From: Nick Griffin (ngriffin@sio.midco.net)
Date: Sat Jan 21 2006 - 14:43:24 GMT-3
Here's a real world one, that I think probably applies to qos in the
lab. I'm looking to get some second opinions on the configuration listed
below.
Basically the Setup is a central site and a remote site connected my an
MPLS cloud. There is EBGP peering between the customer edge, and the
provider. The provider is offering a qos packages that states the
CDR/CIR will be 512K, with 80% of the 512K reserved for real time
traffic, traffic leaving the Customer router must have the appropriate
DSCP/Precedence values intact when traffic enters the mpls cloud. The
problem that I am experiencing is unacceptable rtp/call quality when a
couple larger file transfers are initiated from the remote site, pulling
data from the central to the remote location. The physical access rate
of both circuits is a T1. Things that I am noticing are high levels of
jitter reported on the phones, in addition to what appears to be some
packet loss.
Question 1: the problem appears to begin when there gets to be around
900K of traffic on the serial interface. The show policy map on the
interface doesn't show any drops in the priority queue, packets are
being matched, and there is an offered rate. Is the delay being
experienced being caused by large data packets in the output queue, and
I should work with the provider to enable MLPPP with LFI? If so, how
should be interleaving be set in this type of service, should I be
basing my fragmentation size off of the lowest CIR in the cloud, or off
of the physical access rate. I guess based on everything I read I
wouldn't think that LFI on this interface would be required, since
serialization delay shouldn't be an major concern under above 768.
Question 2: it appears that 28XX platform defaults with a tx-ring-limit
value of 128, I have tried changing it to 3, but I didn't see much of a
difference, any recommendations in regards to how this should be set.
Ideally a smaller tx queue should reduce delay, but at the increase tail
drops.
Question 3: When I first started doing some research on FRTS and FRF.12,
there was talk of a DUAL FIFO queue being enabled, which you could see
from a show interface ser0/blah, however some reseach documentation I
found on Cisco says that this is no longer the case. Can anyone confirm?
Sorry for the long email, and any thoughts/recommendations are greatly
appreciated!
class-map match-any bearer
match access-group name VoIP
class-map match-any control
match access-group name Control
class-map match-all default
!
!
policy-map MPLS-Voice
class bearer
set dscp ef
priority 392
class control
set dscp af31
bandwidth 8
queue-limit 512
class class-default
set dscp default
!
interface Serial1/0:0
no ip address
ip nbar protocol-discovery
encapsulation frame-relay
ip route-cache flow
load-interval 30
no fair-queue
frame-relay traffic-shaping
!
interface Serial1/0:0.912 point-to-point
description DLCI 912 for EPVC Circuit ID: DHEC980474
ip address 192.168.249.9 255.255.255.252
frame-relay interface-dlci 912 IETF
class MPLS-Shaping
!
ip access-list extended Control
permit tcp any range 2000 2002 any
remark SCCP
permit tcp any any range 2000 2002
remark H323 Slow Start
permit tcp any any range 11000 11999
remark H323 MGCP
permit udp any any eq 2427
permit tcp any eq 1720 any
permit tcp any eq 1719 any
permit tcp any any eq 1720
permit tcp any any eq 1719
ip access-list extended VoIP
permit ip host 10.34.0.15 any dscp ef
permit udp host 10.34.0.15 any range 16384 32767
permit ip any any dscp ef
permit udp any any range 16384 32767
permit udp any range 16384 32767 any
permit ip any any precedence critical
permit icmp any host 172.30.70.240
!
!
map-class frame-relay MPLS-Shaping
frame-relay cir 1536000
frame-relay bc 15360
frame-relay be 0
frame-relay mincir 1536000
service-policy output MPLS-Voice
wc-br1#sh frame-relay pvc 912
PVC Statistics for interface Serial1/0:0 (Frame Relay DTE)
DLCI = 912, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE =
Serial1/0:0.912
input pkts 191249262 output pkts 240144955 in bytes 2818077992
out bytes 1483472553 dropped pkts 0 in pkts dropped 0
out pkts dropped 0 out bytes dropped 0
in FECN pkts 0 in BECN pkts 0 out FECN pkts 0
out BECN pkts 0 in DE pkts 0 out DE pkts 0
out bcast pkts 50195 out bcast bytes 17332184
5 minute input rate 244000 bits/sec, 105 packets/sec
5 minute output rate 287000 bits/sec, 102 packets/sec
pvc create time 4w6d, last time pvc status changed 4d10h
cir 1460000 bc 14600 be 0 byte limit 1825 interval 10
mincir 1460000 byte increment 1825 Adaptive Shaping none
pkts 120186 bytes 19556954 pkts delayed 62 bytes delayed
24062
shaping inactive
traffic shaping drops 0
service policy MPLS-Voice
Serial1/0:0.912: DLCI 912 -
Service-policy output: MPLS-Voice
Class-map: bearer (match-any)
116964273 packets, 7673643044 bytes
30 second offered rate 9000 bps, drop rate 0 bps
Match: access-group name VoIP
9379664 packets, 614783560 bytes
30 second rate 9000 bps
QoS Set
dscp ef
Packets marked 116964276
Queueing
Strict Priority
Output Queue: Conversation 72
Bandwidth 392 (kbps) Burst 9800 (Bytes)
(pkts matched/bytes matched) 0/0
(total drops/bytes drops) 0/0
Class-map: control (match-any)
3431603 packets, 218501882 bytes
30 second offered rate 2000 bps, drop rate 0 bps
Match: access-group name Control
3431603 packets, 218501882 bytes
30 second rate 2000 bps
QoS Set
dscp af31
Packets marked 3431612
Queueing
Output Queue: Conversation 73
Bandwidth 8 (kbps) Max Threshold 512 (packets)
(pkts matched/bytes matched) 0/0
(depth/total drops/no-buffer drops) 0/0/0
Class-map: class-default (match-any)
119749082 packets, 36541003385 bytes
30 second offered rate 115000 bps, drop rate 0 bps
Match: any
QoS Set
dscp default
Packets marked 119699145
Output queue size 0/max total 600/drops 0
* Serial1/0:0.912 - - - - - - - - -
NOTE:No separate counters are maintained for subinterfaces
Hence Details of subinterface are not shown
r28yanSD01wc-br1#sh int ser 1/0:0 summary
*: interface is up
IHQ: pkts in input hold queue IQD: pkts dropped from input queue
OHQ: pkts in output hold queue OQD: pkts dropped from output queue
RXBS: rx rate (bits/sec) RXPS: rx rate (pkts/sec)
TXBS: tx rate (bits/sec) TXPS: tx rate (pkts/sec)
TRTL: throttle count
Interface IHQ IQD OHQ OQD RXBS RXPS TXBS TXPS TRTL
------------------------------------------------------------------------
* Serial1/0:0 0 0 26 14578 225000 131 937000 157
0
* Serial1/0:0.912 - - - - - - - - -
NOTE:No separate counters are maintained for subinterfaces
Hence Details of subinterface are not shown
r28yanSD01wc-br1#sh int ser 1/0:0 summary
*: interface is up
IHQ: pkts in input hold queue IQD: pkts dropped from input queue
OHQ: pkts in output hold queue OQD: pkts dropped from output queue
RXBS: rx rate (bits/sec) RXPS: rx rate (pkts/sec)
TXBS: tx rate (bits/sec) TXPS: tx rate (pkts/sec)
TRTL: throttle count
Interface IHQ IQD OHQ OQD RXBS RXPS TXBS TXPS TRTL
------------------------------------------------------------------------
* Serial1/0:0 0 0 13 14587 225000 131 937000 157
0
* Serial1/0:0.912 - - - - - - - - -
NOTE:No separate counters are maintained for subinterfaces
Hence Details of subinterface are not shown
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