[Dell-S6100]:Buffer_profile is not dynamically changed after changing cable length in config db

[chitra-raghavan]

Description

Upon changing the Cable length for an interface in config db, buffer_profile is not dynamically created and applied to the interface

Steps to reproduce the issue:

1. change cable length for an interface in config db
2. create and apply buffer profiles
3. Check whether the buffer_profiles got changed for the particular port

Describe the results you received:

1. Initial Config :

• Interface : Ethernet1 connected to Spine router
• Localhost : Leafrouter
• Speed : 10000
• Cable length : 300m
• Buffer profile : pg_lossless_10000_300m_profile

127.0.0.1:6379[4]> hget DEVICE_METADATA|localhost type
"LeafRouter"

127.0.0.1:6379[4]> hget PORT|Ethernet1 "speed"
"10000"
127.0.0.1:6379[4]> hgetall "DEVICE_NEIGHBOR|Ethernet1"
1) "name"
2) "ARISTA02T2"
3) "port"
4) "Ethernet1"
127.0.0.1:6379[4]> hget "DEVICE_NEIGHBOR_METADATA|ARISTA02T2" type
"SpineRouter"
127.0.0.1:6379[4]>   hget  "CABLE_LENGTH|AZURE" Ethernet1
"300m"
127.0.0.1:6379[4]>  hgetall  "BUFFER_PG|Ethernet1|3-4"
1) "profile"
2) "[BUFFER_PROFILE|pg_lossless_10000_300m_profile]"

2. Change the neighbor , create buffer.json file and apply

• Now Ethernet1 is conneced to Tor Router
• create Buffer templates and apply to db
• Check Cable _length and buffer profiles. Here the cable length is changed in db t0 40m , but the Buffer_profile is not selected accordingly. it still holds pg_lossless_10000_300m_profile

127.0.0.1:6379[4]> hget "DEVICE_NEIGHBOR_METADATA|ARISTA02T0" type
"ToRRouter"

127.0.0.1:6379[4]>  hset "DEVICE_NEIGHBOR|Ethernet1" "name" "ARISTA02T0"
(integer) 0

 sonic-cfggen -d   -t /usr/share/sonic/device/x86_64-dell_s6100_c2538-r0/Force10-S6100/buffers.json.j2 >/tmp/buffers.json
 sonic-cfggen -j /tmp/buffers.json --write-to-db
 
127.0.0.1:6379[4]>   hget  "CABLE_LENGTH|AZURE" Ethernet1
"40m"
127.0.0.1:6379[4]>  hgetall  "BUFFER_PG|Ethernet1|3-4"
1) "profile"
2) "[BUFFER_PROFILE|pg_lossless_10000_300m_profile]"

3. When there is change in speed , then using new cable length and speed , the buffer profile gets created . Now 40g_40m profile gets selected

127.0.0.1:6379[4]>  hgetall  "PORT|Ethernet1"
1) "speed"
2) "10000"
127.0.0.1:6379[4]> hset "PORT|Ethernet1" "speed" 40000
(integer) 0
127.0.0.1:6379[4]>  hget  "CABLE_LENGTH|AZURE" Ethernet1
"40m"
127.0.0.1:6379[4]>  hgetall  "BUFFER_PG|Ethernet1|3-4"
1) "profile"
2) "[BUFFER_PROFILE|pg_lossless_40000_40m_profile]"
127.0.0.1:6379[4]>

Describe the results you expected:

When there is change in cable length , the buffer_profile should change accordingly , even though speed is not changed

Output of show version:

showroot@sonic-s6100-01:~# show ver
SONiC Software Version: SONiC.HEAD.159-e69ce25
Distribution: Debian 9.4
Kernel: 4.9.0-5-amd64
Build commit: e69ce25
Build date: Sun Apr  1 12:22:17 UTC 2018
Built by: johnar@jenkins-worker-3

Docker images:
REPOSITORY                 TAG                 IMAGE ID            SIZE
docker-syncd-brcm-orig     latest              21deed7a9544        358.2 MB
docker-syncd-brcm          HEAD.159-e69ce25    21deed7a9544        358.2 MB
docker-orchagent-brcm      HEAD.159-e69ce25    4402f3397c62        287 MB
docker-orchagent-brcm      latest              4402f3397c62        287 MB
docker-lldp-sv2            HEAD.159-e69ce25    bd270863a533        297.1 MB
docker-lldp-sv2            latest              bd270863a533        297.1 MB
docker-dhcp-relay          HEAD.159-e69ce25    2c61bc6343b1        280.1 MB
docker-dhcp-relay          latest              2c61bc6343b1        280.1 MB
docker-database            HEAD.159-e69ce25    29a43900455a        278.7 MB
docker-database            latest              29a43900455a        278.7 MB
docker-teamd               HEAD.159-e69ce25    54378e02e9c3        284.1 MB
docker-teamd               latest              54378e02e9c3        284.1 MB
docker-snmp-sv2            HEAD.159-e69ce25    2221dc781ffb        319.2 MB
docker-snmp-sv2            latest              2221dc781ffb        319.2 MB
docker-router-advertiser   HEAD.159-e69ce25    5875de6f3bcb        276.4 MB
docker-router-advertiser   latest              5875de6f3bcb        276.4 MB
docker-platform-monitor    HEAD.159-e69ce25    5a8efa12f3c0        298.3 MB
docker-platform-monitor    latest              5a8efa12f3c0        298.3 MB
docker-fpm-quagga          HEAD.159-e69ce25    d0832f4b4d35        290.6 MB
docker-fpm-quagga          latest              d0832f4b4d35        290.6 MB
docker-syncd-brcm-rpc      1                   727b7c7712b8        581.9 MB
docker-syncd-brcm-rpc      latest              727b7c7712b8        581.9 MB
docker-syncd-brcm          latest              727b7c7712b8        581.9 MB

[xinliu-seattle]

I am contacting Dell to take a look at this issue.

[vharish02]

Chitra,
This is as per design the cable length should not be changed had a chat with Ying of MSFT as well. Ying want's know why do you want to change the cable length. Once installed in the data center the cable length is fixed and does not change.
This is probably not a bug.

[chitra-raghavan]

Thanks Harish. I will close the bug as this is not a requirement.