Smarts IP: No Router Down alarm between two routers connected by DS2 or SONET links

Products

• VMware Smart Assurance

Issue/Introduction

Symptoms:


There are no router down event between two routers connected by a DS2 or SONET links.

Environment

VMware Smart Assurance - SMARTS

Cause

1. When topology is reduced to include only two routers and one connection between the routers, the Router Down event requires three symptoms  self MightBeDown, peer MightBeDown and peer interface DownOrFlapping.  However, peer MightBeDown and peer interface DowOrFlapping can never be observed at the same time from the same peer, therefore prevented generating Router Down event.
2. When a router is powered down, it would normally cause all the physically connected peer interfaces (the lower physical interfaces) of the remote peer router to be signaled as down as well so that the remote routers may reroute packets via different interfaces.  Therefore in practice, more likely than not, interface Down is not the root cause of the peer router Down as the current existing model specified.  Rather the opposite that the router Down causes the connected remote peer interface to become DownOrFlapping.  This is because the connections between Peer Routers are normally of the types such as DS1/3 or SONET.  These types of connections would signal both ends down if one end is powered off.

Resolution

Fix will be included in future patch release for IP 9.4.1 and 9.4.2.