Click the card to flip Definition 1 / 4 On MSFC, issue the show int vlan command. (Refer to the APS Technology Support Page for more information.). 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. Learn more about how Cisco is using Inclusive Language. is this correct. If you're seeing up / down, the most likely causes are: I haven't seen that recently. how is these connected L2 ? 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. Refer to the following guidelines: The autostate feature is enabled by default. The interface will be in up/down state? There is one exception for the VLAN assigned to the management interface (sc0) on the switch. Note the changes in line protocol status on both interfaces when the APS switchover occurs. This test excludes the SFP and the cables in the packet path. The number of distinct words in a sentence. Issue the following command to see what Catalyst 4000 L3 services module interfaces have been shut down or brought up by the autostate feature: Issue the following command to disable the autostate feature (this is a hidden command): Issue the following command to re-enable the autostate feature: Perform these troubleshooting steps if the VLAN interface is down. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. IP addressing, at layer-3, does not affect the layer-1/2. Find answers to your questions by entering keywords or phrases in the Search bar above. Lets see why it is disabled: Use the show interfaces status err-disabled command to see why the interface got into error-disabled mode. Are these the complete logs from the router. If not, what would cause an interface to be in an up,down state? Lets take a closer look at it: Hmm it says err-disabled. 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 ? This interface, however, can be forced to administratively down. View with Adobe Reader on a variety of devices, Understanding Loopback Modes on Cisco Routers, Technical Support & Documentation - Cisco Systems, Configure-Request, Configure-Ack, Configure-Nak and Configure-Reject, Code-Reject, Protocol-Reject, Echo-Request, Echo-Reply, and Discard-Request. When you finish using a debug command, remember to disable it with its specific no debug command or with the no debug all command. - Use syslog to implement centralized logging. 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. ASR 1000 Series Aggregation Services Routers. This section discusses an easier way to isolate the failure to either the Layer 1 or Layer 2 or which endpoint device. Protocol field values in the "c***" to "f***" range identify packets as link-layer Control Protocols (such as LCP). To find the supported transceivers for the interface module used follow the link. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. There is one exception for the VLAN assigned to the management interface (sc0) on the switch. Protocol field values in the "0***" to "3***" range identify the network-layer protocol of specific packets, and values in the "8***" to "b***" range identify packets belonging to the associated Network Control Protocols (NCPs), if any. Refer to Cisco Technical Tips Conventions for more information on document conventions. Ping from one VRF to the other VRF. This may have solved the problem but it doesn't give us any details to start any troubleshooting process. What happens if the serial 0 interface of R1 goes down? In the question, the interface is layer-1, and the line protocol is layer-2. Magic-NumberThe Magic-Number field is four octets, and aids in the detection of links which are in the looped-back condition. The sc0 should always be up after the switch boots. I found the problem! 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 document describes how the standby preempt and standby track commands work together and how to use them. Lets check the interface that connects to H2: Interface Fa0/3 that is connected to H2 is also down. 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. It is possible that no device is connected to the interface or that the link has cabling or auto-negotiation issues preventing the link from being up. from 2960 to 3750 to Core ? if the cable is good, both sides will be down. mineseenValue of the mineseen counter reflects the last myseq sequence number the remote router has acknowledged receiving from the router. Instead R1 would have remained the active router. I configured port security in the example above, so it only allows MAC address aaaa.bbbb.cccc. Alternatively, you can post and accept your own answer. Older switches don't have a tdr function you'd have to test the cabling manually. 2023 Cisco and/or its affiliates. Additionally, you should keep the following in mind when troubleshooting fibre based interfaces: Hi Laz, Refer to bug ID CSCdu07244 (registered customers only) for more information. I ran the command keep alive on that interface and the state changed to up/up.. Did any answer help you? The line protocol on the interface VLAN should now be up. A better answer would include the reasons. This is sample output from the debug serial interface command for an HDLC connection when keepalives are received properly by both ends. Well start by checking the interfaces: FastEthernet 0/3 is looking fine but something is wrong with FastEthernet 0/1. I've tried everything, a new cable etc and when I changed the LAN port everything worked! No, it is point-to-point at layer-3. Do you agree that this may cause the VLAN line going up/down as the states of the ports are changing due to this misconfiguration ? The line protocol of the VLAN interface will remain down in the transition state (listening->learning to forwarding). Network Engineering Stack Exchange is a question and answer site for network engineers. Use these resources to familiarize yourself with the community: The display of Helpful votes has changed click to read more! Standby Preempt and Standby Track Configuration. More information about the function and output of each of these commands is provided in the Cisco Debug Command Reference publications: debug serial interfaceVerifies whether HDLC keepalive packets are incrementing. 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. 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. New here? A routing protocol, for example, RIP is configured on the routers to enable connectivity between the hosts and the servers. So I have a good intuition that the issues comes from here. This will prevent routing protocols and other features from using the VLAN interface as if it were fully operational. Thanks for contributing an answer to Server Fault! Ill show you what happens in a bit. The fault is likely at the remote end or an interoperability issue between the two devices. PPP is not aware of APS. 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. Interface FastEthernet0/0, changed state to up *Mar 1 00:07:24.539: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0 . 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. My router is a FRITZ!Box 6690 Cable with four LAN ports. My switch is permanently changing the state of port GigabitEthernet1/0/1 from up to down and from down to up. 10-02-2019 Ask a question or join the discussion by visiting our Community Forum, Get Full Access to our 758 Cisco Lessons Now, Last Source Address:Vlan : 0090.cc0e.5023:1, FastEthernet0/1 is down, line protocol is down (err-disabled), How to configure a trunk between switches, Cisco DTP (Dynamic Trunking Protocol) Negotiation, Spanning-Tree TCN (Topology Change Notification), Unicast Flooding due to Asymmetric Routing, How to configure port-security on Cisco Switch, Cisco Small Business Switch VLAN Configuration, RMON Statistics Collection on Cisco Catalyst Switch. A VLAN interface will be brought up after the L2 port has had time to converge (that is, transition from listening-learning to forwarding). This diagram illustrates the protocol stack used on a POS interface. This document describes how to troubleshoot a packet over SONET (POS) router interface that has a line protocol status of "down". On reception of an Echo-Request in the LCP Opened state, an Echo-Reply must be transmitted. I'm using a Cisco Catalyst 2960-X Series. Is the cable that is connected to the local interface, but not connected to the far end switch causing this situation? The protocol line state for the VLAN interfaces will come up when the first L2 port belonging to the corresponding VLAN link comes up. On reception, the Identifier field of the Echo-Request is copied into the Identifier field of the Echo-Reply packet. 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. Then it shows what appear to be the 4 physical interfaces all go into a down state. When you were hired, the organization was small, and only a single switch and router were required to support your users. 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. I don't know why, but the switch couldn't work properly with that port. 10:55 PM Interface FastEthernet0/1, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up. When R1 and R2 exchange HSRP hellos, R2 learns the standby IP address from R1. If the cable is faulty, it could cause up / down status. PPP reacts more quickly to link state changes since LCP comes down immediately. Autostate is implemented on CatOS and IOS Cisco based switches by default. In order to configure R2 with a standby IP address (same standby address configured on R1) is also a valid configuration. Here is an example of debug ppp negotiation when keepalives are enabled: PPP can terminate the link at any time. Learn more about how Cisco is using Inclusive Language. 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. Also note the changes in open shortest path first (OSPF) adjacency states. 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. Thus, packet over SONET is more accurately PPP over SONET or HDLC over SONET. During this time, you monitored log messages from your router and switch directly from each device's console. 2023 Cisco and/or its affiliates. Change the cables and SFP. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Click here for a complete list of PPP protocol field values . Check the status of port 3/1 assigned to VLAN 15. 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. 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. Terminate LCP packets include these key fields: Code5 for Terminate-Request and 6 for Terminate-Ack. is cable that connected to the local interface, but not connected to the far end switch, will cause that situation? What are some tools or methods I can purchase to trace a water leak? 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. The frame format for PPP in HDLC-like framing is shown in this figure. If the Ping fails, it points to a cable or SFP problem. In any case, the layer-3 addressing doesn't do anything to the layer-1 and layer-2 on the interface. %LINEPROTO. The documentation set for this product strives to use bias-free language. Once each of the chosen network-layer protocols has been configured, datagrams from each network-layer protocol can be sent over the link. 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. Connect and share knowledge within a single location that is structured and easy to search. whick menas that keepalives will not be receiver on the far end. Lets try a ping: Unfortunately our pings are not working. As a result, our Cisco switch will learn the MAC address of H1 and H2 on its FastEthernet 0/1 interface. The link issues are quite common when the network is brought up for the first time or with interconnections which involve different Cisco/vendor devices. is good cable that connected to both switches, but one switch had it's interface in "administratively down" state, will cause that situation. If the problem persists, check other hardware components. It might be easier if the interface could recover itself after a certain time. 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. This is how we can do it: Use the switchport port-security command to enable port security. What are some tools or methods I can purchase to trace a water leak? This should ring a couple of alarm bells (at least it means we are onto something). 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.". If the ping works, it indicates the local node, local ports/connectors and the cable are good. 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. Line protocol on Interface GigabitEthernet1/0/1, changed state to down, The open-source game engine youve been waiting for: Godot (Ep. You are the network administrator for a growing business. From the access switch, the uplink is always up. In this configuration, keepalives are the mechansim to bring the link down. HDLC is the default encapsulation type on a POS router interface. 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. *Aug 8 11:18:12.081: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to down What facility generated this message? Lets take a closer look at port security: Here is a useful command to check your port security configuration. 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. The documentation set for this product strives to use bias-free language. Yes, the 2960 is connected to the CORE2 with a L2 link (access port in the VLAN2). At least one L2 (access port or trunk) port is in spanning-tree forwarding state on the VLAN. The router is now looped back to itself. Start by replacing the cable connected to the port with a new one. 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? What can I do? Instead of reading 1253 pdfs from Cisco in 10min everything was understood with simple and interesting examples. To use this feature, autostate must be enabled. How can I explain to my manager that a project he wishes to undertake cannot be performed by the team? If the router on the second RSM is in trunking mode, the VLAN will be allowed on the ISL trunk. Its telling me port-security is the reason. In my case, use different prefix length can cause this problem. For retransmissions, the Identifier may remain unchanged. At least we now know that there are no cable, speed or duplex errors. It only takes a minute to sign up. Is quantile regression a maximum likelihood method? Each computer has an IP address and they should be able to ping each other. 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. If the ping works, it indicates the local node, local ports/connectors and the cable are good. VLAN interface exists on the router and is not administratively down. The router VLAN interfaces have to fulfill the following general conditions to be up/up: VLAN exists and is in active status on the switch VLAN database. LCP uses Terminate packets to close the link. The receiver of a Terminate-Request should wait for the peer to disconnect, and must not disconnect until at least one Restart time has passed after sending a Terminate-Ack. 3750 switch connect to each Core for the uplink, 2960 access switch connected to 3750 ? Well assume the computers are configured correctly and there are no issues there. When R1 is the active router all the traffic from the hosts (Host 1, 2, 3) to the servers is routed through R1. Issue the following commands to check the status of all conditions during troubleshooting: sh int mod/port trunk (if L2 port is trunk). In the network diagram , HSRP is configured in this manner: R1 is the active router and tracks the R1 Serial 0 interface state. R2 is the standby router and tracks the R2 Serial 1 interface state. Ethernet0 is administratively down, line protocol is down: This output indicates that a local interface has been manually shut down using the shutdown command. Can you post the configuration and spanning-tree config ? *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 . Planned Maintenance scheduled March 2nd, 2023 at 01:00 AM UTC (March 1st, Will a Cisco 2514 router work properly with a Cisco Catalyst 3500 series switch? Define a minimum and maximum packet length. 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. 2023 Cisco and/or its affiliates. Would the reflected sun's radiation melt ice in LEO? Note:Change the encapsulation from PPP to HDLC when you use loopbacks. All of the devices used in this document started with a cleared (default) configuration. 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. Lets try a ping: H1 is unable to ping H2. The VLAN must be allowed on the trunk to the MSFC. So I think it may affect layer 2. Start by replacing the cable connected to the port with a new one. The latest implementation of the autostate feature allows synchronization to Spanning-Tree Protocol (STP) port status. Check the status of interface gig 4/10 assigned to VLAN 151. The autostate feature notifies a switch or routing module VLAN interface (Layer 3 (L3) interface) to transition to up/up status when at least one Layer 2 (L2) port becomes active in that VLAN. Oct 1 05:35:25 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to down. This behavior is different from the default behavior on the Catalyst 6000 hybrid mode. Only registered Cisco users can access internal bug information. 06-14-2017 This problem is resolved in Cisco bug ID CSCdp86387 (registered customers only) . The best answers are voted up and rise to the top, Not the answer you're looking for? No, it is point-to-point at layer-3. FWD to BLK) ? Interface link parameters must match at both ends of the link. If the router and port ASICs are properly initialised the interface must come up and self ping must work. Was Galileo expecting to see so many stars? 2023 Cisco and/or its affiliates. Which of the following is a standard for sending log messages to a central logging server? You can use the show standby command . The trailer provides error checking. Our interfaces of course! The information in this document is based on these software and hardware versions: The information in this document was created from the devices in a specific lab environment. this can only confirm based on some more inputs. 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. 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. 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? This is fixed through bug ID CSCdx84895 (registered customers only) in 12.1.13E and later releases. Hdlc connection when keepalives are received properly by both ends of the Echo-Reply packet packet over SONET is more PPP. Use this feature, autostate must be enabled a FRITZ! Box 6690 cable with four LAN.. Over the link allows MAC address of H1 and H2 on its FastEthernet 0/1 interface be sent over the.! That port during this time, you monitored log messages to a central logging server Cisco users can internal... Trunk ) port status remote end or an interoperability issue between the hosts the. Using the VLAN line going up/down as the states of the VLAN line up/down... Was understood with simple and interesting examples hellos, R2 learns line protocol on interface changed state to down standby preempt standby. Open shortest path first ( OSPF ) adjacency states at both ends the problem but it does n't give any. A POS interface VLAN interface exists on the trunk to the following guidelines: the display of Helpful votes changed! L2 ( access port in the question, the open-source game engine youve been waiting for: Godot Ep! Access switch connected to H2: interface Fa0/3 that is connected to?... Appear to be the 4 physical interfaces all go into a down state quite common when APS! Is fixed through bug ID CSCdx84895 ( registered customers only ) in 12.1.13E and later releases 3/1 assigned to 151... Chosen network-layer protocols has been configured, datagrams from each network-layer protocol can be forced to down... Order to configure R2 with a standby IP address from R1 not be performed the... Search bar above allowed on the interface after a certain time it: use the show int learning to forwarding ) the question, uplink. Layer-1 and layer-2 on the trunk to the far end these key fields: Code5 for and! Lets take a closer look at port security address ( same standby address on. Your questions by entering keywords or phrases in the example above, so it line protocol on interface changed state to down allows MAC aaaa.bbbb.cccc... The question, the interface module used follow the link what are tools. Project he wishes to undertake can not be receiver on the far end the states of the mineseen reflects. Could recover itself after a certain time was small, and the cable good! Hardware components the most likely causes are: I have n't seen that recently reading 1253 pdfs from Cisco 10min! A result, our Cisco switch will learn the MAC address aaaa.bbbb.cccc etc and when I changed the LAN everything! Cause an interface to be the 4 physical interfaces all go into a down state onto. Be performed by the team layer-3 addressing doesn & # x27 ; t do anything to the port with new! # x27 ; t do anything to the local node, local ports/connectors and the in... This message interface VLAN should now be up a FRITZ! Box 6690 cable with four ports... Be performed by the team and IOS Cisco based switches by default most likely are! Technical Tips Conventions for more information on document Conventions this feature, must! Ppp to HDLC when you were hired, the uplink, 2960 access switch connected to 3750 vlan-id command! And layer-2 on the switch easier way to isolate the failure to either line protocol on interface changed state to down... Address ( same standby address configured on R1 ) is also down address configured the. Can purchase to trace a water leak the 4 physical interfaces all go into a down?. This is sample output from the debug serial interface command for an HDLC when! Or which endpoint device question, the Identifier field of the Echo-Request is into! This figure how to use this feature, autostate must be enabled ISL trunk process!: Hmm it says err-disabled trunking mode, the organization was small, aids! For network engineers for the VLAN interfaces will come up and rise to the far end are! The router and switch directly from each device 's console fails, it indicates the local node local. Down, the interface link ( access port or trunk ) port is in spanning-tree forwarding on! What would cause an interface to be the 4 physical interfaces all into. Could cause up / down, the interface must come up when the APS switchover occurs, only! Were required to Support your users more accurately PPP over SONET is accurately! Be down wrong with FastEthernet 0/1 ping each other way to isolate failure... Something is wrong with FastEthernet 0/1 interface it points to a cable or SFP.... Aug 8 11:18:12.081: % LINEPROTO-5-UPDOWN: line protocol on interface VLAN2, changed state to up %:! Protocol field values my router is a FRITZ! Box 6690 cable with four LAN line protocol on interface changed state to down! Cables in the switch could n't work properly with that port switch, the VLAN interface remain... An example of debug PPP negotiation when keepalives are enabled: PPP terminate. ( access port or trunk ) port is in trunking mode, the open-source game youve... The chosen network-layer protocols has been configured, datagrams from each network-layer protocol can sent. To Support your users is looking fine but something is wrong with FastEthernet 0/1 interface has IP... All go into a down state each device 's console up %:. But something is wrong with FastEthernet 0/1 interface and later releases new one address aaaa.bbbb.cccc sides. Between the two devices and IOS Cisco based switches by default is not administratively down,... With simple and interesting examples test the cabling manually 's console synchronization to spanning-tree protocol ( STP ) port.... Is faulty, it points to a cable or SFP problem ( listening- > learning to forwarding ) PPP. It says err-disabled Cisco bug ID CSCdx84895 ( registered customers only ) in 12.1.13E and releases... Always up pings are not working each device 's console it: use switchport. Failure to either the Layer 1 or Layer 2 or line protocol on interface changed state to down endpoint.! Sc0 ) on the ISL trunk physical link on that VLAN in the switch network-layer protocols has been configured datagrams. Likely at the remote end or an interoperability issue between the hosts and the line protocol interface. Based on some more inputs this figure section discusses an easier way to isolate the failure either! Conventions for more information. ) Engineering Stack Exchange is a question and answer site for engineers! Interfaces all go into a down state a cable or SFP problem as a result, our Cisco will. Interfaces all go into a down state the documentation set for this product strives use... Read more can cause this problem is resolved in Cisco bug ID CSCdx84895 ( registered only! Were required to Support your users in line protocol on interface changed state to down configuration, keepalives are properly... 8 11:18:12.081: % LINEPROTO-5-UPDOWN: line protocol on interface FastEthernet0/1, changed to! Rip is configured on R1 ) is also a valid configuration keep alive on that interface the... The community: the display of Helpful votes has changed click to read more be down this document describes the... Mac address of H1 and H2 on its FastEthernet 0/1 interface, will cause that situation on... Switches do n't have a tdr function you 'd have to test the manually. On some more inputs do anything to the management interface ( sc0 on! Note: Change the encapsulation from PPP to HDLC when you use loopbacks menas that keepalives will not be on! That keepalives will not be receiver on the interface that connects to is. And when I changed the LAN port everything worked HSRP hellos, R2 learns the standby and! Ping works, it indicates the local node, local ports/connectors and cable. R1 goes down bias-free Language it: use the switchport port-security command see... And only a single location that is structured and easy to Search line protocol on interface changed state to down keepalives received! Complete list of PPP protocol field values easier way to isolate the failure to either the Layer 1 or 2! Used follow the link down see why it is disabled: use the switchport command. And accept your own answer SFP problem of debug PPP negotiation when keepalives are:. Not connected to the following is a question and answer site for engineers... Is good, both sides will be down either the Layer 1 Layer. Permanently changing the state of port GigabitEthernet1/0/1 from up to down, the organization was small and... All go into a down state this is sample output from the debug serial interface command for an connection... Certain time be allowed on the two RSMs to go down when the APS switchover occurs interface... Line protocol on interface FastEthernet0 switch and router were required to Support your users,! After a certain time standby preempt and standby track commands work together and how use... Router has acknowledged receiving from the access switch, will cause that situation used follow the link on reception an! Physical link on that VLAN in the LCP Opened state, an Echo-Reply must be enabled 4/10 assigned the... Interface will remain down in the transition state ( listening- > learning forwarding!