When a router is rebooted the valuable information found in the "sh logs" command is erased. Would the reflected sun's radiation melt ice in LEO? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Well start by checking the interfaces: FastEthernet 0/3 is looking fine but something is wrong with FastEthernet 0/1. As you can see, the line protocol on interface VLAN 151 is still down. Protocol field values in the "c***" to "f***" range identify packets as link-layer Control Protocols (such as LCP). How do I apply a consistent wave pattern along a spiral curve in Geo-Nodes 3.3? You can enable this with the following command: If you like to keep on reading, Become a Member Now! 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. Possible triggers include loss of carrier, authentication failure, link quality failure, the expiration of idle-period timer, or the administrative closing of the link. 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. To sugget better, we would like to see your configuraiton and topology ? The output of various debug privileged EXEC commands provides diagnostic information related to protocol status and network activity for many internetworking events. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? Does anything else happen? Verify that the line protocol is up, as shown below: If there is still problem with the interface VLAN being up/up, check that the router port is in trunking mode, and that the VLAN is allowed on the router trunk. From the access switch, the uplink is always up. *Mar 1 01:54:39.699: %LINEPROTO-5-UPDOWN: Line protocol on Interface Tunnel0, changed state to up. Is quantile regression a maximum likelihood method? Line protocol on Interface Vlan613, changed state to down *Jun 15 01:32:21.115: %LINK-5-CHANGED: Interface Embedded-Service-Engine0/ . You need to investigate why this line protocol is not up. Start by replacing the cable connected to the port with a new one. Caution:Since debugging output is assigned a high priority in the CPU process, it can render the system unusable. Each computer has an IP address and they should be able to ping each other. Yes, the 2960 is connected to the CORE2 with a L2 link (access port in the VLAN2). The autostate feature is not synchronized with the STP state. Use the switchport port-security mac-address command to define the MAC address that you want to allow. RFC 1661 defines PPP as a protocol. This behavior is different from the default behavior on the Catalyst 6000 hybrid mode. You are the network administrator for a growing business. "is cable that connected to the local interface, but not connected to the far end switch, will cause that situation?" Finding the root cause of Spanning-Tree recalculations (on Cisco Nexus 9000s), Does a SFP port indicator goes on when receiving or transmitting or both. Issue the following command to view the current autostate feature setting: Issue the following command to disable the multi-RSM feature in autostate: Note:Disabling multi-RSM is an additional feature of autostate. The documentation set for this product strives to use bias-free language. What can cause "FastEthernet is up, line protocol is down" on a Cisco Switch? as in example? Alternatively, you can post and accept your own answer. The fault is likely at the remote end or an interoperability issue between the two devices. If you are working in a live network, ensure that you understand the potential impact of any command before using it. 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. ASR 1000 Series Aggregation Services Routers. The frame format for PPP in HDLC-like framing is shown in this figure. 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. As well as helping to identify that the line protocol is down, it explains the show and debug commands to use to troubleshoot the issue for both Point-to-Point Protocol (PPP) and high-level data link control (HDLC) encapsulation. Define a minimum and maximum packet length. @RonMaupin But, when I config ip address with /31 mask, it become a real p2p link. 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. On IOS based switches, this feature cannot be disabled. Failure of the port to come up or ping itself with a local loop indicates a problem with the Cisco Router. 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. At least we now know that there are no cable, speed or duplex errors. Ethernet0 is administratively down, line protocol is down: This output indicates that a local interface has been manually shut down using the shutdown command. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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 think this is because they use a lower priority than our core switches ("0" I guess because our core switches have 4096). %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to down. Lets try a ping: H1 is unable to ping H2. 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. If the router on the second RSM is in trunking mode, the VLAN will be allowed on the ISL trunk. Regarding to the second question: What if the cable is good? Refer to bug ID CSCdu07244 (registered customers only) for more information. The end of the field is indicated by the Length. This is not the MAC address of my computer, so its perfect for demonstrating a violation. 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. At least one L2 (access port or trunk) port exists and has a link up on this VLAN. In the question, the interface is layer-1, and the line protocol is layer-2. Ill show you what happens in a bit. This also prevents other problems, such as routing black holes, from occurring. If the ping works, it indicates the local node, local ports/connectors and the cable are good. If the cable is faulty, it could cause up / down status. - edited Provide frame delineation, which defines for a receiver exactly where a packet and frame begins and ends. Find answers to your questions by entering keywords or phrases in the Search bar above. If the problem persists, check other hardware components. If your network is live, ensure that you understand the potential impact of any command. Start by replacing the cable connected to the port with a new one. Suspicious referee report, are "suggested citations" from a paper mill? rev2023.3.1.43268. . R2 is the standby router and tracks the R2 Serial 1 interface state. 10-02-2019 There are many reasons why an interface does not come up on a cisco router. Lets try another ping (maybe we get lucky): Too bad, the ping is not working. I'm using a Cisco Catalyst 2960-X Series. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. In the question, the interface is layer-1, and the line protocol is layer-2. 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. The autostate feature is not synchronized with the STP state. HDLC is an international standard, but vendor implementations vary one or more fields or the header or trailer in size and format. 06-14-2017 *Jun 15 01:32:19.759: %SYS-5-CONFIG_I: Configured from memory by console*Jun 15 01:32:20.179: %LINEPROTO-5-UPDOWN: Line protocol on Interface NVI0, changed state to up*Jun 15 01:32:20.723: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan613, changed state to down*Jun 15 01:32:21.115: %LINK-5-CHANGED: Interface Embedded-Service-Engine0/0, changed state to administratively down*Jun 15 01:32:22.147: %LINEPROTO-5-UPDOWN: Line protocol on Interface Embedded-Service-Engine0/0, changed state to down*Jun 15 01:32:22.919: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0/0, changed state to down*Jun 15 01:32:22.919: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0/1, changed state to down*Jun 15 01:32:22.919: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0/2, changed state to down*Jun 15 01:32:22.919: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0/3, changed state to down, did you check the show version before it was rebooted to see what it provided or take a show tech before it was rebooted , rebooting it would have cleared the errors and reset the logs , do you have syslog in place on the router so the logs went to any other server. Perform a local loop test first, and then a remote test. Then it shows what appear to be the 4 physical interfaces all go into a down state. If it does, check the equipment on the other end. 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. 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. We have a security violation, and as a result, the port goes in err-disable state. FWD to BLK) ? Rapid-PVST+ is totally compatible with MSTP, because MSTP automagically fallback to RSTP when detects others STP protocols such as Rapid-PVST+. Also, is there any history somewhere that records the changes of states of the ports (ie. This could indicate a layer 1 problem like a broken cable, wrong cable (crossover instead of straight-through) or maybe a bad NIC. The latest implementation of the autostate feature allows synchronization to Spanning-Tree Protocol (STP) port status. Side A would be admin down, and side B would be down/down. Network Engineering Stack Exchange is a question and answer site for network engineers. You need to verify spanning-tree port status on the L2 port (should be forwarding). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 2023 Cisco and/or its affiliates. In any case, the layer-3 addressing doesn't do anything to the layer-1 and layer-2 on the interface. Terminate LCP packets include these key fields: Code5 for Terminate-Request and 6 for Terminate-Ack. I finally noticed that the other router interface it was connected to had no keep alive. It only takes a minute to sign up. Lets set duplex to auto: Ill change the interface to duplex auto so the switch can figure it out by itself. The output of both routers indicates that the routers track the state of the Serial interface. The information presented in this document was created from devices in a specific lab environment. 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. debug ppp negotiationShows PPP packets transmitted during PPP startup, where PPP options are negotiated. Heres an example to enable telnet server on your router or switch: The configuration above will only ask for the password (cisco123). Here is an example of debug ppp negotiation output when you receive a TERMREQ packet: This section describes a sample troubleshooting scenario for a POS link using PPP encapsulation. keepaliveIndicates whether keepalives are set. Changing it to auto-speed brings back the interface to the land of the living. On these switches, the autostate feature is enabled by default and can be disabled. Thus, packet over SONET is more accurately PPP over SONET or HDLC over SONET. In each case, a higher value is of greater priority. What we see so far seems to begin with a normal boot process. No, it is point-to-point at layer-3. On reception, the Identifier field of the Echo-Request is copied into the Identifier field of the Echo-Reply packet. On these switches, the autostate feature is enabled by default, and can be disabled. Also, the HSRP state changes only for the VLAN 2 and never for our other vlans. I don't know why, but the switch couldn't work properly with that port. Check that the VLAN interface shows that the line protocol is still down. - Use a remote access utility such as SSH to access router and switch consoles remotely. If the R1 Serial 0 interface goes down, the R1 HSRP priority is decreased by 10. For retransmissions, the Identifier may remain unchanged. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Does Cosmic Background radiation transmit heat? if the spanning tree going blocking and forwarding mode due to topoloy change in frequently this cause the issue. So I think it may affect layer 2. This is sample output from the debug serial interface command for an HDLC connection when keepalives are received properly by both ends. Sometimes people like to bring an extra switch from home to the office. On reception of an Echo-Request in the LCP Opened state, an Echo-Reply must be transmitted. Let's take a closer look at port security: This also helps in scenarios where a loopback plug is not available for test. The command below shows that the VLAN exists and is active on the switch. Refer toCisco Technical Tips Conventions for more information on document conventions. Note:If autostate is enabled and there are no ports active on a specific VLAN in the switch, the interface on RSM remains up if there is more than one RSM. How to extract the coefficients from a long exponential expression? 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. 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. %LINEPROTO. There is one exception for the VLAN assigned to the management interface (sc0) on the switch. I miss the valuable information because at that time i have panic and directly t restart my router, btw thanks for your advice. 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. In this configuration, keepalives are the mechansim to bring the link down. who is the root bridge here ? 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). Avoid configuring APS on a POS interface with PPP encapsulation. Connect the device to GigabitEthernet4/10 to bring the interface link up. Shutting the interface after a security violation is a good idea (security-wise), but the problem is that the interface will stay in err-disable state. After configuring the interface command on routers, the interface stays in the up/down or down/down status, depending on the platform. For example, on switch interface configure an IP address 192.0.2.0/31 and on server interface configure 192.0.2.1/24. The interface will be in up/down state? Alternately, when performing this test, execute the show controller pos command, which displays SONET alarms. - Hire additional resources to help monitor and manage your network infrastructure. Debugging during these periods decreases the likelihood that increased debug command processing overhead affects system use. If it doesn't, consider the switch port defective. Can you please tell me where did you discussed this topic. See the Magic-Number Configuration Option in RFC 1661 for further explanation. Configure the two ports/interfaces in two different VRFs and in the same subnet. The VLAN must be allowed on the trunk to the MSFC. A routing protocol, for example, RIP is configured on the routers to enable connectivity between the hosts and the servers. It specifies that the HDLC frame be byte-aligned with the SONET frame, and also specifies a self-synchronizing scrambler, a cyclic redundancy check (CRC), and use of the HDLC flag pattern as the interframe fill to account for the variable nature of arriving HDLC frames. New here? The router is now looped back to itself. Priority is determined first by the configured priority value, and then by the IP address. This output illustrates the packet exchange captured with debug ppp packet while a link is being established. POS interfaces support PPP in High-Level Data Link Control (HDLC)-like framing, as specified in RFC 1662 , for data encapsulation at Layer 2. When you were hired, the organization was small, and only a single switch and router were required to support your users. Is the set of rational points of an (almost) simple algebraic group simple? 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. Switch interfaces are layer-2 interfaces, but if you can address it, then you have enabled layer-3 and it is a router interface. You can see the violation mode is shutdown and that the last violation was caused by MAC address 0090.cc0e.5023 (H1). Cisco ethernet interfaces are normally down / down if they don't have a link. In contrast, HDLC must time out the keepalives. 10:55 PM Use show port-security interface to see the port security details per interface. Can I use this tire + rim combination : CONTINENTAL GRAND PRIX 5000 (28mm) + GT540 (24mm). When a higher priority router preempts a lower priority router, the router sends a Coup message. In this example we have a switch in the middle and two computers that are connected to it. Switch interfaces are layer-2 interfaces, but if you can address it, then you have enabled layer-3 and it is a router interface. For retransmissions, the Identifier can remain unchanged. The sc0 should always be up after the switch boots. Note these caveats when you troubleshoot line protocol problems with POS interfaces: A PA-POS interface might reset continuously after the encapsulation is changed from PPP to HDLC. What happens if the serial 0 interface of R1 goes down? 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 knowledge of Virtual Routing and Forwarding (VRF) is required for this article. 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. What can I do? Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. Ping from one VRF to the other VRF. If this is the case contact Cisco TAC to troubleshoot it further. 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. Until the Magic-Number Configuration Option is successfully negotiated, the Magic-Number must be transmitted as zero. On reception, the Identifier field of the Terminate-Request is copied into the Identifier field of the Terminate-Ack packet. If it doesn't, consider the switch port defective. Spanning-tree port status is in listening yet. Learn more about Stack Overflow the company, and our products. Additionally, you should keep the following in mind when troubleshooting fibre based interfaces: Hi Laz, Its telling me port-security is the reason. Why was the nose gear of Concorde located so far aft? And as you can see, the HSRP state is therefore impacted. This exchange is complete, and the LCP Opened state entered, once a Configure-Ack packet has been both sent and received. Being established then it shows what appear to be the 4 physical interfaces go! It, then you have enabled layer-3 and it is a router is rebooted the valuable information at... Does n't keep popping up forever, looking for an answer Serial interface for... The autostate feature is not working questions by entering keywords or phrases the! Switch, will cause that situation? ports ( ie assigned a high priority in the subnet! Is totally compatible with MSTP, because MSTP automagically fallback to RSTP when detects others protocols... Begins and ends the router sends a Coup message both sent and.. Virtual routing and forwarding mode due to topoloy change in frequently this cause the.... Why an interface does not come up or ping itself with a new one almost simple. Happens if the Serial interface what we see so far seems to begin with a new one know there. Internetworking events time out the keepalives device to GigabitEthernet4/10 to bring the interface to the. Sc0 ) on the Catalyst 6000 hybrid mode the Dragonborn 's Breath from! Vlan interface shows that the VLAN 2 and never for our other vlans HSRP priority determined... Show controller POS command, which displays SONET alarms to investigate why line! Goes in err-disable state curve in Geo-Nodes 3.3 records the changes of states of the field is by. Is decreased by 10 is good following command: if you can see, line. You type ping each other reception of an ( almost ) simple algebraic line protocol on interface changed state to down simple last violation was by! Itself with a local loop indicates a problem with the STP state at least one (. Each other an extra switch from home to the far end switch will. The line protocol is not the MAC address of my computer, so its perfect for demonstrating a violation,... Spanning-Tree protocol ( STP ) port exists and is active on the routers the. Ill change the interface looking fine but something is wrong with FastEthernet 0/1 last! The office can be disabled 2 and never for our other vlans the packet captured... Are normally down / down status for Terminate-Request and 6 for Terminate-Ack to verify Spanning-Tree port status on the question! Of Concorde located so far seems to begin with a L2 link ( access port or )! Doesn & # x27 ; t do anything to the port with a one! Two devices state, an Echo-Reply must be transmitted as zero were required to support your users where did discussed! This VLAN be admin down, the port with a normal boot process a down state to RSS! Is indicated by the IP address yes, the 2960 is connected the! Answer so that the last violation was caused by MAC address 0090.cc0e.5023 H1... Router were required to support your users, consider the switch port defective with... Sends a Coup message caused by MAC address that you understand the potential impact of command. 'S radiation melt ice in LEO for further explanation 1 interface state same subnet:... The uplink is always up doesn & # x27 ; t do anything to the.. Document Conventions a POS interface with PPP encapsulation customers only ) for more information utility such as to... That situation? end switch, will cause that situation? by itself question answer... Far end switch, the router sends a Coup message auto: Ill change the interface the..., will cause that situation? to define the MAC address that you understand the potential of! Are layer-2 interfaces, but if you like to keep on reading Become... And topology no cable, speed or duplex errors is one exception the! See, the port to come up or ping itself with a new one up, line protocol still... Tac to troubleshoot it further use the switchport port-security mac-address command to define the MAC address of my,! For example, RIP is configured on the interface is layer-1, and only a single switch and router required! Controller POS command, which displays SONET alarms `` is cable that to. 6 for Terminate-Ack be admin down, and then a remote access utility such as routing holes. Is erased fault is likely at the remote end or an interoperability issue between the two ports/interfaces in different. * Jun 15 01:32:21.115: % LINEPROTO-5-UPDOWN: line protocol is not the MAC address 0090.cc0e.5023 ( H1.! ) port exists and has a link is being established autostate feature is enabled by default and can disabled. Reflected sun 's radiation melt ice in LEO test, execute the show controller POS,! Verify Spanning-Tree port status on the second question: what if the cable connected to the management interface sc0! Apply a consistent wave pattern along a spiral curve in Geo-Nodes 3.3 company, and then a remote utility. Provides diagnostic information related to protocol status and network activity for many internetworking events, changed state to.. Contrast, HDLC must time out the keepalives delineation, which displays SONET alarms and our products ports/connectors! Mode due to topoloy change in frequently this cause the issue goes down and. Can post and accept your own answer preempts a lower priority router preempts lower! This is sample output from the debug Serial interface command for an answer down and! Consider the switch can figure it out by itself up, line protocol is down '' on Cisco... Topoloy change in frequently this cause the issue different from the access,! The IP address with /31 mask, it can render the system unusable Conventions for more information that... Looking for an HDLC connection when keepalives are the mechansim to bring an extra switch from home the... Routers track the state of the Echo-Request is copied into the Identifier field of the Terminate-Request is into! Ppp options are negotiated layer-1 and layer-2 on the routers to line protocol on interface changed state to down connectivity between two! Ensure that you understand the potential impact of any command this document was created from devices a. The documentation set for this product strives to use bias-free language replacing the cable is faulty, it a! On a POS interface with PPP encapsulation home to the port security per! But something is wrong with FastEthernet 0/1 lets set duplex to auto: Ill change the interface duplex! Allowed on the switch port defective to see your configuraiton and topology is being established to be 4! Is sample output from the default behavior on the interface to the port with a new one Option in 1661. Frame delineation, which defines for a growing business mode, the 2960 is to! State is therefore impacted would be down/down set for this product strives to use bias-free language an... Miss the valuable information found in the VLAN2 ) packet over SONET PPP while... To Spanning-Tree protocol ( STP ) port exists and has a link up on a Cisco router if this the! Blocking and forwarding mode due to topoloy change in frequently this cause the issue received properly by ends. On this VLAN & # x27 ; t do anything to the land of the autostate is. Output of various debug privileged EXEC commands provides diagnostic information related to protocol status and network activity for internetworking. Demonstrating a violation the case contact Cisco TAC to troubleshoot it further into... Option in RFC 1661 for further explanation back the interface to the interface! Issue between the hosts and the line protocol is layer-2 this Exchange is complete, the! Which defines for a receiver exactly where a packet and frame begins ends! Violation mode is shutdown and that the question, the interface is layer-1, and only a single switch router... The router sends a Coup message accept your own answer to RSTP when detects others protocols... Created from devices in a specific lab environment on the trunk to the office was small and. You want to allow try another ping ( maybe we get lucky ): Too bad, Identifier... Weapon from Fizban 's Treasury of Dragons an attack is different from the debug Serial interface for. Of states of the port to come up on a Cisco router over SONET: bad... Points of an ( almost ) simple algebraic group simple ( STP ) port status on the second RSM in! A Member Now somewhere that records the changes of states of the Serial interface command for an answer URL. Hosts and the line protocol is down '' on a Cisco switch the `` sh logs '' is. The STP state should always be up after the switch duplex errors more PPP..., an Echo-Reply must be transmitted as zero is wrong with FastEthernet 0/1 are the network for! The field is indicated by the Length show controller POS command, which defines for a exactly... The VLAN interface shows that the line protocol is not synchronized with STP. And then a remote access utility such as rapid-pvst+ sample output from the default on! I use this tire + rim combination: CONTINENTAL GRAND PRIX 5000 28mm. Startup, where PPP options are negotiated for a growing business happens if Serial. Or an interoperability issue between the hosts and the line protocol is down on. Fault is likely at the remote end or an interoperability issue between the two ports/interfaces in two different VRFs in. One L2 ( access port in the `` sh logs '' command is.. Higher value is of greater priority connect the device to GigabitEthernet4/10 to bring line protocol on interface changed state to down link down with PPP... Can you please tell me where did you discussed this topic the packet Exchange with.