Installation guide

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Release Notes for Cisco uBR7200 Series for Cisco IOS Release 12.1 T
78-10643-04 Rev. B0
New and Changed Information
New Software Features in Release 12.1(1a)T1
The following new software features are supported by the Cisco uBR7200 Series Universal Broadband
Routers in Cisco IOS Release 12.1(1a)T1.
Baseline Privacy Interface MIB
Cisco uBR7200 Series Universal Broadband Routers now include support for the DOCSIS Baseline
Privacy Interface (BPI) MIB. This allows an SNMP manager to monitor and manage the router’s BPI
configuration, including whether BPI is enabled, status of current authorization keys, current timeout
values, real-time status counters, and additional information about authorization errors.
Note The SNMP manager must load the DOCS-BPI-MIB.my MIB to access the BPI attributes.
Bi-Directional Protocol Independent Multicast (PIM)
Bi-directional Protocol Independent Multicast (bidir-PIM) is an extension of Protocol Independent
Multicast sparse mode (PIM SM), which implements shared sparse trees with bidirectional flow of data.
In contrast to PIM SM, bidir-PIM avoids keeping a source-specific state in routers and therefore allows
multicast distribution trees to scale to an arbitrary number of sources.
Bidirectional flow allows improved data delivery to receivers close to the source, because the traffic
traveling upstream to the rendezvous point (RP) is “turned around” and forwarded on downstream
branches. Bidirectional shared trees can therefore distribute datagrams from sources to the RP and
directly to receivers. Moreover, the bidir-PIM protocol does not build source trees from sources to the
RP or to receivers. Instead, source transmissions travel up the shared tree toward the RP and to receivers
along the way. The RP only needs to forward datagrams downward on those branches of the shared tree
not covered by the path from the source to the RP.
When compared to unidirectional trees in PIM SM, bidir-PIM reduces the amount of state that routers
must explicitly keep. Each router in a bidirectional multicast routing domain needs to only keep state
for the group and not each source sending to each group. Explicit joins are used for members to join the
shared tree. However, sources do not use registers to get their data on the shared tree.
DOCSIS Quality of Service Enhancements
A number of DOCSIS quality of service (QoS) enhancements have been added to Cisco IOS
Release 12.1(1a)T1; these features parallel some of those that are expected in the DOCSIS 1.1
specification when it is finalized.
Note These QoS enhancements are in addition to the currently existing QoS traffic shaping and
tiered best effort features.
• Concatenation Support—DOCSIS Concatenation combines multiple upstream packets into one
packet to reduce packet overhead and overall latency, as well as increase transmission efficiency.
Using concatenation, a DOCSIS cable modem needs to make only one bandwidth request for a
concatenated packet, as opposed to making a different bandwidth request for each individual
packet; this technique is especially effective for bursty real-time traffic, such as voice calls.