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QoS with Ephemeral port

cecilmayy
Level 1
Level 1

If my ACL for QoS is: example

 

ip access-list extended SET-AF41

 remark High Pri

 permit tcp any any eq 80

 

class-map xxxx match access-list extended SET-AF41

set af41

 

1. TCP Ephemeral Source Port 32222, Destination Port 80. Matches the ACL and MARKED packet as AF41

2. Return Packet is destination port 32222

3 How does the returning router knows that the returning packet should be marked AF41?

Note: ignore some of the commands - Just looking for the concept on how the returning router keeps track of QoS returning packet DSCP value.  

5 Replies 5

Jon Marshall
Hall of Fame
Hall of Fame

 

As far as I know it doesn't ie. QOS is not stateful and the router does not keep track of connections in the way a firewall would. 

 

If you want QOS on the return path you would need configure that as well.

 

Jon

Jon,

 

I don't think this ACL will make any difference,  Maybe NBAR will or a different ACL with source IP and destination without ports numbers on both ends. Although it will be wide open.  

 

ip access-list extended SET-AF41

 remark High Pri

 permit tcp any any www

 

 

 

I don't really understand what you are saying. 

 

As I said if you want QOS for the return path you need to configure it. 

 

Jon

Thanks for your time, Jon.

 

What I meant to say is that its difficult to craft and return Http/https return packet ACL because the return packet will have random ports as it destination ports (1024–65535)

 

ip access-list extended SET-AF41

 remark High Pri

30 permit tcp host Server_IP_address  host Client IP_Address range 1024–65535 (something like this on return RTR) Not sure if it's scalable. I got the concept.

 

Thank you,

Jon 

Joseph W. Doherty
Hall of Fame
Hall of Fame

"3 How does the returning router knows that the returning packet should be marked AF41?"

ip access-list extended SET-AF41

remark High Pri

permit tcp any any eq 80
permit tcp any eq 80 any !normally, return http traffic would have 80 as source port

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