Hi Jaime,


What Egress SFC classifier does if  the pkt has NSH and if SFF is local?



(The slide says it gives is to Ingress SFC Service,  it should be “gives it to 
Ingress Dispatcher” is that correct?)



Regards,

Vinayak



-----Original Message-----
From: Jaime Caamaño Ruiz [mailto:[email protected]]
Sent: Thursday, May 03, 2018 8:07 PM
To: Vinayak Joshi <[email protected]>; [email protected]
Subject: Re: [sfc-dev] Question on OF pipeline



Hello Vinayak



The slide is probably a bit updated.



> Doesn’t this cause a packet loop?



Classifier service index is higher than SFC service index, so this can't happen.

We also set a magic value in NSH C1 on ingress classifier, and egress 
classifier only acts when this magic value is present.



> Isn’t this incorrect, packet with NSH should always be forwarded by

> SFC services?



The packet is intercepted and forwarded by the egress SFC classifier service, 
to the first SFF. Nevertheless, the egress SFC classifier needs to know which 
is the final destination (lport) of the packet, and thats determined by the 
remaining ingress services so thats the reason why the packet is resubmitted to 
the dispatcher by the ingress SFC classifier service.



BR

Jaime.



-----Original Message-----

From: Vinayak Joshi 
<[email protected]<mailto:[email protected]>>

To: [email protected]<mailto:[email protected]> 
<[email protected]<mailto:[email protected]>>, jc 
[email protected]<mailto:[email protected]>

Subject: [sfc-dev] Question on OF pipeline

Date: Thu, 3 May 2018 10:28:00 +0000



Hi,

I have a few questions on the OF pipeline described in Slide 1 at https

://docs.google.com/presentation/d/1gN8GnpVGwku4mp1on7EBZiE41RI7lZ-

FFmFS2QlUTKk/edit#slide=id.g210ac90bb8_0_78.

Sorry for the long mail.

Please point out if the scenarios/my packet flows are incorrect.

Say a regular packet arrives at br-int1 on port P1 from VM1 (i.e. VM1 is not an 
SF).

Say the SFC Classifier (ingress) matches ACL ant it stamps NSH into the packet 
and resubmits to the ingress-dispatcher.

Now there are two possible scenarios:

Port P1 also has SFC service enabled on it.

                                                    i.     Packet gets

into Ingress SFC service which sends the packet to egress dispatcher table.

                                                   ii.     Egress SFC

Classifier acts on it. Since the packet has NSH and if the fist SFF is on the 
same br-int the packet is given packet to Ingress SFC. This is as per-





                                                  iii.     Question:

Doesn’t this cause a packet loop?

Port P1 does not have SFC service enabled on it.

                                                    i.     In this case

a packet with NSH would be given to some other service (say L3) which for 
forward packet to final destination with NSH.

                                                   ii.     Question:

Isn’t this incorrect, packet with NSH should always be forwarded by SFC 
services?

Thanks in advance,

Vinayak

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