Re: Segment Routing in ONOS

[Charles Chan]

(+trellis-dev)

1. If the topology is the same, the tree construction should have the same result. What is the purpose of having it updated more frequently? Are you trying to come up with a new path computation algorithm?
Please note that this is not a supported feature and it will require code change. DefaultRoutingHandler should be the place to look at.

2. The article you referred to is very old. You can find a more updated version here: https://github.com/opennetworkinglab/routing/tree/master/trellis
The latest documentation about Trellis can be found here: https://docs.trellisfabric.org/

Thanks,
Charles

On Tuesday, September 24, 2019 at 7:10:28 AM UTC-7, tongva...@gmail.com wrote:

Hi all,

I am studying segment routing for one small project. When I read the source code of segment routing (SR) application in onos, I have some questions.

1. SR application creates the BFS (Breadth-first search) Tree and uses it to identify the routing paths using DFS (Depth-first search) algorithm. If there is any changes related to the configuration, topology and route-added event, SR application will update the BFS Tree to identify the new routing paths.

Is there any ways to force SR application update the BFS Tree more frequently? (I want to change the DFS algorithm and update the routing paths more frequently).

2. I followed the instructions to test the SR application, and I found out some weird. I can use iperf or hping3 to send the packets between 2 hosts, but I cannot replay a pcap file between them (to simulate the traffic of some applications).

Any body know why?

Thank you in advance.

[Sreenivasulu Saya]

  Hi Charles,

> The latest documentation about Trellis can be found here: https://docs.trellisfabric.org/

The Trellis documentation in the above link appears to be much better than that I found in other places.

I have one request...

If the use-case based installation instructions are provided in the documentation, then it will be easy for the first timers to get started quickly with ONOS+Trellis. 

Let us take my experience as an example....

I struggled to get the ONOS+Trellis+P4Runtime with Mininet working for the past seven weeks, but finally gave up out of disappointment/frustration as I could not make much progress! If the developers like me face challenges to work with Trellis, then there will be less traction for the project in the developers community.

Hence, the get the developers interested, using Trellis for the use-cases should be made easy. I think providing the step-by-step instructions for the Trellis uses cases will make huge difference in getting the traction...

Regards,
  --Sreeni Saya

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[Charles Chan]

Could it be an MTU issue? What's the packet size in the pcap?

Thanks,
Charles

On Wednesday, October 2, 2019 at 9:08:59 AM UTC-7, Van Tong wrote:

Hi Charles,

I implemented the updated version, but the second problem still remains. I can use hping3 to send the packets between 2 hosts while I cannot replay a pcap file between them.

I tried with the reactive forwarding application in ONOS, and I can replay the QUIC traffic. Do you know why?

Vào 23:01:05 UTC+2 Thứ Sáu, ngày 27 tháng 9 năm 2019, Charles Chan đã viết:

[Charles Chan]

Hi Van,

At this point my only suggestion is checking the following first

1. Identify at which hop the packets get dropped
2. Check flows and groups. Make sure the packets hit the expected entries.

Also, reactive forwarding is L2 forwarding app while SR is L3 routing app. Maybe it is worth checking your gateway/nexthop in the packet in pcap.

Thanks,

Charles Chan, Ph.D.

Member of Technical Staff, Open Networking Foundation

On Tue, Oct 15, 2019 at 12:39 AM Van Tong <tongva...@gmail.com> wrote:

Hi Charles,

The packet size in the pcap file is 1392. I modified the MTU, but it does not work.

Best regards,

Van

Vào 18:48:39 UTC+2 Thứ Hai, ngày 14 tháng 10 năm 2019, Charles Chan đã viết:

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