Data Center LAN Migration Guide - Juniper Networks
Data Center LAN Migration Guide - Juniper Networks
Data Center LAN Migration Guide - Juniper Networks
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<strong>Data</strong> <strong>Center</strong> <strong>LAN</strong> <strong>Migration</strong> <strong>Guide</strong><br />
OSI Layer 2: <strong>Data</strong> Link Troubleshooting<br />
Below are some common steps to assist in troubleshooting issues at Layer 2 in the access and aggregation tiers:<br />
• Are the devices utilizing DHCP to obtain an IP addresses? Is the Dynamic Host Configuration Protocol (DHCP)<br />
server functioning properly so that host devices receive an IP address assignment from the DHCP server? If routed, is<br />
the DHCP request being correctly forwarded?<br />
• monitor traffic interface ge-0/0/0 command provides a tool for monitoring local traffic. Expect to see all packets<br />
that are sent out and received to and from ge-0/0/0. This is particularly useful to verify the Address Resolution<br />
Protocol (ARP) process over the connected <strong>LAN</strong> or V<strong>LAN</strong>. Use the show arp command to display ARP entries.<br />
• Is the V<strong>LAN</strong> in question active on the switch? Is a trunk active on the switch that could interfere with the ability<br />
to communicate? Is the routed V<strong>LAN</strong> interface (RVI) configured with the correct prefix and attached to the<br />
corresponding V<strong>LAN</strong>? Is VRRP functioning properly and showing one unique routing node as master for the virtual IP<br />
(VIP) address?<br />
• Virtual Chassis, Layer 3 uplinks, inverted U designs, and VPLS offer different alternatives to prevent L2 data<br />
forwarding loops in a switching infrastructure without the need to implement Spanning Tree Protocols (STPs).<br />
Nevertheless, it is common best practice to enable STP as a protection mechanism to prevent broadcast storms in<br />
the event of a switch misconfiguration or a connection being established by accident between two access switches.<br />
Virtual Chassis Troubleshooting<br />
Configuring a Virtual Chassis is essentially plug and play. However, if there are connectivity issues, the following<br />
section provides the relevant commands to perform operational analysis and troubleshooting. To troubleshoot the<br />
configuration of a Virtual Chassis, perform the following steps.<br />
Check and confirm Virtual Chassis configuration and status with the following commands:<br />
• show configuration virtual-chassis<br />
• show virtual-chassis member-config all-members<br />
• show virtual-chassis status<br />
Check and confirm Virtual Chassis interfaces:<br />
• show interfaces terse<br />
• show interfaces terse vcp*<br />
• show interfaces terse *me*<br />
Verify that the mastership priority is assigned appropriately:<br />
• show virtual-chassis status<br />
• show virtual-chassis vc-port all-members<br />
Verify the Virtual Chassis active topology and neighbors:<br />
• show virtual-chassis active-topology<br />
• show virtual-chassis protocol adjacency<br />
• show virtual-chassis protocol database extensive<br />
• show virtual-chassis protocol route<br />
• show virtual-chassis protocol statistics<br />
In addition to the verifications above, also check the following:<br />
• Check the cable to make sure that it is properly and securely connected to the ports. If the Virtual Chassis port (VCP)<br />
is an uplink port, make sure that the uplink module is model EX-UM-2XFP.<br />
• If the VCP is an uplink port, make sure that the uplink port has been explicitly set as a VCP.<br />
• If the VCP is an uplink port, make sure that you have specified the options (pic-slot, port-number, member-id)<br />
correctly.<br />
58 Copyright © 2012, <strong>Juniper</strong> <strong>Networks</strong>, Inc.
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