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Chapter 15: Interface IP Configuration

STANDARD Revision 1.0 C4® CMTS Release 8.3 User Guide

 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.

Arris C4C User Manual

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