Chapter 15: Interface IP Configuration
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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The partner side is not LACP forwarding.
An LACP timeout occurs, indicating that the partner is LACP out-of-sync.
Feature Interactions
It should be stressed that LAG works with all the supported routing protocols; however, the purpose of this section is to
note unexpected effects on other supported features.
Link Overload Protection
If Equal Cost Multipath (ECMP) is being utilized with LAGs, and links in a particular LAG go down, traffic will continue to be
sent on the remaining link(s); however, a point may be reached where the remaining link(s) become overloaded. The
Minimum Number of Links feature helps prevent overloading of the remaining links by setting the number of links that can
be lost before ECMP reroutes using a different LAG.
BSoD
Performance of the BSoD feature is enhanced with link aggregation. Without LAGs, a primary and a secondary (backup) 1G
link are used for BSoD, one on each RCM. All traffic goes in and out the primary link. If the primary side RCM goes down, a
side switch occurs and the former backup link then becomes primary. However, there is no immediate notification to the
northbound router that a shift has occurred. The router first needs to detect "link down" on the old primary link before it
can shift traffic to send to the new primary link of the C4/c CMTS. This traffic shift is therefore delayed.
Using a LAG that spans RCMs eliminates the need for a BSoD backup link because all data is passed by means of the LAG. If
an RCM goes down, only a portion of the links are impacted in the LAG, and it is still operational with the same capacity as
the previous primary link. Because the northbound router is communicating over just the one LAG for all traffic, if an RCM
goes down there is no need to shift traffic. Therefore there is no delay.
Command Line Interface
CLI commands related to specific functions unique to LAG configuration and usage are provided in the table below. For
additional details concerning these commands refer to Command Line Descriptions.
