Category Archives: Notes

LLQ and RSVP

Ref: http://www.cisco.com/en/US/docs/ios/12_1t/12_1t3/feature/guide/rsvp_llq.html Admission Control Combined with Low Latency Queueing LLQ provides a means to forward voice traffic with strict priority The LLQ is not supported on any tunnels. RSVP support for LLQ on Frame Relay permanent virtual circuits (PVCs) and … Continue reading

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pattern ext-to-ext

The Cisco SRS Telephony router provides flexibility for the integration with any legacy voice-mail system. You can configure multiple tags and tokens for each pattern, depending on the voice-mail system and type of access. The tag in the configuration pattern … Continue reading

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Voice Over IP – Per Call Bandwidth Consumption

Bandwidth Calculation Formulas These calculations are used: Total packet size = (L2 header: MP or FRF.12 or Ethernet) + (IP/UDP/RTP header) + (voice payload size) PPS = (codec bit rate) / (voice payload size) Bandwidth = total packet size * … Continue reading

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MTP Over Subscription

If all n MTP transcoding sessions are utilized, and an n + 1 connection is attempted, the next call will complete without using the MTP transcoding resource. If this call attempted to use the software MTP function to provide supplementary … Continue reading

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RTP timestamp

RTP and RTCP—(Real-Time Transport Protocol and RTP Control Protocol) Protocols used to sequence the audio and video packets. The RTP header contains a time stamp and sequence number, allowing the receiving device to buffer as much as necessary to remove … Continue reading

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call rsvp-sync resv-timer

RSVP is the IP service that allows applications to request end-to-end QoS guarantees from the network. Cisco VoIP applications use RSVP for call admission control, limiting the accepted voice load on the IP network to guarantee the QoS levels of … Continue reading

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Cisco Queuing Methods

First In First Out (FIFO) Queueing First In, First Out (FIFO) Queueing Packets are forwarded in the same order in which they arrive at the interface. Priority Queuing (PQ) PQ ensures that important traffic gets the fastest handling at each … Continue reading

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