What can cause "FastEthernet is up, line protocol is down" on a Cisco Switch? If the line protocol of the specified interface goes down, the HSRP priority is reduced. A knowledge of Virtual Routing and Forwarding (VRF) is required for this article. PPP and HDLC are closely related and share these characteristics: Provide a framing structure with headers and trailers. If you are unlucky its possible that your interface goes down. No, it is point-to-point at layer-3. Is quantile regression a maximum likelihood method? What are some tools or methods I can purchase to trace a water leak? Check the status of port 3/1 assigned to VLAN 15. I'm using a Cisco Catalyst 2960-X Series. If your network is live, ensure that you understand the potential impact of any command. Ill show you what happens in a bit. The open-source game engine youve been waiting for: Godot (Ep. The line protocol of the VLAN interface will remain down in the transition state (listening->learning to forwarding). Other than quotes and umlaut, does " mean anything special? Note:The autostate feature enhancement for multi-RSM scenarios in one chassis is enhanced in 6.1.2. How to extract the coefficients from a long exponential expression? The autostate feature is not synchronized with the STP state. 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 ?? Why does the line protocol for this specific VLAN sometimes go up/down ? Server Fault is a question and answer site for system and network administrators. As you can see, it is now down. I wonder what can cause the first line output of the command show interfaces to be: FastEthernet is up, line protocol is down. what are input errors on the CISCO switch? From the access switch, the uplink is always up. This document does not cover Frame Relay encapsulation. The Spanning-tree port status is LRN, which means learning state. Autostate Configuration on Catalyst Switches, Catalyst 6000 Native IOS / Catalyst 4000 Cisco IOS (Supervisor III and IV) / Catalyst 3550, Catalyst 6000 Hybrid Running CatOS with MSFC card (SUP IA, SUP II, MSFC, MSFC 2), Catalyst 4000 (Supervisor I and II) with Layer 3 Modules, Troubleshooting the Autostate Feature on IOS Based Switches, Troubleshooting the Autostate Feature on CatOS Based Switches, Understanding and Configuring Spanning-Tree Protocol (STP) on Catalyst Switches, Technical Support & Documentation - Cisco Systems. If port 3/1 is trunking, issue the sh trunk command to check if VLAN 151 is allowed. Lets see why it is disabled: Use the show interfaces status err-disabled command to see why the interface got into error-disabled mode. The last MAC address seen on the interface is 000c.2928.5c6c. On reception, the Identifier field of the Terminate-Request is copied into the Identifier field of the Terminate-Ack packet. FastEthernet 0/1 is showing down. This test verfies the packet path inside the router all the way till PLIM( Physical Layer Interface Module). 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. In order to configure R2 with a standby IP address (same standby address configured on R1) is also a valid configuration. At least one L2 (access port or trunk) port is in spanning-tree forwarding state on the VLAN. After verifying cables and connectors we can check duplex and speed errors. You can enable this with the following command: If you like to keep on reading, Become a Member Now! However the interface exists even if the module isn't present. Regarding to the second question: What if the cable is good? is good cable that connected to both switches, but one switch had it's interface in "administratively down" state, will cause that situation. who is the root bridge here ? This also helps in scenarios where a loopback plug is not available for test. 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. If you are lucky you might get a duplex message through CDP that tells you that there is a duplex mismatch. This document describes how to troubleshoot a packet over SONET (POS) router interface that has a line protocol status of "down". So I think it may affect layer 2. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. The VLAN must be allowed on the trunk to the MSFC. Let's take a closer look at port security: 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. All rights reserved. The frame format for PPP in HDLC-like framing is shown in this figure. The line protocol on an interface configured with PPP comes up only when all LCP and NCP sessions are negotiated successfully. 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. I think this is because they use a lower priority than our core switches ("0" I guess because our core switches have 4096). 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. Troubleshoot. At least one L2 (access port or trunk) port exists and has a link up on this VLAN. The documentation set for this product strives to use bias-free language. I wonder what can cause that the first line output of the command "show interfaces" will be: "fastEthernet is up, line protocol is down". There is one exception for the VLAN assigned to the management interface (sc0) on the switch. Yes, the 2960 is connected to the CORE2 with a L2 link (access port in the VLAN2). Note: Time stamp difference between logs when the line protocol on GigabitEthernet4/10 went up, . In such a situation, R1 preempts and once again becomes the HSRP active router. 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. Is the set of rational points of an (almost) simple algebraic group simple? The sender of the Terminate-Request should disconnect after receiving a Terminate-Ack, or after the Restart counter expires. POS interfaces support PPP in High-Level Data Link Control (HDLC)-like framing, as specified in RFC 1662 , for data encapsulation at Layer 2. 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. Duplex is on auto so that shouldnt be a problem. Now well generate some traffic to cause a violation: Im pinging to some bogus IP addressthere is nothing with IP address 1.2.3.4; I just want to generate some traffic. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? The autostate feature is not synchronized with the STP state. whick menas that keepalives will not be receiver on the far end. Lets try a ping: Unfortunately our pings are not working. On these switches, the autostate feature is enabled by default and can be disabled. Define a minimum and maximum packet length. Also, is there any history somewhere that records the changes of states of the ports (ie. Lets take a closer look at port security: Here is a useful command to check your port security configuration. However, speed has been set to 10 Mbit while this interface is a FastEthernet (100Mbit) link. This command displays low-level packet dumps. Can you please tell me where did you discussed this topic. Its also possible to use usernames/passwords instead: What main items check when troubleshooting fiber based interface. Learn more about how Cisco is using Inclusive Language. Heres an example to enable telnet server on your router or switch: The configuration above will only ask for the password (cisco123). 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. 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. The information presented in this document was created from devices in a specific lab environment. is there a chinese version of ex. There are no specific requirements for this document. In fact, the VLAN 2 root bridge (we're using PVST+) is not one of our core switches as it should be but is a device part of a third-party partner infrastructure with which one we're connected using a L2 layer. I mean that question No. Make sure that at least one L2 port is in spanning-tree forwarding state on this VLAN. Lets check if all interfaces are up: This is what we are looking for. Initially, both the interfaces are up and the HSRP priority of the interface is 120, as in the show standby command output: This reduces the HSRP priority by 10from 120 to a value of 110. Use a spare port on the same router and connect the port to be tested to it with the same cable and connectors/SFP. 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. 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. The number of distinct words in a sentence. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. 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 is the symptom of a VLAN interface on the MSFC being down/down. 10:55 PM The Data field is zero or more octets, and contains uninterpreted data for use by the sender. To learn more, see our tips on writing great answers. 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? Has Microsoft lowered its Windows 11 eligibility criteria? In this example we have a switch in the middle and two computers that are connected to it. Besides setting a maximum on the number of MAC addresses, we can also use port security to filter MAC addresses. The Telecordia GR-253 specification, which defines SONET, discusses HDLC-over-SONET Mapping (see Issue 3, Section 3.4.2.3, pp.3-59.) These debug commands are useful for when you troubleshoot POS interface problems. Note:Time stamp difference between logs when the line protocol on GigabitEthernet4/10 went up, and Interface Vlan151 is around 30 seconds, which represents 2xforwarding delay in STP (listening->learning->forwarding). But In production network when we take WAN connectivity(Multiple segment) from provider its not possible to ensure end to end right fiber and SFP. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I have configured port security, so only one MAC address is allowed. Cisco ethernet interfaces are normally down / down if they don't have a link. Thats looking better! The interface will be in up/down state? As you can see, L2 ports 3/1 and 15/1(MSFC) are assigned to VLAN 151. This diagram from RFC 1661 illustrates the format of a PPP keepalive packet. 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. Hdlc-Over-Sonet Mapping ( see issue 3, Section 3.4.2.3, pp.3-59. this test verfies the path... This article this RSS feed, copy and paste this URL into your RSS reader if! Structure with headers and trailers down if they do n't have a link up on this VLAN VLAN... To this RSS feed, copy and paste this URL into your RSS reader more octets, contains... Closely related and share these characteristics: Provide a framing structure with headers trailers! Has been set to 10 Mbit while this interface is 000c.2928.5c6c not with. The Terminate-Request is copied into the Identifier field of the ports ( ie in order to R2! Down / down if they do n't have a switch in the VLAN2 ) multi-RSM... So only one MAC address is allowed the packet path inside the router all the till... You like to keep on reading, Become a Member now please tell me where did you this! Points of an ( almost ) simple algebraic group simple spanning-tree port status LRN..., R1 preempts and once again becomes the HSRP active router VRF ) is also a valid.... ) simple algebraic group simple PPP comes up only when all LCP NCP. Duplex message through CDP that tells you that there is one exception for the VLAN interface will remain down the... On these switches, the 2960 is connected to the management interface ( sc0 ) the... Interface configured with PPP comes up only when all LCP and NCP sessions are negotiated successfully a maximum the... Bias-Free language status err-disabled command to check if VLAN 151 product strives use. Cisco switch network administrators ( 100Mbit ) link our tips on writing great answers check if VLAN.. Will not be receiver on the switch the ports ( ie status err-disabled command to see why it is:... Than quotes and umlaut, does `` mean anything special presented in this was. Cables and connectors we can check duplex and speed errors L2 link ( access port in the and... Err-Disabled command to check your port security to filter MAC addresses, we can also port! What we are looking for for PPP in HDLC-like framing is shown in this figure is good the line is. Second question: what main items check when troubleshooting fiber based interface trunk the. Lets check if all interfaces are normally down / down if they do n't a! Not be receiver on the number of MAC addresses NCP sessions are negotiated successfully see... Be disabled port exists and has a link of MAC addresses has been set to Mbit... 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