SIP and cisco

[hagjohn]

We are adding SIP to one of our customers and we need to prioritize SIP in our Cisco 7500. Would a config like this work (below)? I would assume we would put this "access-list" on all of our "connections" (WAN, LAN, Serials, etc...) or is there a global way of doing this? We are not running any SIP protocols on the cisco.


interface FastEthernet4/0
ip address 63.xxxx.xxx.xxx 255.255.255.0
ip access-group 105 in
ip access-group 105 out
!
access-list 105 remark VOIP (SIP/IAX/IAX2) traffic gets top priority (5)
access-list 105 permit udp any any eq 4569
access-list 105 permit udp any any eq 5004
access-list 105 permit udp any any eq 5036
access-list 105 permit udp any any eq 5060

 

[lockcole]

Um, im a little confused, SIP is encapulated in IP. At layer 2/3 SIP doesnt enter the format.

I worked at this great ISP years ago, Internode was the bomb.

Simple QoS syntax.

First make an ACL (i wanna mark all upload traffic going out a dialer with a mad priority and the EF bit set). Select the ports and S/D IPs which it relates to.

ip access-list extended QOS-Traffic
permit tcp any any
permit udp any any

Secondly, Create a MAP to link all revelent ACLs to. (this makes lets u mix and match ACLs so ur not forever re-writing the same shit over and over again).

class-map match-all QOS-Map
match access-group name QOS-Traffic

Thirdly, Define what policy is. (this is like what should happen to the map, how it should be policed, remarked, marked, etc etc). Remember CoS is caculated of a binary truth table from the ToS/DSCP fields at layer 3. There is much debate on the net about the correct formular for different types of traffic. My advice is to learn out they work it out and make it work for ur network. In my case i just wanna mark my traffic so it gets a good marking through the WAN (until someone remarks it)

policy-map QOS-Policy
class QOS-Map
set dscp ef
priority 55

And finally, apply the policy to an interface in the 'ONLY' direction it can be applied, on the egress.

interface ATM0
description ATM WIC
no ip address
no atm ilmi-keepalive
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1
!
dsl operating-mode auto
service-policy output QOS-Policy


Hope that helps.


A priority of 5 in DSCP terms is shit. Are u sure its the priority or the CoS vaule of 5? Remember CoS operates at layer 2 and DSCP is at layer 3, CoS has a value of 0-7. Once it routing is performed CoS is completely striped bro

 

[lockcole]

Also, in the example above, all marked traffic will remain the same, but all unmarked traffic will get the above priority and the EF bit set. There is only 1 queue defined and no dropping of packets defined.

Check the theory of 'tail drops' in QoS to understand how and y everyone has there own views.

 

[burtsbees]

Tail drops...that's where WRED comes in, my friend...

Burt