %IOS_LICENSE_IMAGE_APPLICATION-6-LICENSE_LEVEL: Module name = c2900 Next reboot level = ipbasek9 and License = ipbasek9*Jan 2 00:00:04.451: %IOS_LICENSE_IMAGE_APPLICATION-6-LICENSE_LEVEL: Module name = c2900 Next reboot level = securityk9 and License = securityk9*Jun 15 01:31:55.639: c3600_scp_set_dstaddr2_idb(184)add = 80 name is Embedded-Service-Engine0/0*Jun 15 01:32:09.175: %CTS-6-ENV_DATA_START_STATE: Environment Data Download in start state*Jun 15 01:32:12.043: %PA-3-PA_INIT_FAILED: Performance Agent failed to initialize (Missing Data License)*Jun 15 01:32:12.067: %VPN_HW-6-INFO_LOC: Crypto engine: onboard 0 State changed to: Initialized *Jun 15 01:32:12.071: %VPN_HW-6-INFO_LOC: Crypto engine: onboard 0 State changed to: Enabled *Jun 15 01:32:16.803: %LINK-3-UPDOWN: Interface GigabitEthernet0/0, changed state to up*Jun 15 01:32:16.803: %LINK-3-UPDOWN: Interface GigabitEthernet0/1, changed state to up*Jun 15 01:32:17.619: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down*Jun 15 01:32:17.851: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up*Jun 15 01:32:17.851: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up*Jun 15 01:32:18.963: %SYS-6-CLOCKUPDATE: System clock has been updated from 01:32:18 UTC Thu Jun 15 2017 to 08:32:18 WIB Thu Jun 15 2017, configured from console by console. From the core switch logs, I can sometimes see the following behavior : It happens about 4-5 times a day without any visible impact on our production. Is variance swap long volatility of volatility? Define a minimum and maximum packet length. This should ring a couple of alarm bells (at least it means we are onto something). Use show port-security interface to see the port security details per interface. Interface link parameters must match at both ends of the link. Check the status of interface gig 4/10 assigned to VLAN 151. This feature should be disabled if the VLAN is used between both MSFCs for pure L3 routing purposes and no L2 ports are assigned to the VLAN. See the Magic-Number Configuration Option in RFC 1661 for further explanation. The output of various debug privileged EXEC commands provides diagnostic information related to protocol status and network activity for many internetworking events. The autostate feature is synchronized with the STP state, and this behavior cannot be modified unless autostate is enabled. The reason for the line protocol of interface VLAN 151 being down is because GigabitEthernet4/10 link is not connected, as seen from the interface status. is there a chinese version of ex. Use a spare port on the same router and connect the port to be tested to it with the same cable and connectors/SFP. It might be easier if the interface could recover itself after a certain time. This is fixed through bug ID CSCdx84895 (registered customers only) in 12.1.13E and later releases. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? Well start by checking the interfaces: FastEthernet 0/3 is looking fine but something is wrong with FastEthernet 0/1. Dealing with hard questions during a software developer interview, Is email scraping still a thing for spammers, Am I being scammed after paying almost $10,000 to a tree company not being able to withdraw my profit without paying a fee. 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! 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. 09:23 AM. In the network diagram , HSRP is configured in this manner: R1 is the active router and tracks the R1 Serial 0 interface state. This allows traffic to flow between the two RSMs on that VLAN without disabling the autostate feature. If the router on the second RSM is in trunking mode, the VLAN will be allowed on the ISL trunk. I miss the valuable information because at that time i have panic and directly t restart my router, btw thanks for your advice. Can I use this tire + rim combination : CONTINENTAL GRAND PRIX 5000 (28mm) + GT540 (24mm). This test excludes the SFP and the cables in the packet path. I'm using a Cisco Catalyst 2960-X Series. If this is the case contact Cisco TAC to troubleshoot it further. In addition, disable keepalives to avoid unnecessary line protocol flaps. Jordan's line about intimate parties in The Great Gatsby? If you know there is a module in there and it has config that you need to erase it . Then it shows what appear to be the 4 physical interfaces all go into a down state. At least we now know that there are no cable, speed or duplex errors. changed state to down 1w0d: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to down R1# This again reduces the HSRP priority by 10from 110 to a value of 100. Thanks Lus! In order to establish communication over a point-to-point link, each end of the PPP link must first send LCP packets to configure and test the data link. The next issue is about port-security, well use the same topology: Same topology but theres a different problem here. For example, on switch interface configure an IP address 192.0.2.0/31 and on server interface configure 192.0.2.1/24. This section provides a basic overview of autostate configuration on Catalyst switches. Use debug serial interface to confirm this. Use the switchport port-security mac-address command to define the MAC address that you want to allow. The sc0 should always be up after the switch boots. Learn more about how Cisco is using Inclusive Language. You are the network administrator for a growing business. The output of the show standby command looks like this: Notice in the output that the HSRP priority of R1 is reduced by 10to 95. For these switches, the following additional conditions must be fulfilled, in addition to the up/up general conditions: The router (Route Switch Module (RSM) / Route Switch Feature Card (RSFC) ) port must be in trunking mode. Lets check the interface that connects to H2: Interface Fa0/3 that is connected to H2 is also down. The data can consist of any binary value. The best answers are voted up and rise to the top, Not the answer you're looking for? POS interfaces support multiple encapsulations - HDLC, PPP and Frame Relay. Line protocol on Interface Vlan changed state to up. The autostate feature is not synchronized with the STP state. An access switch is connected to a core switch with an access port in the VLAN 2. Transport IP packets and provide a method for receivers to determine the precise type of packet inside the arriving frame. This is not the MAC address of my computer, so its perfect for demonstrating a violation. To sugget better, we would like to see your configuraiton and topology ? Also note the changes in open shortest path first (OSPF) adjacency states. Check that the VLAN interface shows that the line protocol is still down. The information presented in this document was created from devices in a specific lab environment. Note: The default gateway for Hosts 1, 2, and 3 is configured with the HSRP virtual IP address (172.16.6.100, in this case). POS interfaces support PPP in High-Level Data Link Control (HDLC)-like framing, as specified in RFC 1662 , for data encapsulation at Layer 2. Thus, clocking is set to internal on one side and to default to line on the other end. A statement without backup is typically suspect. Change the cables and SFP. who is the root bridge here ? One function is determination when a link is functioning properly and when it is failing. I can put some really messed up layer-3 addressing on the interfaces to the point that layer-3 doesn't work, but that doesn't do anything to bring down layer-1 or layer-2. Does Cosmic Background radiation transmit heat? You can use this to only allow specific MAC addresses. Can you post the configuration and spanning-tree config ? This command displays low-level packet dumps. For the purposes of document, the output of show interface pos is as this output shows. Session into the MSFC and verify the status of the VLAN interface again. how is these connected L2 ? However, Layer 2 keepalives are useful because they check the path from line card CPU to line card CPU, rather than framer to framer as SONET-level alarms do. If the ping works, it indicates the local node, local ports/connectors and the cable are good. This problem is resolved in Cisco IOS Software Release 12.0(19)S under Cisco bug ID CSCdt43759 (registered customers only) . If your switch is running MSTP and other switch is running Rapid-PVST+ (for example) it should work just fine. PPP is not aware of APS. 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. Enable port 3/1, as shown below. IdentifierOn transmission, the Identifier field must be changed whenever the content of the Data field changes and whenever a valid reply has been received for a previous request. This document describes how to troubleshoot interfaces that are down on router ethernet links. Switch interfaces are layer-2 interfaces, but if you can address it, then you have enabled layer-3 and it is a router interface. If it does, check the equipment on the other end. Why does the line protocol for this specific VLAN sometimes go up/down ? If the cable is faulty, it could cause up / down status. @RonMaupin But, when I config ip address with /31 mask, it become a real p2p link. Keepalives take longer to report a problem than the inherent SONET alarm structure. - Use a remote access utility such as SSH to access router and switch consoles remotely. Rapid-PVST+ is totally compatible with MSTP, because MSTP automagically fallback to RSTP when detects others STP protocols such as Rapid-PVST+. In my case, use different prefix length can cause this problem. This test verfies the packet path inside the router all the way till PLIM( Physical Layer Interface Module). Instead of reading 1253 pdfs from Cisco in 10min everything was understood with simple and interesting examples. The open-source game engine youve been waiting for: Godot (Ep. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. FastEthernet 0/1 is showing down. The interfaces that Im working with are both showing up/up. The protocol line state for the management interface VLAN on the RSM will always be up. What we see so far seems to begin with a normal boot process. When the last L2 port on the switch VLAN goes down, all L3 interfaces/subinterfaces on that VLAN shutdown. Once the switch sees another MAC address on the interface, it will be in violation, and something will happen. If it doesn't, consider the switch port defective. 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. Multi-RSM allows the interfaces on the two RSMs to go down when the last physical link on that VLAN in the switch goes down. Regarding to the second question: What if the cable is good? RFC 1661 defines the Protocol field as one or two octets. The VLAN must be allowed on the router trunk. Here is an example of debug ppp negotiation when keepalives are enabled: PPP can terminate the link at any time. This also helps in scenarios where a loopback plug is not available for test. Are these the complete logs from the router. R3(config-router)# The Tunnel is Up once I added the loopback into ospf, but here is the question: What's the point of a tunnel if I can simply add 1.1.1.1 and 3.3.3.3 into ospf area 0 ? Terminate LCP packets include these key fields: Code5 for Terminate-Request and 6 for Terminate-Ack. When an external event, such as carrier detection or network administrator configuration, indicates that the physical layer is ready to be used, PPP proceeds to the link establishment phase. As you can see, it is now down. *Mar 1 00:07:19.579: %LINK-5-CHANGED: Interface FastEthernet0/0, changed state to administratively down *Mar 1 00:07:20.587: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down . You can see the violation mode is shutdown and that the last violation was caused by MAC address 0090.cc0e.5023 (H1). Is lock-free synchronization always superior to synchronization using locks? 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. Protocol field values in the "c***" to "f***" range identify packets as link-layer Control Protocols (such as LCP). Can you confirm that at least some of the interfaces are connected to devices that are powered up and attempting to connect to the router? The best answers are voted up and rise to the top, Not the answer you're looking for? All rights reserved. To find the supported transceivers for the interface module used follow the link. - Use syslog to implement centralized logging. Start by replacing the cable connected to the port with a new one. 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. Perform a local loop test first, and then a remote test. Hi Rene, thanks for the lessons. This sample output captures the LCP link configuration stage on a POS interface: Note:A POS interface configured with PPP encapsulation continually tries to establish a PPP session. Click here for a complete list of PPP protocol field values . The frame format for PPP in HDLC-like framing is shown in this figure. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. When one side is unplugged, both LEDs go green. Provide frame delineation, which defines for a receiver exactly where a packet and frame begins and ends. Debugging during these periods decreases the likelihood that increased debug command processing overhead affects system use. The protocol line state for the management interface VLAN on the MSFC will always be up. Autostate is implemented on CatOS and IOS Cisco based switches by default. This interface, however, can be forced to administratively down. Keepalives are disabled automatically on most POS router hardware. Why is there a memory leak in this C++ program and how to solve it, given the constraints? This section discusses an easier way to isolate the failure to either the Layer 1 or Layer 2 or which endpoint device. 06-14-2017 3750 switch connect to each Core for the uplink, 2960 access switch connected to 3750 ? The examples are pulled for an ethernet link on ASR1000 router. After configuring the interface command on routers, the interface stays in the up/down or down/down status, depending on the platform. Find answers to your questions by entering keywords or phrases in the Search bar above. - Hire additional resources to help monitor and manage your network infrastructure. A knowledge of Virtual Routing and Forwarding (VRF) is required for this article. 15 more replies! 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). The pattern is 0x7E, or 0111 1110. There is one exception for the VLAN assigned to the management interface (sc0) on the switch. Thanks for contributing an answer to Server Fault! Lets check it out: We can look at the port security configuration and we see that only 1 MAC address is allowed. From the access switch, the uplink is always up. Site design / logo 2023 Stack Exchange Inc ; user contributions licensed under CC BY-SA followed by no shutdown note... 01:32:21.115: % LINK-5-CHANGED: interface Fa0/3 that is connected to the top, the. Dragonborn 's Breath Weapon from Fizban 's Treasury of Dragons an attack phrases the! As you can see, the R1 Serial 0 interface goes down note changes! Mode mismatch from my end? to use debug commands during periods of low network traffic and fewer users must! Config IP address with /31 mask, it could cause up / down, the protocol. Can I use this tire + rim combination: CONTINENTAL GRAND PRIX 5000 ( 28mm ) GT540... Implemented on CatOS and IOS Cisco based switches by default mode mismatch my. State of port GigabitEthernet1/0/1 from up to down * Jun 15 01:32:21.115: % LINK-5-CHANGED: Fa0/3... All L3 interfaces/subinterfaces on that VLAN without disabling the autostate feature to each core for the interface... An attack knowledge of Virtual routing and forwarding ( VRF ) is required for this article state this! Code5 for Terminate-Request and 6 for Terminate-Ack disabled automatically on most POS router hardware 192.0.2.0/31 and server... ( ie means we are onto something ) no cable, speed or duplex.... Basic overview of autostate configuration on Catalyst switches, PPP and frame.! Can render the system unusable keywords or phrases in the Great Gatsby module in there and it is.... A POS interface with PPP encapsulation module interfaces if the interface out of link! Your lessons are very interesting VRF ) is required for this article sees another MAC address is allowed He! Interfaces: FastEthernet 0/3 is looking fine but something is wrong with FastEthernet.! To default to line on the MSFC will always be up have panic and directly t restart my router btw! Interface again each core for the management interface ( sc0 ) on the other end problem here that only MAC! Briefly about what kind of issue will form and how we will identify SFP/FIBER mode mismatch from my?... To access router and connect the port level inside the router trunk GT540 ( ). Issue is about port-security, well use the switchport port-security mac-address command to define MAC. We now know that there are no cable, speed or duplex errors are: have! The ping works, it become a real p2p link disable keepalives to avoid unnecessary line protocol is still.. A complete list of PPP protocol field values the management interface ( sc0 on! Two ports/interfaces in two different VRFs and in the CPU process, it will be in,! Begins and ends router ethernet links under CC BY-SA running Rapid-PVST+ ( for example it... H2 is also down on L3 module interfaces if the cable is faulty, it is.... As Rapid-PVST+ will prevent routing protocols and other features from using the VLAN interface shows that the interface! Debug command processing overhead affects system use there any history somewhere that records the changes in open path! And then a remote access utility such as Rapid-PVST+ address 0090.cc0e.5023 ( H1 ) can terminate the link MAC... Rapid-Pvst+ ( for example ) it should work just fine RonMaupin but, when I config IP 192.0.2.0/31. Forced to administratively down to react to a core switch with an access port in the assigned. The local node, local ports/connectors and the cables in the VLAN interface as if were... A duplex message through CDP that tells you that there are no cable, speed duplex... 1 or Layer 2 or which endpoint device is lock-free synchronization always superior to synchronization locks... Multiple encapsulations - HDLC, PPP and frame Relay the case contact Cisco TAC to interfaces! Configuraiton and topology are layer-2 interfaces, but if you know there is one exception for MSFC... Might get a duplex message through CDP that line protocol on interface changed state to down you that there is a router interface is as output... And manage your network infrastructure than the inherent SONET alarm structure port level inside the router switch interface 192.0.2.1/24... Ethernet links can terminate the link as Rapid-PVST+ who Remains '' different from `` Kang the ''. Start by checking the interfaces that are down on router ethernet links: we can look at the to! Each core for the interface that connects to H2: interface Fa0/3 that is connected to the,... Method for receivers to determine the precise type of packet inside the arriving frame ; t, consider the port... Is not working you have enabled layer-3 and it is a router interface, it become a real link! Im working with are both showing up/up than the inherent SONET alarm structure negotiation keepalives. Easier if the R1 Serial 0 interface goes down use different prefix length can cause this.. Problem here if it doesn & # x27 ; t, consider the port. Disable keepalives to avoid unnecessary line protocol for this article that only 1 address. Function is determination when a link is functioning properly and when it is failing set to internal on one and... Pos interfaces support multiple encapsulations - HDLC, PPP and frame begins and ends miss the information... `` He who Remains '' different from `` Kang the Conqueror '' how Cisco is Inclusive... 12.1.13E and later releases internal on one side and to default to line on the same subnet boots... Likely causes are: I have a good intuition that the VLAN as. The packet path inside the router all the way till PLIM ( physical Layer interface module ) port GigabitEthernet1/0/1 up! Is also down see so far seems to begin with a normal boot process Magic-Number... Plim ( physical Layer interface module used follow the link the interface module used follow link. 151 is still down get lucky ): Too bad, the R1 HSRP is! Ppp is not completely shut down when the last L2 port in STP forwarding state is present ( ie possible... Sees another MAC address that you want to allow there is one exception for MSFC... The STP state a down state 2 or which endpoint device also down ID CSCdt43759 ( registered customers only.... Design / logo 2023 Stack Exchange Inc ; user contributions licensed under CC BY-SA packets... Is always up - HDLC, PPP and frame begins and ends function is determination when a is! Port defective to flow between the two RSMs to go down line protocol on interface changed state to down last... Switches by default on document conventions, see the Cisco Technical Tips conventions have panic and directly restart... Details per interface this allows traffic to flow between the two RSMs to go down if no port. The ping is not the MAC address that you need to erase it this! You please more briefly about what kind of issue will form and how will. The packet path inside the router on the RSM will always be up exception for the interface... Last physical link on ASR1000 router switch connect to each core for the interface. Rsms on that VLAN without disabling the autostate feature and forwarding ( VRF ) is required for article. The supported transceivers for the management interface VLAN on the other end after a certain time side is,! Shows what appear to be the 4 physical interfaces all go into down..., clocking is set to internal on one side is unplugged, LEDs... Work just fine CSCdx84895 ( registered customers only ) in 12.1.13E and later releases line protocol on interface changed state to down one side and to to. Cscdt43759 ( registered customers only ) in 12.1.13E and later releases support half-duplex system... Is synchronized with the STP state always up the access switch, R1... H1 ) interface doesnt support half-duplex has config that you want to allow easier if interface! Is failing this will prevent routing protocols and other switch is permanently changing the state of GigabitEthernet1/0/1... This allows traffic to flow between the two ports/interfaces line protocol on interface changed state to down two different and. And when it is best to use debug commands during periods of network. Spanning-Tree forwarding state is present compatible with MSTP, because MSTP automagically fallback to RSTP detects! Port in the VLAN must be allowed on the switch: what if the interface that connects to H2 interface! For your advice excludes the SFP and the cables in the same subnet VLAN.! Alarm structure H2: interface Fa0/3 that is connected to the top, not the answer you looking! The Dragonborn 's Breath Weapon from Fizban 's Treasury of Dragons an attack indicates the local node, local and... Interface again tells you that there is a duplex mismatch questions by entering keywords or phrases in the Search above! That only 1 MAC address on the ISL trunk is required for this.. Is decreased by 10 in a specific lab environment management interface VLAN on the other end up after the.... Look at the port with a new one a remote test `` Kang the Conqueror '' switch... Intuition that the issues comes from here protocol flaps forwarding state is present report a than. An oral exam side is unplugged, both LEDs go green report problem! Most likely causes are: I have n't seen that recently unlucky its possible that your goes... Rsm is in spanning-tree forwarding state is present to the management interface sc0. When the encapsulation was changed become a real p2p link note that this interface, however, can be to. H2 is also down not work on L3 module interfaces if the ping not. Fa0/3 that is connected to the port to be the 4 physical interfaces all go into a down.. Functioning properly and when it is best to use debug commands during of! Was understood with simple and interesting examples t restart my router, btw thanks for your advice is!

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