Disable default route installed in dpu#24495
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yue-fred-gao wants to merge 2 commits intosonic-net:masterfrom
Closed
Disable default route installed in dpu#24495yue-fred-gao wants to merge 2 commits intosonic-net:masterfrom
yue-fred-gao wants to merge 2 commits intosonic-net:masterfrom
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/azp run Azure.sonic-buildimage |
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Azure Pipelines successfully started running 1 pipeline(s). |
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hi @prsunny and @prabhataravind may we have a reviewer added please? |
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/azp run Azure.sonic-buildimage |
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Azure Pipelines successfully started running 1 pipeline(s). |
Contributor
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@yue-fred-gao I recall this was fixed in the past. See below PRs. You can just remove the gateway config from smartswitch DHCP config and the default route should not get programmed. Could you check that instead of adding a smartswitch specific check? |
prabhataravind
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Nov 15, 2025
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Could we just remove gateway from smartswitch DHCP_SERVER_IPV4 default config?
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Thanks. Let me explore the other option. |
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yxieca
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Dec 15, 2025
gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See #24495 (comment). Signed-off-by: Yue Gao <yuega2@cisco.com>
hdwhdw
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Dec 18, 2025
) gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See sonic-net#24495 (comment). Signed-off-by: Yue Gao <yuega2@cisco.com> Signed-off-by: Dawei Huang <daweihuang@microsoft.com>
xwjiang-ms
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Dec 22, 2025
) gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See sonic-net#24495 (comment). Signed-off-by: Yue Gao <yuega2@cisco.com> Signed-off-by: xiaweijiang <xiaweijiang@microsoft.com>
jasonbridges
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Jan 22, 2026
) gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See sonic-net#24495 (comment). Signed-off-by: Yue Gao <yuega2@cisco.com>
mssonicbld
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Feb 13, 2026
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#### Why I did it
gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See sonic-net#24495 (comment).
if gateway is not set, show dhcp_server ipv4 info failed.
Traceback (most recent call last):
File "/usr/local/bin/show", line 8, in <module>
sys.exit(cli())
^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 764, in __call__
return self.main(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 717, in main
rv = self.invoke(ctx)
^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 956, in invoke
return ctx.invoke(self.callback, **ctx.params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/decorators.py", line 64, in new_func
return ctx.invoke(f, obj, *args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.11/dist-packages/show/plugins/dhcp-server.py", line 113, in info
table.append([interface, entry["mode"], entry["gateway"], entry["netmask"], entry["lease_time"], entry["state"]])
~~~~~^^^^^^^^^^^
KeyError: 'gateway'
##### Work item tracking
- Microsoft ADO **(number only)**:
#### How I did it
If gateway is not present, use empty string instead.
#### How to verify it
run the command when gateway is not present
`
+-----------------+--------+-----------+---------------+-----------------+---------+
| Interface | Mode | Gateway | Netmask | Lease Time(s) | State |
+=================+========+===========+===============+=================+=========+
| bridge-midplane | PORT | | 255.255.255.0 | 600000000 | enabled |
+-----------------+--------+-----------+---------------+-----------------+---------+
`
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mssonicbld
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Feb 13, 2026
<!-- Please make sure you've read and understood our contributing guidelines: https://github.com/Azure/SONiC/blob/gh-pages/CONTRIBUTING.md failure_prs.log Make sure all your commits include a signature generated with `git commit -s` ** If this is a bug fix, make sure your description includes "fixes #xxxx", or "closes #xxxx" or "resolves #xxxx" Please provide the following information: --> #### Why I did it gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See #24495 (comment). if gateway is not set, show dhcp_server ipv4 info failed. Traceback (most recent call last): File "/usr/local/bin/show", line 8, in <module> sys.exit(cli()) ^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 764, in __call__ return self.main(*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 717, in main rv = self.invoke(ctx) ^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1137, in invoke return _process_result(sub_ctx.command.invoke(sub_ctx)) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1137, in invoke return _process_result(sub_ctx.command.invoke(sub_ctx)) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 1137, in invoke return _process_result(sub_ctx.command.invoke(sub_ctx)) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 956, in invoke return ctx.invoke(self.callback, **ctx.params) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 555, in invoke return callback(*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/decorators.py", line 64, in new_func return ctx.invoke(f, obj, *args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/click/core.py", line 555, in invoke return callback(*args, **kwargs) ^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.11/dist-packages/show/plugins/dhcp-server.py", line 113, in info table.append([interface, entry["mode"], entry["gateway"], entry["netmask"], entry["lease_time"], entry["state"]]) ~~~~~^^^^^^^^^^^ KeyError: 'gateway' ##### Work item tracking - Microsoft ADO **(number only)**: #### How I did it If gateway is not present, use empty string instead. #### How to verify it run the command when gateway is not present ` +-----------------+--------+-----------+---------------+-----------------+---------+ | Interface | Mode | Gateway | Netmask | Lease Time(s) | State | +=================+========+===========+===============+=================+=========+ | bridge-midplane | PORT | | 255.255.255.0 | 600000000 | enabled | +-----------------+--------+-----------+---------------+-----------------+---------+ ` <!-- If PR needs to be backported, then the PR must be tested against the base branch and the earliest backport release branch and provide tested image version on these two branches. For example, if the PR is requested for master, 202211 and 202012, then the requester needs to provide test results on master and 202012. --> #### Which release branch to backport (provide reason below if selected) <!-- - Note we only backport fixes to a release branch, *not* features! - Please also provide a reason for the backporting below. - e.g. - [x] 202006 --> - [ ] 202205 - [ ] 202211 - [ ] 202305 - [ ] 202311 - [ ] 202405 - [ ] 202411 - [ ] 202505 #### Tested branch (Please provide the tested image version) master <!-- - Please provide tested image version - e.g. - [x] 20201231.100 --> - [ ] <!-- image version 1 --> - [ ] <!-- image version 2 --> #### Description for the changelog <!-- Write a short (one line) summary that describes the changes in this pull request for inclusion in the changelog: --> <!-- Ensure to add label/tag for the feature raised. example - PR#2174 under sonic-utilities repo. where, Generic Config and Update feature has been labelled as GCU. --> #### Link to config_db schema for YANG module changes <!-- Provide a link to config_db schema for the table for which YANG model is defined Link should point to correct section on https://github.com/Azure/sonic-buildimage/blob/master/src/sonic-yang-models/doc/Configuration.md --> #### A picture of a cute animal (not mandatory but encouraged)
FengPan-Frank
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Mar 6, 2026
) gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See sonic-net#24495 (comment). Signed-off-by: Yue Gao <yuega2@cisco.com> Signed-off-by: Feng Pan <fenpan@microsoft.com>
dprital
pushed a commit
that referenced
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Mar 19, 2026
gateway is optional field. In smartswitch use case, dhcp server runs in the switch and is used to offer addresses to DPU midplane. But we don't want to install default route over the midplane interface so gateway option is removed from DHCP server config. See #24495 (comment). Signed-off-by: Yue Gao <yuega2@cisco.com> Signed-off-by: dprital <drorp@nvidia.com>
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Why I did it
DPU in smartswitch uses dhcp to get ip for its midplane interface. The interface is only for management traffic. Data traffic should go through Ethernet interface, which is where the default route should be. So we should not install a default route by dhcp over the midplane interface. It will disrupt data traffic.
Work item tracking
How I did it
Change dhcp server in smart-switch not to send "routers" option to dhcp client.
How to verify it
Reboot dpu or renew dhcp lease and verify no default route installed into dpu.
Which release branch to backport (provide reason below if selected)
Tested branch (Please provide the tested image version)
Description for the changelog
Link to config_db schema for YANG module changes
A picture of a cute animal (not mandatory but encouraged)