Action to Take for ARP Connectivity Issues
Question
You are troubleshooting ARP connectivity issues for an Ethernet interface on an IOS XR network that runs IS-IS.
You verify that the IGP protocol is running, but an ARP entry has not yet been created.
Which action should you take?
Answers
Explanations
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A. B. C. D.C.
In an IOS XR network that runs IS-IS, if an ARP entry has not yet been created despite the IGP protocol running, it could indicate an ARP connectivity issue. ARP is used to map IP addresses to physical MAC addresses on the local network. Here are the possible steps to troubleshoot the issue:
A. Debugging ping packets will not help resolve an ARP connectivity issue, as ping uses the ICMP protocol, which operates at a higher layer of the OSI model. Debugging ping packets will only provide information about the reachability of the destination IP address and any network hops along the way.
B. Debugging ARP could provide more information about the ARP process and any potential issues. The command "debug arp" can be used to view debug messages related to ARP. However, this command can produce a large amount of output and should be used with caution. It's generally recommended to use debugging only as a last resort due to the potential impact on system performance.
C. Pinging the connected neighbor can be useful to verify basic connectivity between devices, but it may not directly resolve an ARP connectivity issue. Pinging can help determine if there is a problem with the physical connectivity or if a route is missing, but it will not necessarily provide information about ARP.
D. Verifying the RIB table routes can be helpful to determine if there are any routing issues that could be preventing ARP from functioning properly. The RIB (Routing Information Base) is a database that contains routing information learned from various sources, including the IGP protocol. If the RIB table routes are incorrect or incomplete, this can impact ARP. The command "show route" can be used to view the RIB table routes.
Therefore, in this scenario, the best course of action would be to check the RIB table routes to see if there are any routing issues that may be preventing ARP from creating an entry. If the RIB table routes appear correct, then debugging ARP may be a next step to investigate further.
