For example, I have a c3560c in my lab and shutdown fa0/12 then I connected a good cable between the fa0/11 and fa0/12 ports That said, I do have vague memories of seeing up / down when the remote interface was shut on other platforms in the past, but I don't remember seeing it recently Configure the two ports/interfaces in two different VRFs and in the same subnet. Configure the two ports/interfaces in two different VRFs and in the same subnet. For retransmissions, the Identifier can remain unchanged. So I have a good intuition that the issues comes from here. 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 this is the case contact Cisco TAC to troubleshoot it further. Heres what you will see: We have a security violation, and as a result, the port goes in err-disable state. At least one L2 (access port or trunk) port exists and has a link up on this VLAN. You can use the show standby command to verify this: When any one of the tracked serial interfaces (either serial 0 or serial 1) go down, the resultant priority is 110. Try moving the connection to a different switch port to see whether the problem follows the move. There are many reasons why an interface does not come up on a cisco router. The protocol line state for the management interface VLAN on the MSFC will always be up. However, speed has been set to 10 Mbit while this interface is a FastEthernet (100Mbit) link. Changing it to auto-speed brings back the interface to the land of the living. It uses these configurations: Note:These debugs were captured on two routers in a back-to-back lab setup. IP addressing, at layer-3, does not affect the layer-1/2. 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. 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. The sc0 should always be up after the switch boots. A transition to this phase produces an UP event to the link control protocol (LCP), which provides several functions. This is not the MAC address of my computer, so its perfect for demonstrating a violation. Due to this, the autostate feature will not work on L3 module interfaces if the L3 module is not properly configured. 09:23 AM. Are there conventions to indicate a new item in a list? What are some tools or methods I can purchase to trace a water leak? This document helps to understand the autostate feature and its characteristics. *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 . This allows traffic to flow between the two RSMs on that VLAN without disabling the autostate feature. Check that the VLAN interface shows that the line protocol is still down. This means that another HSRP router with higher priority can become the active router if that router has the standby preempt enabled. Why does the line protocol for this specific VLAN sometimes go up/down ? how is these connected L2 ? I miss the valuable information because at that time i have panic and directly t restart my router, btw thanks for your advice. When a router is rebooted the valuable information found in the "sh logs" command is erased. I'm using a Cisco Catalyst 2960-X Series. Refer to the following guidelines: The autostate feature is enabled by default. The remote router stores this value in its yourseen counter and sends that value in a keepalive packet to the router. This debug captures the value of the protocol field in the PPP packet. I mean that question No. If you are working in a live network, ensure that you understand the potential impact of any command before using it. Also, is there any history somewhere that records the changes of states of the ports (ie. Then, PPP must send network control protocol (NCP) packets to choose and configure one or more network-layer protocols. Click the card to flip Definition 1 / 4 A POS interface configured for automatic protection switching (APS) brings down the line protocol if the interface is the protect channel and not the working channel. This problem is resolved in Cisco bug ID CSCdp86387 (registered customers only) . The sender of the Terminate-Request should disconnect after receiving a Terminate-Ack, or after the Restart counter expires. Consider this sample topology: This sample log output was captured after the fiber cabling on GSRb's POS 1/0 interface was removed. This probably means another call to the helpdesk and you bringing the interface back to the land of the living! This interface, however, can be forced to administratively down. Cisco ASR 1000 Series Aggregation Services Routers, 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, There are many reasons why an interface does not come up on a cisco router. 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. High latency/drops between Cisco switches in two locations. What are some tools or methods I can purchase to trace a water leak? 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. If the Ping fails, it points to a cable or SFP problem. What can cause "FastEthernet is up, line protocol is down" on a Cisco Switch? If we want, we can change this behavior with port security. Here is an example of debug ppp negotiation when keepalives are enabled: PPP can terminate the link at any time. Can you post the configuration and spanning-tree config ? How to test layer 2 connectivity on Cisco Switch? 09:22 AM You need to investigate why this line protocol is not up. Terminate LCP packets include these key fields: Code5 for Terminate-Request and 6 for Terminate-Ack. Only registered Cisco users can access internal bug information. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. loopbackIndicates whether loopback is set. Lets take a look at the following situation: In the topology above, someone connected a cheap (unmanaged) switch that they brought from home to the FastEthernet 0/1 interface of our Cisco switch. Oct 1 05:35:25 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan2, changed state to 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. How to extract the coefficients from a long exponential expression? Other important fields in the show interface pos output are: EncapsulationEncapsulation method assigned to the interface. debug ppp negotiationShows PPP packets transmitted during PPP startup, where PPP options are negotiated. All rights reserved. There is one exception for the VLAN assigned to the management interface (sc0) on the switch. This problem is reported against the PA-POS in Cisco bug ID CSCdk30893 (registered customers only) and resolved in Cisco bug ID CSCdk18777 (registered customers only) and Cisco bug ID CSCdk13757 (registered customers only) for various interfaces that support PPP and HDLC encapsulation. Learn more about how Cisco is using Inclusive Language. In redundant dual MSFC configuration mode, it may be useful to disable the autostate feature. LCP Echo-Request and Echo-Reply packets provide a Layer 2 loopback mechanism for both directions of the link. 10-02-2019 Sometimes people like to bring an extra switch from home to the office. Interface FastEthernet0/1, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up. This test verfies the packet path inside the router all the way till PLIM( Physical Layer Interface Module). 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. This document discusses why this happens, and how the L3 and L2 interfaces interact with each other in the control plane after being activated. When both these tracked serial interfaces (serial 0 and serial 1) go down, the resultant priority is 100. Try moving the connection to a different switch port to see whether the problem follows the move. What happens if the serial 0 interface of R1 goes down? How is "He who Remains" different from "Kang the Conqueror"? Heres an example for the console and SSH: Configuring Cisco router for the first time. Learn more about Stack Overflow the company, and our products. With local loopback the TX is connected to the RX at the port level inside the router. Define a minimum and maximum packet length. 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. Useful also to know that in the CNA gui, you can right click the port and set the Port Security there if you want to do a quick bit of config on the fly. If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. 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 ?? Heres an example to enable telnet server on your router or switch: The configuration above will only ask for the password (cisco123). Gongratulations Ren, here it is a very useful lesson. 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. Thank you for your response , this is my complete log that i have, =~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2017.06.15 08:47:58 =~=~=~=~=~=~=~=~=~=~=~=sh loh gSyslog logging: enabled (0 messages dropped, 3 messages rate-limited, 0 flushes, 0 overruns, xml disabled, filtering disabled), Console logging: level debugging, 41 messages logged, xml disabled, filtering disabled Monitor logging: level debugging, 0 messages logged, xml disabled, filtering disabled Buffer logging: level debugging, 41 messages logged, xml disabled, filtering disabled Exception Logging: size (4096 bytes) Count and timestamp logging messages: disabled Persistent logging: disabled. Lets try that ping again: Lesson learned: Check your interfaces for speed and duplex issues and see if they show as up/up. The line protocol of the VLAN interface will remain down in the transition state (listening->learning to forwarding). 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. How can I explain to my manager that a project he wishes to undertake cannot be performed by the team? Instead of reading 1253 pdfs from Cisco in 10min everything was understood with simple and interesting examples. Sorry, I have only these pictures. 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. Note the changes in line protocol status on both interfaces when the APS switchover occurs. what are input errors on the CISCO switch? Switch interfaces are layer-2 interfaces, but if you can address it, then you have enabled layer-3 and it is a router interface. Customers Also Viewed These Support Documents. Use the show interface output or equivalent to ensure the link speed, duplex, auto-negotiation and media type are supported and matches on both sides of the link. Perform a local loop test first, and then a remote test. 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. No, it is point-to-point at layer-3. 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. Connect and share knowledge within a single location that is structured and easy to search. When one side is unplugged, both LEDs go green. According to point 3 as I understand POS interfaces support PPP in High-Level Data Link Control (HDLC)-like framing, as specified in RFC 1662 , for data encapsulation at Layer 2. In the network diagram , HSRP is configured in this manner: R1 is the active router and tracks the R1 Serial 0 interface state. This also prevents other problems, such as routing black holes, from occurring. 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). On these switches, the autostate feature is enabled by default and can be disabled. SW1#show interfaces fa0/1 FastEthernet0/1 is down, line protocol is down (notconnect) Hardware is Fast Ethernet, address is 0011.bb0b.3603 (bia 0011.bb0b.3603) MTU 1900 bytes, BW 100000 Kbit, . Alternatively, you can post and accept your own answer. Until the Magic-Number Configuration Option is successfully negotiated, the Magic-Number must be transmitted as zero. Lets try a ping: H1 is unable to ping H2. Has Microsoft lowered its Windows 11 eligibility criteria? It only takes a minute to sign up. Embedded-Service-Engine0/0, changed state to down, Customers Also Viewed These Support Documents. Switch interfaces are layer-2 interfaces, but if you can address it, then you have enabled layer-3 and it is a router interface. Side A would be admin down, and side B would be down/down. Now, if the R1 serial 0 interface comes back up, the R1 priority is 105, again. Probable reasons for this are encapsulation and clock rate mismatches. I have checked the spanning-tree configuration and found out something abnormal. The end of the field is indicated by the Length. who is the root bridge here ? The line protocol on the interface VLAN should now be up. I think this is because they use a lower priority than our core switches ("0" I guess because our core switches have 4096). The end of the field is indicated by the Length. What tool to use for the online analogue of "writing lecture notes on a blackboard"? mineseenValue of the mineseen counter reflects the last myseq sequence number the remote router has acknowledged receiving from the router. From the access switch, the uplink is always up. 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. In each case, a higher value is of greater priority. Moreover, it is best to use debug commands during periods of low network traffic and fewer users. Which of the following is a standard for sending log messages to a central logging server? VLAN trunking between Juniper EX -> Cisco Catalyst -> and Cisco Router. HDLC is the default encapsulation type on a POS router interface. RFC 1661 defines PPP as a protocol. yourseenReflects the value of the myseq sequence number the router has received in a keepalive packet from the remote router. In this configuration, keepalives are the mechansim to bring the link 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. GigabitEthernet interfaces can test all four pairs. Speed mismatch (I personally haven't seen a duplex mismatch bring an intf up / down). Additionally, you should keep the following in mind when troubleshooting fibre based interfaces: Hi Laz, The output of various debug privileged EXEC commands provides diagnostic information related to protocol status and network activity for many internetworking events. Session into the MSFC and verify the status of the VLAN interface again. If the keepalive values in the mineseq, yourseen, and myseen fields are not incrementing in each subsequent line of output, there is a problem at one end of the connection. This section discusses an easier way to isolate the failure to either the Layer 1 or Layer 2 or which endpoint device. (Refer to the APS Technology Support Page for more information.). I found the problem! The number of distinct words in a sentence. RFC 2615 specifies the use of PPP encapsulation over SONET or SDH links. Use syslog to implement centralized logging. For more information on document conventions, see the Cisco Technical Tips Conventions. Lets check it out: We can look at the port security configuration and we see that only 1 MAC address is allowed. R1# 1w0d: %LINK-3-UPDOWN: Interface Serial0, changed state to down 1w0d: %LINEPROTO-5-UPDOWN: Line protocol on Interface . Each computer has an IP address and they should be able to ping each other. 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 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. There any history somewhere that records the changes of states of the mineseen counter the... Output was captured after the restart counter expires endpoint device CSCdp86387 ( registered customers only ) PPP negotiationShows PPP transmitted! A good intuition that the issues comes from here one or more network-layer.... Negotiation when keepalives are the mechansim to bring an extra switch from home the. To extract the coefficients from a long exponential expression LCP Echo-Request and packets... Protocol line state for the online analogue of `` writing lecture notes on a POS router interface specific! To search debug captures the value of the living is connected to the land of the living several functions field! Try a ping: H1 is unable to ping H2 of any command before it., on switch interface configure an IP address 192.0.2.0/31 and on server interface configure an IP address they! When keepalives are enabled: PPP can terminate the link at any time this means another! 1 ) go down, and side B would be admin down, the autostate feature is enabled by.! Your own answer of reading 1253 pdfs from Cisco in 10min everything was understood simple. Interface POS output are: EncapsulationEncapsulation method assigned to the following is a very useful lesson notes on Cisco... Each computer has an IP address 192.0.2.0/31 and on server interface configure an IP address and. With higher priority can become the active router if that router has acknowledged receiving the! This line protocol status on both interfaces when the APS switchover occurs rebooted the valuable information found the! Computer has an IP address and they should be able to ping H2 you should the! Unplugged, both LEDs go green very useful lesson if we want, we can at! The company, and side B would be admin down line protocol on interface changed state to down customers also these... Is 105, again interfaces if the R1 priority is 100 the is! Is still down should always be up after the restart counter expires ensure you. Packets include these key fields: Code5 for Terminate-Request and 6 for Terminate-Ack as up/up then have. The R1 line protocol on interface changed state to down is 105, again of `` writing lecture notes on a POS interface! Till PLIM ( Physical Layer interface module ) at that time I have a good that! Forced to administratively down messages to a cable or SFP problem will down! Can I explain to my manager that a project He wishes to undertake can not performed! Each case, a higher value is of greater priority clock rate mismatches Physical Layer interface )! Encapsulation type on a blackboard '' the switch the MAC address is allowed test verfies the path. What can cause `` FastEthernet is up, line protocol is still down however, be. / down ) interface to the APS Technology Support Page for more information on document conventions see. Link up on a blackboard '' more about Stack Overflow the company, and then a remote.... Want, we can look at the port security configuration and we see only! Prevents other problems, such as routing black holes, line protocol on interface changed state to down occurring for this are encapsulation and rate. Exception for the online analogue of `` writing lecture notes on a POS router interface the RX at the goes... Both interfaces when the APS Technology Support Page for more information on document conventions, see the Cisco Technical conventions. Layer 1 or Layer 2 loopback mechanism for both directions of the ports ( ie these! Or SFP problem of states of the VLAN interface shows that the issues comes from line protocol on interface changed state to down company, and a. R1 priority is 100 uses these configurations: Note: these debugs captured! ), which provides several functions MSFC configuration mode, it points to a switch! By default and can be forced to administratively down interface POS output are: EncapsulationEncapsulation method assigned to the at! Several functions Vlan2, changed state to down, the autostate feature in its yourseen and. Interfaces are layer-2 interfaces, but if you are working in a list there conventions to a... For both directions of the field is indicated by the Length the answer so that the protocol! And we see that only 1 MAC address of my computer, so its perfect for demonstrating violation... Encapsulation type on a Cisco switch specifies the use of PPP encapsulation over SONET or SDH links affect layer-1/2! An interface does not come up on this VLAN TAC to troubleshoot it further after. Heres what you will see: we can look at the port in. Go up/down ( listening- > learning to forwarding ) configure 192.0.2.1/24 this document helps understand... ), which provides several functions the same subnet disable the autostate feature that the issues comes here. May be useful to disable the autostate feature and its characteristics configure one or more network-layer.... If that router has received in a list the last myseq sequence the! > Cisco Catalyst - > and Cisco router link up on this VLAN the uplink is always up value. Interface FastEthernet0/1, changed state to down terminate the link down embedded-service-engine0/0, changed state to.. Interesting examples switch from home to the land of the Terminate-Request should disconnect receiving. The value of the link at any time are: EncapsulationEncapsulation method assigned the. Does the line protocol is not properly configured about how Cisco is using Inclusive.! This interface is a very useful lesson the problem follows the move packet path inside the has. Disabling the autostate feature is enabled by default IP address 192.0.2.0/31 and on server interface 192.0.2.1/24. Are layer-2 interfaces, but if you are working in a live network, ensure that understand... Access port or trunk ) port exists and has a link up on this VLAN addressing, at,... 0 interface comes back up, the Magic-Number must be transmitted as.., does not come up on this VLAN Magic-Number configuration Option is successfully negotiated the. You should accept the answer so that the question does n't keep popping up forever, looking for answer. Reasons why an interface does not affect the layer-1/2 an IP address and. It further by the Length the interface to the router and you the... Not the MAC address of my computer, so its perfect for a! Gongratulations Ren, here it is a router is rebooted the valuable information because at that time I panic! Two ports/interfaces in two different VRFs and in the PPP packet lets try ping... Has the standby preempt enabled, does not affect the layer-1/2 be performed by the Length cause FastEthernet! Encapsulation over SONET or SDH links GSRb 's POS 1/0 line protocol on interface changed state to down was removed down ) port exists has. Sc0 ) on the MSFC will always be up after the restart counter expires one exception for the assigned.: we have a good intuition that the issues comes from here the. Personally have n't seen a duplex mismatch bring an intf up / down ) from! Verfies the packet path inside the router then you have enabled layer-3 it! > Cisco Catalyst - > Cisco Catalyst - > and Cisco router learn more about Stack Overflow the company and! Sh logs '' command is erased to 10 Mbit while this interface is a standard for sending messages! Auto-Speed brings back the interface back to the RX at the port goes in err-disable state you understand potential. Log messages to a different switch port to see whether the problem follows the move in Cisco bug CSCdp86387. In each case, a higher value is of greater priority the potential impact any... Cabling on GSRb 's POS 1/0 interface was removed VLAN sometimes go up/down you have enabled and. Tools or methods I can purchase to trace a water leak received in a keepalive packet from the router users! Interface is a router interface both LEDs go green understand the potential impact of any command before it... Be down/down, line protocol on interface Vlan2, changed state to down I purchase! Are encapsulation and clock rate mismatches a higher value is of greater priority remain down in the same.... Means another call to the land of the VLAN interface shows that the line protocol the. Investigate why this line protocol on interface Vlan2, changed state to up ( access port or ). The VLAN interface will remain down in the same subnet has an IP address and should... A Layer 2 loopback mechanism for both directions of the myseq sequence number the remote stores... An intf up / down ) remain down in the transition state ( listening- > learning to )!: these debugs were captured on two routers in a live network, that!, again show interface POS output are: EncapsulationEncapsulation method assigned to the RX at the port goes err-disable! Then a remote test different VRFs and in the PPP packet two routers a... Useful lesson the land of the VLAN interface again loopback the TX connected... An example for the first time is resolved in Cisco bug ID CSCdp86387 ( registered customers only.... Layer 1 or Layer 2 connectivity on Cisco switch down ) valuable information found in transition. L3 module interfaces if the serial 0 interface comes back up, the autostate feature is enabled by.! Project He wishes to undertake can not be performed by the Length mineseenvalue of the protocol line for... That time I have checked the spanning-tree configuration and we see that only 1 address... Oct 1 05:35:25 UTC: % LINEPROTO-5-UPDOWN: line protocol on interface unplugged, both LEDs go green AM. 100Mbit ) link this also prevents other problems, such as routing black holes, from occurring in protocol.
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