[c-nsp] QoS on Multilink T1's.

[Lee]

On 4/3/12, Joseph Mays <mays at win.net> wrote:
>> I took each t1 individually out of the multilink bundle, so the bundle
>> contained only the first t1, then only the second t1. In both cases, the
>> problem disappeared and QoS began working normally as soon as there was
>> only one t1 in the bundle. This is without changing the multilink
>> interface config or policy itself. As soon as I put both t1's back in the
>> problem returns immediately.
>>
>> Right now I'm planning to upgrade the router to 12.4ish Monday.
>
> So unfortunately this problem still exists. If upgrading from 12.3 to 12.4
> did not fix the problem, I guess it's probably not a bug. So I'm momentarily
> at a loss. I can post the config if anyone would like to see it. Is there
> anyone out there who is doing QoS across a multilinked bundle of more than
> one T1 who can send it to me so I can compare what you have with what I am
> doing?

Are they real T1s or are they 1.5Mb MPLS service?  We've got several
4xT1 (MPLS service) bundles working & had to pay for QOS to get voice
working acceptably well.

class-map match-any voice-control
 match ip dscp af31
 match ip dscp cs3
class-map match-any video
 match ip dscp af41
class-map match-any voice
 match ip dscp ef
!
policy-map 6m-wan
 class voice
    priority 1172
 class voice-control
    bandwidth 100
 class video
    bandwidth 2500
 class class-default
    fair-queue
     random-detect dscp-based

interface Multilink1
 mtu 1700
 bandwidth 6144
 ip address a.d.d.r  m.a.s.k
 no cdp enable
 ppp multilink
 ppp multilink group 1
 crypto map foo
 service-policy output 6m-wan

interface Serial0/0/0 thru 0/1/1
 mtu 1700
 no ip address
 encapsulation ppp
 no cdp enable
 ppp multilink
 ppp multilink group 1

The tunnel interface has "qos pre-classify" but no service policy.

I have a vague memory of having to do "no fair-queue" on all of the
serial interfaces.  If you try that, make sure the serial interfaces
are down first.

Hope this helps,
Lee