BIG-IP Advanced Routing

Transcription

1 BIG-IP Advanced Routing Troubleshooting Guide Version 7.5.1

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3 Publication Date This document was published on June 25, Legal Notices Copyright Copyright , F5 Networks, Inc. All rights reserved. F5 Networks, Inc. (F5) believes the information it furnishes to be accurate and reliable. However, F5 assumes no responsibility for the use of this information, nor any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent, copyright, or other intellectual property right of F5 except as specifically described by applicable user licenses. F5 reserves the right to change specifications at any time without notice. Trademarks AAM, Access Policy Manager, Advanced Client Authentication, Advanced Firewall Manager, Advanced Routing, AFM, Alive With F5, APM, Application Acceleration Manager, Application Security Manager, ARX, AskF5, ASM, BIG-IP, BIG-IQ, Cloud Extender, CloudFucious, Cloud Manager, Clustered Multiprocessing, CMP, COHESION, Data Manager, DevCentral, DevCentral [DESIGN], DNS Express, DSC, DSI, Edge Client, Edge Gateway, Edge Portal, ELEVATE, EM, Enterprise Manager, ENGAGE, F5, F5 [DESIGN], F5 Certified [DESIGN], F5 Networks, Fast Application Proxy, Fast Cache, FirePass, Global Traffic Manager, GTM, GUARDIAN, iapps, IBR, Intelligent Browser Referencing, Intelligent Compression, IPv6 Gateway, icontrol, ihealth, iquery, irules, irules OnDemand, isession, L7 Rate Shaping, LC, Link Controller, Local Traffic Manager, LTM, LineRate, LineRate Systems [DESIGN], LROS, Message Security Manager, MSM, OneConnect, Packet Velocity, PEM, Policy Enforcement Manager, Protocol Security Manager, PSM, Real Traffic Policy Builder, ScaleN, Signalling Delivery Controller, SDC, SSL Acceleration, StrongBox, SuperVIP, SYN Check, TCP Express, TDR, TMOS, Traffic Management Operating System, Traffix Systems, Traffix Systems (DESIGN), Transparent Data Reduction, UNITY, VAULT, VIPRION, vcmp, VE F5 [DESIGN], Virtual Clustered Multiprocessing, WA, WAN Optimization Manager, WebAccelerator, WOM, and ZoneRunner, are trademarks or service marks of F5 Networks, Inc., in the U.S. and other countries, and may not be used without F5's express written consent. All other product and company names herein may be trademarks of their respective owners. A portion of this reference guide is copyrighted by IP Infusion, Inc. ZebOS is a registered trademark, and IP Infusion and the ipinfusion logo are trademarks of IP Infusion. All other trademarks are trademarks of their respective companies. This documentation is subject to change without notice. The software described in this document and this documentation are furnished under a license agreement or nondisclosure agreement. The software and documentation may be used or copied only in accordance with the terms of the applicable agreement. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or any means electronic or mechanical, including photocopying and recording for any purpose other than the purchaser's internal use without the written permission of IP Infusion Inc. F5 Networks, Inc. (F5) believes the information it furnishes to be accurate and reliable. However, F5 assumes no responsibility for the use of this information, nor any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent, copyright, or other intellectual property right of F5 except as specifically described by applicable user licenses. F5 reserves the right to change specifications at any time without notice. All other product and company names herein may be trademarks of their respective owners. i

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5 Table of Contents CHAPTER 1 Introduction Useful System Commands and Utilities CHAPTER 2 Debugging and Logging Debugging Logging to stdout (terminal) Logging information to a file or syslog Turning off debugging CHAPTER 3 Troubleshooting BGP No BGP Adjacency Useful Show Commands show ip bgp show ip bgp summary show ip bgp neighbors CHAPTER 4 Troubleshooting OSPF No OSPF Adjacency Useful Show Commands show ip ospf interface show ip ospf neighbor show ip ospf database CHAPTER 5 Troubleshooting RIP No RIP Adjacency Useful Show Commands show ip rip interface show ip rip database CHAPTER 6 Troubleshooting LDP LDP Session is not UP CHAPTER 7 Troubleshooting VRRP Incorrect VRRP States CHAPTER 8 Troubleshooting PIM-SM No PIM adjacency No BSR and RP information RP not advertised in the BSR Troubleshooting Example Useful Show Commands show ip pim sparse-mode mroute show ip pim sparse-mode interface iii

6 Table of Contents CHAPTER 9 Troubleshooting BGP No BGP Adjacency Useful Show Commands show bgp ipv show bgp ipv6 summary CHAPTER 10 Troubleshooting OSPFv No OSPF Adjacency Useful Show Commands show ipv6 ospf database link [adv-router] show ipv6 ospf database intra-prefix [adv-router] CHAPTER 11 Troubleshooting RIPng No RIPng Adjacency CHAPTER 12 Route Selection in NSM How Does NSM Add Routes How does NSM Delete Routes Show Commands show ip route show ip route database CHAPTER 13 Miscellaneous Issues Kernel does not notify the NSM about updating the MTU/metric OSPF adjacency lost (System Clock) Remote Devices are unreachable Index Index - 1 iv

7 CHAPTER 1 Introduction This guide is intended for all network administrators and application developers who install and configure ZebOS IP routing software. It requires that the user has a broad understanding of networking principles and network configuration. Use this information with the other F5 Networks technical information available with the software. This guide contains tips for troubleshooting basic issues faced during installation, configuration and management of ZebOS IP routing software. Useful System Commands and Utilities These Unix Commands and GNU Utilities are useful in troubleshooting. Unix commands might have different syntax when used on different platforms. Note: Use man <command> to get detailed information about any Unix command. id ifconfig ls man netstat ping This id utility displays the system identifications (ID) for a specified user. The system IDs identify users and user groups to the system. This utility displays the user name, user ID, as well as the group name and group ID of the user. In addition, id also displays the effective user and group IDs (euid). Install ZebOS as a root user. Use this command to verify that you are the root user. Configures a network interface. It is used at boot time to set up interfaces or for debugging purposes. Use the -a flag with this command to instruct ifconfig to display information about all interfaces on the system. You can use this utility to configure the loopback address: ifconfig lo Lists the contents of the current working directory. It provides access to online manual pages and information on how to run a specified command. For example, to learn more about rm (file-removal) command type: man rm Use option -k with the man command if you do not know which command to look for. This option directs man to search for manual pages containing the specified keyword. If the information is more than one screenful of text, the man command shows the first screen and prompts you with More at the bottom of the screen. Hit the spacebar when you are ready for the next screenful. Type q to quit. Displays different network related data structures. You can use various options to get different outputs, such as -r option displays routing tables. The -n option used along with the -r option displays network addresses as numbers. It is used to see if a system is operating and also to see if network connections are intact. It uses the Internet Control Message Protocol (ICMP) Echo function (detailed in RFC 792). A small packet is sent through the network to a particular IP address. The sender then listens for a return packet, if connections are good and the target system is up, a good return packet is received. 1

8 Introduction ping6 ssh su telnet traceroute traceroute6 uname useradd userdel which It uses the ICMPv6 Echo function (detailed in RFC 2463) to report errors encountered in processing packets and to perform diagnostics. This utility is available on Linux and FreeBSD systems. On a Solaris system the ping utility has both IPv4 and IPv6 capability. Use Secure Shell (SSH) to log into another computer over a network, to execute commands from a remote machine, and to move files from one machine to another. SSH can be used in place of telnet, rlogin, rsh etc. It provides authentication and secure communications over insecure channels. The su command changes the user ID to those of the root user or to any other specified user. It is a User Interface to the TELNET protocol. It runs on your computer and connects it to a server on the network. You can then enter commands through the Telnet program and they are executed as if you were entering them directly on the server console. This enables you to control the server and communicate with other systems on the network. Traces a packet from your system to a host showing the number of hops the packet requires to reach the host and how long each hop takes. Displays information about the route taken by the IPv6 packets to reach the destination. This utility is available on Linux and FreeBSD systems. On a Solaris system the traceroute utility has IPv4 and IPv6 capability. Displays information about the name and version of the current Operating System. Creates a new User or updates default User information. This utility works on Linux and Solaris systems. On a FreeBSD system use the pw utility to create a new user. Deletes a User Account and its related files. This utility works on Linux and Solaris systems. On a FreeBSD system use the pw utility to delete an User Account. Shows the complete path of the given command. If the command is missing in the path, a message is displayed stating that the command is missing. For example, using which telnet confirms if telnet is installed on your system and gives the path to reach it. 2

9 CHAPTER 2 Debugging and Logging ZebOS has a comprehensive debugging and logging facility in various protocols and components. This chapter describes how to start/stop debugging and logging using the NSM commands. For complete information about the logging commands, refer to the ZebOS NSM Command Reference. The protocol debug commands are in corresponding Command References. Debugging In the ZebOS implementation, every protocol has debug commands. Debug commands, when used with the parameters, log parameter-specific information. For example, using the debug ldp nsm command, results in the router writing all messages exchanged between LDP and NSM such as: interface, bandwidth and address updates. On using a debug command, the router continues to generate output until the no parameter is used with the command. The debug output and system error messages are written on the virtual terminal. Use the logging commands in the configure mode to redirect the debugging output to a file or syslog. You can set the logging levels by using parameters with these commands. Refer to the NSM Command Reference for details on these commands. Logging to stdout (terminal) To start debugging to stdout: 1. Turn on the debug options by using the relevant debug command. 2. Run the terminal monitor command. ZebOS> enable ZebOS# configure terminal ZebOS(config)# debug <protocol> (parameter) ZebOS(config)# exit ZebOS# terminal monitor Sample Output This is a sample output of the debug rsvp events command displayed on the terminal: ZebOS# terminal monitor Dec 2 16:41:49 localhost RSVP[6518]: RSVP: RSVP message sent to /32 via interface eth0 Dec 2 16:41:57 localhost RSVP[6518]: RSVP: Received an RSVP message of type RSVP Reservation from via interface eth0 Dec 2 16:41:57 localhost RSVP[6518]: RSVP: Received a RESV message from / 32 Logging information to a file or syslog To send logging information to a file: 1. Use the log file command and specify the path and file name where the information is to be logged. 3

10 Debugging and Logging 2. Turn on the debug option by using the relevant debug command. ZebOS> enable ZebOS# configure terminal ZebOS(config)# log file <filename> ZebOS(config)# debug <protocol> (parameter) When logging to a file, user can simultaneously log to stdout by running the terminal monitor command. 3. To log information in the system log, use the log syslog command: ZebOS(config)# log syslog The system log enables logging and analyzing configuration events and system error messages centrally. This helps in monitoring interface status, security alerts and CPU process overloads. It also allows real-time capturing of client debug output sessions. Use the no parameter with this command to disable system logging: ZebOS(config)# no log syslog Turning off debugging To turn off debugging, use the no debug or undebug command. When a protocol is specified with the no debug or undebug commands, debugging is stopped for the specified protocol. To stop all debugging, use the all parameter with these commands. ZebOS(config)# no debug bgp events or ZebOS# undebug all To turn off logging information to a file, use the no parameter with the log file command: ZebOS(config)# no log file (filename) 4

11 CHAPTER 3 Troubleshooting BGP In this chapter the topics are arranged sequentially. Depending on the event and time when the problem occurred, select the relevant section and follow steps sequentially. If the issue is not resolved, refer to the Miscellaneous Issues chapter in this document and the FAQs available at the Customer Support Web site. Refer to the ZebOS BGP Command Reference for details on commands used in this chapter. No BGP Adjacency Interface status Neighbor configuration Connectivity Firewall Use the show ip interface brief command to make sure that the interface is not administratively shutdown. Remove this configuration setting with the no shutdown command, if shutdown is configured. ZebOS# configure terminal ZebOS(config)# interface eth0 ZebOS(config-if)# no shutdown Use the show interface command to make sure that the interface is up. Make sure that the BGP configuration is correct. To establish BGP, configure a TCP session with another router using the neighbor remote-as command. When using ibgp: Make sure the two routers know how to reach each other s loopback addresses, if you have established ibgp using loopback interface. Typically, you have an IGP (say OSPF) running between the two routers. In this case, enable OSPF on the loopback interface or redistribute the loopback address into OSPF. Ping to each other s loopback address to ensure mutual reachability. When using ebgp: Make sure you have configured the multihop number for an ebgp neighbor that is not directly connected. Use the neighbor ebgp-multihop command to specify the maximum hop count to reach the neighbor. Make sure you can reach the neighbor using the ping A.B.C.D command. Verify if a firewall is present. If there is a firewall, it might be configured to block TCP packets. Verify the existing firewall configurations (in Linux) by using: ipchains -L Flush the existing firewall configurations by using: ipchains -F 5

12 Troubleshooting BGP Useful Show Commands show ip bgp This command displays the current state of the BGP routing table. When to use this command Use this command to check whether a specific route has been installed into the BGP routing table or not and to view information about various attributes of a route, such as, nexthop, metric and AS path. Sample Output BGP table version is 0, local router ID is Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, S stale, Origin codes: i - IGP, e - EGP,? - incomplete Network Next Hop Metric LocPrf Weight Path *> / i *> ? * ? *>i i Line by Line Description This routing table shows routes learned from both ibgp and ebgp peers. BGP table version is 0, local router ID is The Table version is 0. This version number increases whenever the table changes. The Router ID of the local router is Status codes: s suppressed, d damped, h history, p stale, * valid, > best, i - internal The possible status codes displayed at the beginning of the route entry. They display the status of the routes. Status Code Description Comments s suppressed Indicates that the route is suppressed and will not be advertised to the neighbors. d damped When the penalty of a flapping route exceeds the suppress limit, the route is damped and remains in a WITHDRAWN state until its penalty decreases below the reuse limit. h history When the penalty of a flapping route does not exceed the suppress limit, the route is not damped and BGP maintains a history of the flapping route. S stale When the BGP neighbor, from which a route is learned, is experiencing graceful restart, the route is retained in the BGP routing table and labeled by symbol p. * valid Indicates that the route is a valid route. When a route is not suppressed, damped or present in the history, it is a valid route. > best The selected route to be installed in the kernel routing table. i internal Indicates that the route is learned from an ibgp peer. An absence of this status code indicates that the route is learned from an ebgp peer. 6

13 Troubleshooting BGP Origin codes: i - IGP, e - EGP,? - incomplete Origin codes are at the end of each line in the routing table and provide information about where the route has originated from. Origin Code Description Comments i IGP Origin of the route is an Interior Gateway Protocol. e EGP Origin of the route is an Exterior Gateway Protocol.? incomplete Origin not known. Typically, redistributed routes from IGP. *> / i The absence of status code i indicates that it is learned from an ebgp peer. The > indicates that this route is selected to be installed in the kernel routing table. Its network address is /24. The IP address of the nexthop for this route is The weight parameter applies only to routes within an individual router. Since this route was learned from a peer, it has a default weight of 0. All routes generated by the local router have a weight of 32,768. The path attribute 1 4 indicates that the prefix advertisement passed through the ASs AS1 and AS4. The origin code i indicates that the prefix was added by network statement at originating AS. *> ? * ? The same prefix is learned from two different ASs, AS1 and AS3. The route learned from AS1 is chosen as the best route because AS1 has a lower Router ID ( ) than AS2 ( ). Although the Metric or MED (MULTI_EXIT_DISC) of the route learned from AS1 is higher (200) than the route learnt from AS3 (100), this attribute is not used in the best path selection decision because MEDs are compared only if the first (neighboring) AS is the same in the two paths. The origin code? indicates that the routes are learned through redistribution. *>i i The route is learned through an ibgp peer as indicated by the status code i. The LOCAL_PREF attribute of the route, which is used only with the local AS, is set to 100 (the default value). show ip bgp summary This command displays the state summary of BGP neighbor connections. When to use this command Use this command to check the state of the BGP neighbor connections and to view information about the: Current state of BGP neighbor connections. Number of prefixes received from specific neighbor after BGP connection is established. Sample Output BGP router identifier , local AS number 10 0 BGP AS-PATH entries 0 BGP community entries 7

14 Troubleshooting BGP Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd :22:53 2 Total number of neighbors 1 Line by Line Description BGP router identifier , local AS number 10 0 BGP AS-PATH entries 0 BGP community entries BGP router ID is and the local router AS number is 10. There are no BGP AS-PATH or community entries :22:53 2 There is only one BGP neighbor available, with an IP address and AS Number 20. The neighbor uses BGP version messages are received by the local BGP messages are sent by the local router since the BGP connection has been established. The current BGP routing table version (TblVer) is 0. When the table changes, the version will increase. The input queue (InQ) indicates that there are no received messages waiting in the input queue for further processing. The output queue (OutQ) indicates that there are no messages waiting in the output queue to be sent. The connection has been up for 16 hours, 22 minutes and 53 seconds. The local router has received two prefixes from this neighbor. show ip bgp neighbors This command gives detailed information about all BGP peering sessions that the local system is currently involved in. You can view information pertaining to a specific neighbor, by specifying the IP address of the neighbor with this command (show ip bgp neighbors <ipaddress>). Sample Output (on ) ZebOS# show ip bgp neighbors BGP neighbor is , remote AS 2, local AS 1, external link BGP version 4, remote router ID BGP state = Established, up for 00:00:56 Last read 00:00:01, hold time is 180, keepalive interval is 60 seconds Neighbor capabilities: Route refresh: advertised and received (old and new) Address family IPv4 Unicast: advertised and received Received 4 messages, 0 notifications, 0 in queue Sent 5 messages, 0 notifications, 0 in queue Route refresh request: received 0, sent 0 Minimum time between advertisement runs is 30 seconds For address family: IPv4 Unicast BGP table version 1, neighbor version 1 Index 1, Offset 0, Mask 0x2 Community attribute sent to this neighbor (both) 2 accepted prefixes 8

15 Troubleshooting BGP 1 announced prefixes Connections established 1; dropped 0 Local host: , Local port: 2713 Foreign host: , Foreign port: 179 Nexthop: Nexthop global: aaaa:bbbb::77 Nexthop local: fe80::204:75ff:fe9e:c936 BGP connection: non shared network Read thread: on Write thread: off The following is a line-by-line description of the output: BGP neighbor is , remote AS 2, local AS 1, external link The IP address of the BGP neighbor is The AS number of the neighbor is 2. The AS number of the local system is 1 The type of BGP peering is external (ebgp). If the neighbor is in the same AS, this line would display internal link. BGP version 4, remote router ID The negotiated BGP version for this peering session is BGP4. The neighbor s Router ID is BGP uses the highest loopback address as the Router ID. If no loopback interface is configured, BGP uses the highest configured IP address on a system. BGP state = Established, up for 00:00:56 The peering session is in an Established state.the session can be in a Idle, Active, OpenSent, OpenConfirm or Established state. Only after the neighbor session is in an Established state, the exchange of routing information begins between peers. Detailed information about BGP states is in the Section 8 of the IETF RFC A Border Gateway Protocol - 4 or the latest IETF BGP (draft version 22). The current peering session has been running for 56 seconds. Last read 00:00:01, hold time is 180, keepalive interval is 60 seconds The time elapsed since a message was last received from this neighbor is 00:00:01. The maximum time that can elapse between successive messages from this neighbor is 180 seconds. If no message is received for 180 seconds, this neighbor will be declared dead. The time interval between successive keepalive messages is 60 seconds. Typically, the hold time value is set to three times the keepalive interval. Neighbor capabilities: Route refresh: advertised and received (old and new) Address family IPv4 Unicast: advertised and received The Route Refresh and Address Family IPv4 unicast capabilities are advertised and received from the neighbor. Received 4 messages, 0 notifications, 0 in queue Sent 5 messages, 0 notifications, 0 in queue Received 4 messages and 0 notifications from the neighbor and sent 5 messages and 0 notifications to the neighbor. There are 0 messages to be or received from the neighbor. Route refresh request: received 0, sent 0 Minimum time between advertisement runs is 30 seconds 9

16 Troubleshooting BGP No route refresh requests have been sent or received from the neighbor. The minimum advertisement interval for the neighbor is 30 seconds. This means that the minimum time gap between successive route updates sent to the neighbor is 30 seconds. Generally, a jitter (of 25%) is applied to this time interval, which means that if the time between advertisements is configured as 30, successive advertisements can have a time gap of as low as 22.5 (after applying a 25% jitter to the 30 seconds, which is 7.5 seconds). For address family: IPv4 Unicast BGP table version 1, neighbor version 1 Index 1, Offset 0, Mask 0x2 Community attribute sent to this neighbor (both) 2 accepted prefixes 1 announced prefixes The peers have exchanged IPv4 Unicast address family capability, which is the default. For each of the address families agreed upon, a separate table is maintained by BGP. This can be seen from the BGP table version number (1). One prefix (route) is advertised to and 2 received from the neighbor. Also, both the community attributes (standard and extended) have been sent. Connections established 1; dropped 0 The router has established a TCP connection once, and the two peers have agreed to speak BGP with each other once. The good connection has not failed or brought down (0). Local host: , Local port: 2713 The IP address and the port number on the local system used for the peering session are and Foreign host: , Foreign port: 179 The IP address and the port 179 is used for the neighbor. BGP always uses the TCP port number 179. In this example, the local system ( ) has initiated the TCP connection, thus, the port number on the peer is 179. If the connection had been initiated by the remote peer, 179 would be a port number on the local system. Nexthop: Nexthop global: aaaa:bbbb::77 Nexthop local: fe80::204:75ff:fe9e:c936 The IP address of the next-hop ( ) is used to reach the neighbor. The BGP peers ebgp or ibgp do not require to be directly connected. Peering sessions can be set up across multiple hops. In this example, since the neighbors are directly connected, the IP address of the local system ( ) is listed as the next-hop. The global IPv6 address of the nexthop is aaaa:bbbb::77. The link-local IPv6 address of the next-hop is fe80::204:75ff:fe9e:c936. BGP connection: non shared network The peering session is running on a non shared network. Read thread: on Write thread: off The read/write status for the socket shared with this particular peer is off. Both are generally in off state when the state of the BGP session between peers is Idle. 10

17 CHAPTER 4 Troubleshooting OSPF In this chapter the topics are arranged sequentially. Depending on the event and time when the problem occurred, select the relevant section and follow steps sequentially. If the issue is not resolved, refer to the Miscellaneous Issues chapter in this document and the FAQs available at the Customer Support Web site. Refer to the ZebOS OSPF Command Reference for details on the commands used in this chapter. No OSPF Adjacency Interface Status OSPF Enabled on the Interface Use the show ip interface brief command to make sure that the interface is not administratively shutdown. Remove this configuration setting with the no shutdown command, if shutdown is configured. ZebOS# configure terminal ZebOS(config)# interface eth0 ZebOS(config-if)# no shutdown Use the show interface command to make sure that the interface is up. Make sure that OSPF is enabled on the interface. To enable OSPF on a particular interface, use the network area command with a specified Area ID. Use the show ip ospf interface to confirm that OSPF is enabled for the interface. Sample output eth2 is up, line protocol is up Internet Address /24, Area , MTU 1500 Router ID , Network Type BROADCAST, Cost: 10 Transmit Delay is 1 sec, State DR, Priority 1 Designated Router (ID) , Interface Address Backup Designated Router (ID) , Interface Address Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:05 Neighbor Count is 1, Adjacent neighbor count is 1 Crypt Sequence Number is 0 Hello received 625 sent 645, DD received 3 sent 4 LS-Req received 1 sent 1, LS-Upd received 5 sent 13 LS-Ack received 8 sent 5, Discarded 0 11

18 Troubleshooting OSPF Passive Interface Exchange of Hello Packets Mismatch between Hello Parameters Mismatch between MTU sizes Make sure that interface is not configured as a passive interface using the show run command:! router ospf passive interface eth0! If the interface is configured as passive (as shown above), remove this configuration setting by using this command: no passive interface eth0 Check on the interface to make sure that OSPF Hello packets are being sent and received on the interface. You can use either packet sniffer (such as, Ethereal or TCP dump) or ZebOS log messages to verify the hello packet. To turn on ZebOS logging, type: ZebOS# configure terminal ZebOS(config)# debug ospf event ZebOS(config)# debug ospf packet hello To display the logging message on the terminal, type: ZebOS# terminal monitor It is possible that there is a mismatch between Hello parameters. Make sure that you have specified the same hello interval and dead interval values on both machines by using the show ip ospf interface command on each machine. Run show ip ospf neighbor, if you see the neighbor but the state is not full. Make sure that both routers have the same MTU size for the interfaces. 12

19 Troubleshooting OSPF Useful Show Commands show ip ospf interface This command displays interface information for OSPF. When to use this command Use this command when you want to check the interfaces enabled for an OSPF process. It provides important information about the OSPF parameters. Confirm that the OSPF parameters match that of the neighbors. If the intended interfaces are not shown in the OSPF information, check the configuration to make sure that the IP address of the missing interface is included. Sample Output eth1 is up, line protocol is up Internet Address /24, Area , MTU 1500 Router ID , Network Type BROADCAST, Cost: 10, TE Metric 0 Transmit Delay is 1 sec, State DR, Priority 1 Designated Router (ID) , Interface Address Backup Designated Router (ID) , Interface Address Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:05 Neighbor Count is 1, Adjacent neighbor count is 1 Crypt Sequence Number is 0 Hello received 19 sent 106, DD received 4 sent 3 LS-Req received 1 sent 1, LS-Upd received 3 sent 3 LS-Ack received 2 sent 3, Discarded 0 Description of displayed fields Internet Address Area MTU Transmit Delay Priority Hello Dead Wait Retransmit Hello due in Neighbor Count Adjacent neighbor The IP address and subnet mask of the interface. The OSPF area to which the interface belongs. The Maximum Transmission Unit (MTU) of the interface. The transmit delay of the interface. The OSPF priority of the current interface. It is used for election of Designated Router (DR) and Backup Designated Router (BDR). The OSPF hello-interval. The OSPF dead-interval. The Hello wait-interval. The period, in seconds, for which the router waits between retransmissions of OSPF packets that have not been acknowledged. The time period for which router expects to receive hello packet. The OSPF neighbor count. The OSPF adjacent neighbor count. 13

20 Troubleshooting OSPF Crypt Sequence Number Hello received 19 sent 106, DD received 4 sent 3 LS-Req received 1 sent 1, LS-Upd received 3 sent 3 LS-Ack received 2 sent 3, Discarded 0 This is used for authentication. This line shows that this router received 19 and sent 106 Hello packets. It has received 4 and sent 3 DD packets out. This line indicates that this router received and sent 1 LSA request. It sent and received 3 LSA updates. This line indicates that this router received 2 and sent 3 LSA acknowledgements. It discarded no LSA acknowledgement. show ip ospf neighbor This command displays information about OSPF neighbors. When to use this command Use this command to check OSPF neighbors and their states. If the expected neighbors do not show the OSPF information, make sure that the OSPF parameters match the intended neighbors and they are configured in the same area. Sample Output ZebOS# show ip ospf neighbor OSPF process 100: Neighbor ID Pri State Dead Time Address Interface RXmtL RqstL DBsmL Full/Backup 0:00: eth1: OSPF process Neighbor ID Pri State Dead Time Address Interface The OSPF process involved. The OSPF Router ID of the neighbor. The OSPF priority of the neighbor. The functional state of the OSPF neighbor. If a new Hello is not received within this duration, the neighbor is declared dead. The IP address of neighbor s interface attached to the network. The interface attached to the network on which the neighbor is located. show ip ospf database This command displays information about OSPF link-state database on the router. Sample Output QA72# show ip ospf database OSPF Router process 100 with ID ( ) Router Link States (Area ) Link ID ADV Router Age Seq# CkSum Link count 14

21 Troubleshooting OSPF x x90de x x Net Link States (Area ) Link ID ADV Router Age Seq# CkSum x x0bef Summary Link States (Area ) Link ID ADV Router Age Seq# CkSum Route x x / x xc2c / x x23fb /32 Description of displayed fields Link ID Link ID has a different meaning for different types of Link-State Advertisements. Link ID for Router Link States: Depends on the type of network the router connects to: Point to Point network Neighbor s Router ID. Transit network IP address of the Designated Router s interface. Stub network IP network or subnet address Virtual link Neighbor s Router ID. Link ID for Net Link States: The IP address of the DR's interface. Link ID for Summary Link States: The IP address of the network or subnet being advertised. ADV Router The router ID of the router advertising the LSA. Age The age of the LSA. Seq# The sequence number of the LSA. This number increments each time a new instance of the LSA originates. This update helps other routers identify the most recent instance of the LSA. CkSum The Fletch checksum of the complete LSA except the Age field. 15

22 Troubleshooting OSPF 16

23 CHAPTER 5 Troubleshooting RIP In this chapter the topics are arranged sequentially. Depending on the event and time when the problem occurred, select the relevant section and follow steps sequentially. If the issue is not resolved, refer to the Miscellaneous Issues chapter in this document and the FAQs available at the Customer Support Web site. Refer to the ZebOS RIP Command Reference for details on commands used in this chapter. No RIP Adjacency Interface Status RIP enabled on Interface Passive Interface Use the show ip interface brief command to make sure that the interface is not administratively shutdown. Remove this configuration using the no shutdown command, if shutdown is configured. ZebOS# configure terminal ZebOS(config)# interface eth0 ZebOS(config-if)# no shutdown Use the show interface command to make sure that the interface is up. Confirm that RIP is enabled on the interface. To enable RIP on a particular interface, use the network command. Use the show ip rip interface to make sure that RIP is enabled for the interface. Sample Output ZebOS# show ip rip interface fxp0 is up, line protocol is up Routing Protocol: RIP Receive RIP packets Send RIP packets Passive interface: Disabled Split horizon: Enabled with Poisoned Reversed IP interface address: /16 Make sure that the interface is not configured as a passive interface using the show run command:! router rip passive interface eth0! If the interface is configured as passive (as shown above), remove this configuration setting by using this command: no passive interface eth0 17

24 Troubleshooting RIP Exchange of RIP Advertisements RIP Version Mismatch Firewall Make sure that RIP advertisements are being sent and received on the interface. You can use either a packet sniffer (such as, Ethereal or TCP dump) or the ZebOS log messages to verify the RIP advertisements. To turn on ZebOS logging, type: ZebOS# configure terminal ZebOS(config)# debug rip event ZebOS(config)# debug rip packet detail To display the logging message on the terminal, type: ZebOS# terminal monitor One router configured as RIPv1 and the other router as RIPv2 results in no RIP adjacency. Configure the router running RIPv2 as follows:! interface eth1 ip rip send version 1-compatible ip rip receive version 1 2! Verify if a firewall is present. If there is a firewall, it blocks the UDP packet. You must remove the firewall if you have one. To display the existing firewall configurations, in Linux, use: ipchains -L Flush the existing firewall configurations by using: ipchains -F 18

25 Troubleshooting RIP Useful Show Commands show ip rip interface This command displays information about RIP interfaces. When to use this command Use this command to verify that RIP is enabled on an interface. Sample Output ZebOS# show ip rip interface eth1 eth1 is up, line protocol is up Routing Protocol: RIP Receive RIP packets Send RIP packets Passive interface: Disabled Split horizon: Enabled with Poisoned Reversed IP interface address: /24 Line by line description In the above output: eth1 is up, line protocol is up Routing Protocol: RIP These lines denote that the interface is UP and RIP is enabled. Receive RIP packets Send RIP packets These lines indicate that the interface is capable of receiving/sending both RIP version 1 and 2 packets, which is the default. If RIP is configured to send only version 1 packets using the ip rip send version 1 command, the output displays: Send RIPv1 packets only Passive interface: Disabled This line denotes that the specified interface is not passive and can send and receive RIP updates. If passive interface is configured using the passive-interface <IFNAME> command, RIP updates are received but not sent. This configuration is required when a router does not want to advertise itself but still wants to learn RIP routes. Split horizon: Enabled with Poisoned Reversed This line denotes that the split-horizon with poisoned reversed feature is enabled on the displayed interface (eth1). This means that routes will not be advertised on the interface from which they are learnt avoiding the problem of counting to infinity. IP interface address: /24 These lines display the IPv4 address of the RIP enabled interface. 19

26 Troubleshooting RIP show ip rip database This command displays the different routes learnt by RIP. When to use this command Use this command to view details of all the routes learnt by RIP. Sample Output ZebOS# show ip rip database Codes: R - RIP, K - Kernel, C - Connected, S - Static, O - OSPF, I - IS-IS, B - BGP Network Next Hop Metric From If Time R / eth1 02:47 O / eth2 03:06 S /24 1 eth1 Line by line description In the above output: Codes: R - RIP, K - Kernel, C - Connected, S - Static, O - OSPF, I - IS-IS, B - BGP Refer to the show ip route command description for details about these codes. Network Next hop Metric From If Time Is the network prefix Is the IPv4 address of the nexthop router. Is the metric to reach the network prefix. Is the IPv4 address of the neighbor's interface. Is the local router's interface through which the router reaches the Network prefix. Is the duration for which the network prefix is stored in the RIP routing table. R / eth1 02:47 This line denotes a RIP route learnt from a neighbor ( ) through interface eth1. This route belongs to the /24 network, its metric value is 2 and its nexthop is It will remain in the RIP routing table for 2 minutes 47 seconds. O / eth2 03:06 This line denotes an OSPF route learnt from a neighbor ( ) through interface eth2. This route belongs to the /24 network, its metric value is 2 and nexthop is It will remain for 3 minutes and 6 seconds in the RIP routing table. S /24 1 eth1 This line denotes a static route connected through interface eth1. It has a metric value of 1 to reach the network prefix. 20

27 CHAPTER 6 Troubleshooting LDP In this chapter the topics are arranged sequentially. Depending on the event and time when the problem occurred, select the relevant section and follow steps sequentially. If the issue is not resolved, refer to the Miscellaneous Issues chapter in this document and the FAQs available at the Customer Support Web site. Refer to the ZebOS LDP Command Reference for details on commands used in this chapter. LDP Session is not UP Selection of the Transport Address Make sure that the transport address is selected correctly by the system. The transport address is the IP address that the LDP router advertises in its Hello message so that other routers can communicate using this IP address while setting up a TCP connection for the LDP session. F5 Networks recommends that the loopback address be used as a transport address so that link loss on any one interface does not cause the LDP session to go down. Use the show ldp command to verify the status of the transport address. The following is a section from the output of the show ldp command: Router# show ldp Router ID : LDP Version : 1 Global Merge Capability : N/A Label Advertisement Mode : Downstream Unsolicited Label Retention Mode : Liberal... Targeted Hello Receipt : Disabled Transport Address data : Labelspace 0 : (in use) Import BGP routes : No In this show output, the transport address data indicates that is the transport address and is using 0 labelspace. When loopback address is configured, it is automatically selected as transport address. If no loopback address is available, the LDP process selects the first available physical interface IP address. 21

28 Troubleshooting LDP Reachability to transport address Verify the status of LDP Targeted peers When the transport address is verified to be correct on the peering systems, make sure that the transport address of the remote peer is reachable from both the routers. To verify that the remote transport address is reachable, ping the remote transport address. Use the show ip route command and check if there is a route to the neighbor s transport address. Sample Output... S /24 [1/0] is directly connected, eth0 O /32 [110/30] via , eth1, 15:44:20 C /32 is directly connected, lo O /32 [110/20] via , eth1, 17:45:31 C /8 is directly connected, lo... In the output above, /32 is the neighbor s transport address and can be reached via If there is no route to the neighbor s transport address: Add a static route to the neighbor s transport address. Or Use an IGP (OSPF) to reach the neighbor s transport address. Use the show ldp interface command to verify the status of LDP. QA16# show ldp interface Interface LDP Identifier Label-switching Merge Capability lo :0 Disabled N/A eth :0 Disabled N/A eth :0 Enabled Merge capable eth :0 Enabled Merge capable If the label-switching is disabled on an interface, use the show run command to ensure that LDP and label-switching are enabled on that interface. The configuration should show as follows:! interface eth1 label-switching ip address /24 enable-ldp! Use the show run command to ensure that targeted peer hello receipt is enabled. If not, then run the targeted-peer-hello-receipt command to configure the LSR to respond to requests for targeted hello messages. 22

29 CHAPTER 7 Troubleshooting VRRP In this chapter the topics are arranged sequentially. Depending on the event and time when the problem occurred, select the relevant section and follow steps sequentially. If the issue is not resolved, refer to the Miscellaneous Issues chapter in this document and the FAQs available at the Customer Support Web site. Refer to the ZebOS VRRP Command Reference for details on commands used in this chapter. The following topology has been used for illustration. Host /24 VRID = 1 eth3 MASTER R1 eth2 eth3 BACKUP R2 eth /24 Host1 Host2 Host3 Incorrect VRRP States Interface running Make sure the interfaces are up and running by using the show interface command. In the following sample output interface eth1 is: ZebOS# show interface eth1 Interface eth1 Hardware is Ethernet, address is 0002.b3d4.436f index 3 metric 1 mtu 1500 <UP,BROADCAST,RUNNING,MULTICAST>... input errors 0, length 0, overrun 0, CRC 0, frame 0, fifo 0.. If the interface is down: Use no shutdown command, in the interface mode, to bring up the interface. Or Use the ifconfig <IFNAME> up command to bring up the interface. 23

30 Troubleshooting VRRP Reachability of routers Make sure that both VRRP routers can reach each other by pinging. ZebOS# ping PING ( ) 56(84) bytes of data. 64 bytes from : icmp_seq=1 ttl=255 time=0.202 ms 64 bytes from : icmp_seq=2 ttl=255 time=0.201 ms If both routers cannot reach each other, check the network connections for the default Master and default Backup routers. Advertisement Intervals on both routers Check the advertisement interval on Master and Backup routers. The advertisement interval must be the same on both. The default advertisement interval = 1. Use the advertisement-interval command, in Router mode, to configure the advertisement interval. 24

31 CHAPTER 8 Troubleshooting PIM-SM In this chapter the topics are arranged sequentially. Depending on the event and time when the problem occurred, select the relevant section and follow steps sequentially. If the issue is not resolved, refer to the Miscellaneous Issues chapter in this document and the FAQs available at the Customer Support Web site. Refer to the ZebOS PIM-SM Command Reference for details on commands used in this chapter. No PIM adjacency Interface Status PIM Enabled on the Interface Adjacency between ZebOS and CISCO Use the show run command to make sure that the interface is not administratively shutdown. If shutdown is configured, remove this configuration with the no shutdown command. ZebOS# configure terminal ZebOS(config)# interface eth0 ZebOS(config-if)# no shutdown Use the show interface command to make sure that the interface is up. Make sure that PIM-SM is enabled on the interface by using the show ip pim sparse-mode interface command. If you are trying to establish adjacency between ZebOS and CISCO and are not successful, use the ip pim exclude-genid command on the interface. Some old CISCO IOS do not recognize the GenID option in the PIM-SM Hello packet and discard the packet. No BSR and RP information Unicast Routing Configuration Check your Unicast routing configuration to make sure that you can reach BSR and RP. Use the show ip route command to display the unicast routing table. RP not advertised in the BSR CISCO BSR and ZebOS RP This happens when CISCO is a BSR and ZebOS is the candidate RP. In this case, you must configure the following command, in the Configure mode, on ZebOS candidate RP router. ip pim crp-cisco-prefix 25