CDM-840 Remote Router MN-CDM840
Appendix J Revision 3
J–24
J.4.3 Highly Degraded Remote
In the ACM/VCM Outbound channel, when a remote either highly degrades or loses
communication, prior to FW Ver. 1.6.2.X the ACM/VCM controller in the CTOG-250 would assign
a low MODCOD for traffic destined to a given remote, and attempt to honor any configured CIR.
As a result, the number of symbols used to meet CIR for that degraded remote was
disproportionate and resulted in a network-wide reduction in throughput.
The Highly Degraded Remote feature allows you to specify a “CIR Threshold MODCOD” on each
CDM-840 that is automatically communicated to the CTOG-250. If the remote fades below this
MODCOD and the Outbound link is fully utilized, the CTOG-250 will no longer try to maintain the
CIR for traffic destined to that remote. Rather, the ACM/VCM QoS system will attempt to
maintain a “fair share” of symbols for a highly degraded remote based upon the nominal
number of symbols assigned to each QoS Group and its configured CIR.
The data rate at which a remote is clamped will scale as the remote degrades below the “CIR
Threshold MODCOD” – i.e., the more it fades, the more the data rate is clamped.
As shown in Figure J-6: Use the CDM-840 HTTP Interface ‘Configuration | WAN | Demod |
ACM’ page to configure the “CIR Threshold MODCOD.” You can use the CTOG-250 HTTP
Interface ‘Configuration | WAN | Remotes Sites | Configuration’ page to view the currently
configured value.
Figure J-6. Highly Degraded Remote Function – CDM-840 and CTOG-250 HTTP Interfaces
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