CCIE Voice Lab - queries

Unanswered Question
Sep 1st, 2008

Hi,

I am preparing for voice lab and coming up with few questions if someone can answer:

1) What default COS-DSCP-MAP needs to be changed when configuring Campus wide QOS? I think only COS 5 needs to be mapped to 46-47 instead of 42-47 even if it is not asked in the Lab.

set qos cos-dscp-map 0 10 18 26 34 46 48 56

Is there any change required in dscp to cos map as well?

set qos dscp-cos-map 0-7:0 8-15:1 16-23:2 24-31:3 32-39:4 40-47:5 48-55:6 56-63:7

2) UniverCD is getting dicontinued. Does someone know exactly what Cisco documentation (URL) would be available in place of UniverCD and what'll be the restrictions to access the same?

3) If codec sampling rate needs to be changed on H.323 GW (for ex for G.729 from 20ms to 30 ms), should we change only at GW level and CCM will negotiate or both sides need to be changed? How about MGCP Gateway?

4) Do we need to enable spanning-tree portfast on Cat6k port connecting to IP Phones? Say Lab exam doesn't mention but about enabling spanning-tree portfast but it does ask to configure data and voice vlan on IP Phone ports.

5) When using 6608-T1 or E1 with CAS, how can we configure it to use only first three time-slots? Is this done the same way as done for fractional PRI by configuring service parameters or by configuring only 1-3 ports for incoming/outgoing/both directions under MGCP gateway config?

6) When 6608-T1/E1 is configured for CAS, does the lab mention which type of signaling needs to be configured per timeslot for ex. wink-start,delay-start etc. or leave it default to wink-start?

6) In case of H.323 GW, if default channel-selection-order needs to be changed from bottom up to top down, is this need to be changed under isdn interface only or at CCM Gateway confiugration page as well?

Thanks,

inner_silence

I have this problem too.
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Ayodeji oladipo... Mon, 09/01/2008 - 05:04

Hi,

I can answer a few of your questions.

1. You do not need to map DSCP-COS..Swithes use COS not dscp hence the need to map incoming dscps to cos for the switches to understand and treat as configured.

3. Codec sampling rate should only be changed on CCM> once this is done, the new rate will take effect. I have done this a few times.

6. Most importantly, you need to change the channel selection order from the gateway. CCM will also use bottom up, regardless of what you change it to, hence you need to m ake the change on the GW for the desired effect.

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