Priority queue over ADSL

[iinis]

Hello I have a 3 site VPN over PIXes with a 1721 ADSL router at the main site. I want to prioritise the outgoing VPN traffic over the ordinary internet traffic. I applied a priority list to the dialer but it has no effect on the ATM interface on the router, which is dropping packets.

If I then apply the priority-list to the ATM0 interface, it accepts it but it does not show up in the config and still shows no queuing on that interface.

interface ATM0

no ip address

no atm ilmi-keepalive

pvc 8/35

encapsulation aal5mux ppp dialer

dialer pool-member 2

!

dsl operating-mode auto

hold-queue 224 in

!

interface Dialer2

ip address x.x.x.x 255.255.255.0

no ip redirects

no ip unreachables

encapsulation ppp

dialer pool 2

dialer idle-timeout 100000

dialer-group 2

priority-group 1

ATM0 is up, line protocol is up

Hardware is DSLSAR (with Alcatel ADSL Module)

MTU 4470 bytes, sub MTU 4470, BW 256 Kbit, DLY 8000 usec,

reliability 255/255, txload 7/255, rxload 28/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5 AAL2, PVC mode

23 maximum active VCs, 256 VCs per VP, 2 current VCCs

VC idle disconnect time: 300 seconds

Last input never, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/224/0/0 (size/max/drops/flushes); Total output drops: 11389

Queueing strategy: None

30 second input rate 29000 bits/sec, 8 packets/sec

30 second output rate 8000 bits/sec, 8 packets/sec

3745660 packets input, 2142672726 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

3262040 packets output, 1184269329 bytes, 0 underruns

0 output errors, 0 collisions, 4 interface resets

0 output buffer failures, 0 output buffers swapped out

Dialer2 is up, line protocol is up (spoofing)

Hardware is Unknown

Internet address is x.x.x.x/24

MTU 1500 bytes, BW 56 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, loopback not set

DTR is pulsed for 1 seconds on reset

Interface is bound to Vi1

Last input never, output never, output hang never

Last clearing of "show interface" counters 1w1d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: priority-list 1

Output queue (queue priority: size/max/drops):

high: 0/60/0, medium: 0/40/0, normal: 0/40/0, low: 0/40/0

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

3745675 packets input, 2143111194 bytes

3273443 packets output, 1190746594 bytes

Bound to:

Virtual-Access1 is up, line protocol is up

Hardware is Virtual Access interface

MTU 1500 bytes, BW 56 Kbit, DLY 100000 usec,

reliability 255/255, txload 13/255, rxload 150/255

Encapsulation PPP, loopback not set

DTR is pulsed for 5 seconds on reset

Interface is bound to Di2 (Encapsulation PPP)

LCP Open

Open: IPCP

Bound to ATM0 VCD: 1, VPI: 8, VCI: 35

Cloned from Dialer2

Last input 00:00:00, output never, output hang never

Last clearing of "show interface" counters 1w1d

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

5 minute input rate 33000 bits/sec, 1 packets/sec

5 minute output rate 3000 bits/sec, 1 packets/sec

3745738 packets input, 2143112280 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

3273503 packets output, 1190749180 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

Thanks

Brian T

[gmarogi]

Since the ATM interface is part of dialer pool, I think you will not be allowed to change the queuing on the physical interface. Since you have applied the priority-list to the dialer, you should be looking at the output of 'show int dialer2' which does not show any drops for either of the 4 queues. You can try clearing the counters of the ATM interface and check whether drops are still happening.

[iinis]

Forgot I sent this but I still haven't solved this...

Anyway, the problem IS at the physical interface. The dialer shows no drops because the priority queue is not doing anything for some reason I can't figure out.

The drops ARE the problem. I need to know a strategy for applying QoS to an ADSL interface - any way will do.

Thanks,

Brian T

[lgijssel]

Hi,

We seem to have struck the same issue. The ATM interface only supports FIFO.

According to the Cisco IOS documentation it should be possible to use CBWFQ in this case. Your IOS version must support this feature of course. It is configured as follows:

Router(config)#class-map class-ip

Router(config-cmap)#match protocol ip

Router(config)#class-map class-ipx

Router(config-cmap)#match protocol ipx

Router(config)#policy-map policy-cbwfq

Router(config-pmap)#class class-ip

Router(config-pmap-c)#bandwidth percent 40

Router(config-pmap)#class class-ipx

Router(config-pmap-c)#bandwidth 20

Router(config)#interface atm 0

Router(config-if)#service-policy output policy-cbwfq

The key issue is that you can use a system (IOS) queue behind/before the FIFO queue on the interface.

Try a search for wfq and atm for a doc that explains this matters. Title: Understanding WFQ on ATM.

Regards,

Leo

[imilavec]

Since this is Asymmetric DSL, you should first shape the traffic down to your upload speed. Maybe this document (or links within) can help you:

http://www.cisco.com/en/US/tech/tk175/tk15/technologies_tech_note09186a0080094460.shtml

Regards, Igor