[c-nsp] QoS & DSCP bits through a cisco router

[Matthew Crocker]

Hello,

  I'm having a bit of trouble with some QoS on my network

The network looks like

SBC1 -> S1 -> S2 -> R1 -> S3 -> DSLAM -> R2 -> S4 -> IP Phone

SBC1 = Tekelec T6000 soft switch session border controller
S1,S2,S3 are Cisco 3550-12G
R1 is a Cisco 12008 (GRP-B, GE-GBIC-B)
R2 is a netopia (customer router)
S4 is a Linksys (customer switch)
IP Phone is a linksys

S1,S2,S3 are all set to trust the DSCP bits on the proper ports
interface GigabitEthernet0/1
description Link to GSR8-1
switchport trunk encapsulation dot1q
switchport mode trunk
mls qos trust dscp
!

packets coming from the SBC have proper DSCP settings until they pass  
through R1 which sets them to default (0)
packets coming from the IP Phone have proper DSCP settings until they  
pass through R1 as well.

How can I get R1 to preserve the DSCP bits on packets entering in  
from my private network?
i.e.  How do I tell the GSR to trust the traffic coming from G0/0 &  
G5/0 (my internal switches) but not from G4/0 (my GigE Sprint  
connection) ?

What queuing options do I have on the Engine 0 line cards?

The primary bottle neck is the DSLAM -> R2 link (T1) everything else  
is GigE.  If I can preserve the DSCP bits set by the SBC through my  
network the DSLAM can queue the traffic going to the customer.

--
Matthew S. Crocker
President
Crocker Communications, Inc.
Internet Division
PO BOX 710
Greenfield, MA 01302-0710
http://www.crocker.com