Extend show ip route nexthop-group commands (Summary view and ECMP filtering) #19833

raja-rajasekar · 2025-10-23T21:20:47Z

Extend show ip route nexthop-group commands

show ip route nexthop-group summary
show ip route nexthop-group summary ecmp-count gt N (greater than)
show ip route nexthop-group summary ecmp-count lt N (less than)
show ip route nexthop-group summary ecmp-count eq N (equal to)

ton31337

Could you add a topotest showing that it works?

raja-rajasekar · 2025-10-27T17:11:23Z

Could you add a topotest showing that it works?

will do

mjstapp

can you say some more about the motivation for this? is there information here that couldn't be extracted from existing json output? what's the use-case you anticipate: it seems like any "summary" that potentially includes a large number of prefixes is not going to be very useful at scale?

raja-rajasekar · 2025-10-27T21:24:03Z

can you say some more about the motivation for this? is there information here that couldn't be extracted from existing json output? what's the use-case you anticipate: it seems like any "summary" that potentially includes a large number of prefixes is not going to be very useful at scale?

Given that we are going to support higher ECMP, what I see is

Show ip route nexthop-group shows nexthops information as well.
- So, imagine 1K routes via 128 ECMP, the output floods before we can move on to the next route. Same in case of JSON (we have 128 Nexthop information)
- The idea here is to show the ip route without the nexthops (json/non json).
Easier to have an option to display routes with ECMP count < 10 or >32 etc...

Majorly, JSON output is not huge with this fix in this case, as compared to the existing. (so memory/BGP MAIN CPU would benefit).

But again, this is my opinion. Let me know if you have some inputs as well, so that we scrap this idea/make this better.

ton31337

Could you use a consistent nexthop description for the JSON fields?

Now we have:

internalNextHopNum
installedNexthopGroupId
nexthopGroupId

nexthop keyword has a mixed variation...

ton31337 · 2025-10-28T07:25:00Z

zebra/zebra_vty.c

+			if (re->nhe) {
+				json_object_int_add(json_route, "nexthopGroupFlags",
+						    re->nhe->flags);
+				json_object_string_add(json_route, "nexthopGroupValid",


Use json_object_boolean_add().

ton31337 · 2025-10-28T07:26:15Z

zebra/zebra_vty.c

+				json_object_boolean_true_add(json_route, "offloaded");
+
+			if (CHECK_FLAG(re->flags, ZEBRA_FLAG_OFFLOAD_FAILED))
+				json_object_boolean_false_add(json_route, "offloaded");


Does it just overwrite the previous one?

yes, same used to happen before as well.

if (CHECK_FLAG(re->flags, ZEBRA_FLAG_OFFLOADED)) json_object_boolean_true_add(json_route, "offloaded"); if (CHECK_FLAG(re->flags, ZEBRA_FLAG_OFFLOAD_FAILED)) json_object_boolean_false_add(json_route, "offloaded");

i think idea is to set offloaded correctly.

mjstapp · 2025-10-28T13:28:47Z

some comments:

  * So, imagine 1K routes via 128 ECMP, the output floods before we can move on to the next route.  Same in case of JSON (we have 128 Nexthop information)
  * The idea here is to show the ip route without the nexthops (json/non json).

but ... while it's true that 128K lines is more than 1K lines, 1K lines is still probably not very useful for a human to read? in other words, it doesn't take much scale to make vanilla ascii output ... not very useful. And for any system-level orchestration or controller, the output really has got to be json, to make the output machine-parseable. and if the output is parsed into python objects (for example), then it can be searched, sorted, filtered, etc in many ways, not just one way?

I don't know - I just think we have a lot of knob-turning in the vty output code, and I worry a bit about adding more and more, for maintainability.

Previously, the json and nexthop-group options were mutually exclusive in the show ip/ipv6 route commands. As of now, sh ip route json or sh ip route nexthop-group json shows same output. This commit is to be used by future new summary command. Signed-off-by: Rajasekar Raja <[email protected]>

Add a utility function to format nexthop group flags into a comma-separated string for display. This allows consistent flag formatting across different commands. Signed-off-by: Rajasekar Raja <[email protected]>

Use dump_nhg_flags for text output in show nexthop-group command. Signed-off-by: Rajasekar Raja <[email protected]>

raja-rajasekar · 2025-11-03T23:13:14Z

Could you use a consistent nexthop description for the JSON fields?

Now we have:

internalNextHopNum installedNexthopGroupId nexthopGroupId

nexthop keyword has a mixed variation...

@ton31337
Are you asking me to make nexthopGroupID as NextHopGroupId (Capital Letters) (or) something else? Could you please clarify

Add support for 'show ip route nexthop-group summary' command to display a concise view of routes with ECMP counts instead of listing all nexthops. The existing 'show ip route nexthop-group' command displays all nexthop details for each route, which can be verbose and difficult to review when dealing with many ECMP paths. Example: sh ip route vrf vrf-101 nexthop-group B>* 10.0.101.1/32 [200/0] (39) via 192.168.1.1, bridge-101 onlink, weight 1, 03:11:12 via 192.168.1.1, bridge-101 onlink (dup), weight 1, 03:11:12 sh ip route vrf vrf-101 bgp nexthop-group B>* 10.0.101.1/32 [200/0] (39) via 192.168.1.1, bridge-101 onlink, weight 1, 00:03:15 via 192.168.1.1, bridge-101 onlink (dup), weight 1, 00:03:15 The new 'summary' option provides a single-line view per prefix showing: - Received/Installed NHG IDs - ECMP count and FIB installed count - Route entry status - Nexthop group flags Example: sh ip route vrf vrf-101 nexthop-group summary B>* 10.0.101.1/32 [200/0] Rcv/Ins NHG: 39/39 ECMP/FIB count: 2/1 Status: installed Flags: Valid, Installed sh ip route vrf vrf-101 bgp nexthop-group summary B>* 10.0.101.1/32 [200/0] Rcv/Ins NHG ID: 39/39 ECMP/FIB count: 2/1 Status: Installed Flags: Valid, Installed This makes it easier to quickly assess ECMP path counts across multiple routes. Signed-off-by: Rajasekar Raja <[email protected]>

Add support for filtering routes by ECMP count in the nexthop-group summary command. The new syntax allows filtering routes based on ECMP count: - show ip route nexthop-group summary ecmp-count gt N (greater than) - show ip route nexthop-group summary ecmp-count lt N (less than) - show ip route nexthop-group summary ecmp-count eq N (equal to) and their corresponding json Example: r1# sh ip route sharp nexthop-group summary ecmp-count eq 2 D> 2.2.2.1/32 [150/0] Rcv/Ins NHG ID: 90/90 ECMP/FIB count: 2/2 Status: Installed Flags: Valid, Installed D>* 2.2.2.2/32 [150/0] Rcv/Ins NHG ID: 109/109 ECMP/FIB count: 2/2 Status: Installed Flags: Valid, Installed D> 3.3.3.2/32 [150/0] Rcv/Ins NHG ID: 118/118 ECMP/FIB count: 2/1 Status: Installed Flags: Valid, Installed D> 5.5.5.1/32 [150/0] Rcv/Ins NHG ID: 152/152 ECMP/FIB count: 2/8 Status: Installed Flags: Valid, Installed r1# sh ip route sharp nexthop-group summary ecmp-count lt 2 D> 3.3.3.1/32 [150/0] Rcv/Ins NHG ID: 111/112 ECMP/FIB count: 1/2 Status: Installed Flags: Valid, Recursive r1# sh ip route sharp nexthop-group summary ecmp-count eq 1 json {"3.3.3.1/32":[{"prefix":"3.3.3.1/32","prefixLen":32,"protocol":"sharp", "vrfId":0,"vrfName":"default","selected":true,"destSelected":true, "distance":150,"metric":0,"installed":true,"table":254, "nexthopGroupId":113,"ecmpCount":1,"fibInstalledCount":2, "installedNexthopGroupId":114,"receivedNexthopGroupId":113, "nexthopGroupFlags":9,"nexthopGroupValid":"true"}] } Signed-off-by: Rajasekar Raja <[email protected]>

Documentation for nexthop-group summary and ECMP filtering in show ip route nexthop-group cmd Signed-off-by: Rajasekar Raja <[email protected]>

Add test coverage for 'show ip route nexthop-group summary' command with various filters (ecmp-count, protocol, vrf) Signed-off-by: Rajasekar Raja <[email protected]>

mjstapp · 2025-11-04T17:08:34Z

I think he meant the word "nexthop" specifically, there are three different forms in there
maybe "nexthop" when it's the first token (since camel-case), and "Nexthop" otherwise would be ok?

Could you use a consistent nexthop description for the JSON fields?
Now we have:
internalNextHopNum installedNexthopGroupId nexthopGroupId
nexthop keyword has a mixed variation...

@ton31337 Are you asking me to make nexthopGroupID as NextHopGroupId (Capital Letters) (or) something else? Could you please clarify

mjstapp

I'm ok with this

raja-rajasekar · 2025-11-05T15:00:33Z

ci:rerun

frrbot bot added documentation zebra labels Oct 23, 2025

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raja-rajasekar force-pushed the rajasekarr/new_nhg_cmds branch from 35d3c35 to 732331e Compare October 23, 2025 23:41

ton31337 reviewed Oct 24, 2025

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mjstapp reviewed Oct 27, 2025

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raja-rajasekar force-pushed the rajasekarr/new_nhg_cmds branch from 732331e to d0321f8 Compare October 27, 2025 22:40

github-actions bot added size/XXL and removed size/XL labels Oct 27, 2025

raja-rajasekar requested review from mjstapp and ton31337 October 28, 2025 04:22

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raja-rajasekar added 3 commits November 3, 2025 14:55

zebra: Add dump_nhg_flags() helper function

2d950bd

Add a utility function to format nexthop group flags into a comma-separated string for display. This allows consistent flag formatting across different commands. Signed-off-by: Rajasekar Raja <[email protected]>

zebra: Refactor show NHG flags display

9cf3fca

Use dump_nhg_flags for text output in show nexthop-group command. Signed-off-by: Rajasekar Raja <[email protected]>

raja-rajasekar force-pushed the rajasekarr/new_nhg_cmds branch 2 times, most recently from 3a1da2e to 1e1ad65 Compare November 3, 2025 23:33

raja-rajasekar added 4 commits November 3, 2025 16:58

doc: Add documentation for nexthop-group summary and ECMP filtering

b191fd8

Documentation for nexthop-group summary and ECMP filtering in show ip route nexthop-group cmd Signed-off-by: Rajasekar Raja <[email protected]>

topotests: Add nexthop-group summary cmd tests

ef3e77b

Add test coverage for 'show ip route nexthop-group summary' command with various filters (ecmp-count, protocol, vrf) Signed-off-by: Rajasekar Raja <[email protected]>

raja-rajasekar force-pushed the rajasekarr/new_nhg_cmds branch from 1e1ad65 to ef3e77b Compare November 4, 2025 01:02

raja-rajasekar requested a review from ton31337 November 4, 2025 01:02

mjstapp approved these changes Nov 4, 2025

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Extend show ip route nexthop-group commands (Summary view and ECMP filtering) #19833

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Extend show ip route nexthop-group commands (Summary view and ECMP filtering) #19833

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