Issues with disabling routing on Cisco 3850

[David Kleberson]

I have a Cisco 3850 which runs IOS XE and the issue is that when I'm disabling routing with no ip routing command and configure management SVI with ip default-gateway the switch still shows in the output of show ip route connected and static routes.

I expect not to see this output. To be honest this is my first experience with IOS XE so maybe I'm missing something. Any help is appreciated.

David

[Aninda Chatterjee · Accepted solution]

Hi,

What you're seeing is with ip routing disabled - we moved to something called 'extended host mode' when IP routing is disabled. Due to this, the IP route table does appear to look like how it would when IP routing is enabled.

There is a fairly recent defect filed internally to make this output more friendly (basically tell you if IP routing is disabled or not) so that customers do not get thrown of when they see a routing table even though IP routing is disabled.

Note: IP routing is indeed disabled even though you see the output of the routing table like that. The switch will not route packets.

Regards,

Aninda

[mustafa83]

Hello Aninda,

Is this a bug that will be fixed in later releases or meant to be that way?

also I noticed the same behavior on 3650 running IOS-XE but not on the 4510E with Sup8 running IOS-XE.

Thanks

Mustafa

[emcclend]

Is this still an ongoing issue?  I just installed a 3650 and 3850 and have noticed the same thing.  When the no ip routing command is issued, the show ip routing command will still display the routing table.  Even in the running config, nothing indicates that routing is disabled.

[donnelr]

Has anyone found a way to tell without looking at the routing table?

Cisco IOS XE Software, Version 16.06.08
WS-C3850-24P

[David Kleberson]

Dear Aninda,

Thank you for this explanation! You have clarified this issue for me!

David

[donnelr]

If anyone comes across this, I have a workaround. I verify by using CDP on an adjacent device. Wireshark on a host would also work.

Routing Enabled:

#show cdp neigh
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone, 
                  D - Remote, C - CVTA, M - Two-port Mac Relay 

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
C3850.example.com
                 Gig 2/0/3         139             R S I  WS-C3850- Gig 1/0/3

Routing disabled:

show cdp neigh
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone, 
                  D - Remote, C - CVTA, M - Two-port Mac Relay 

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
C3850.example.com
                 Gig 2/0/3         150              S I   WS-C3850- Gig 1/0/3