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Webcast-Catalyst9k
New Member

Strange issue between AP and switch

Hi Guys,

I have encountered a weird fix to a problem that I would like to get some clarity on. Basically, we have a Cisco 1600 AP, connecting directly to a Layer 3 switch. The data VLAN (and therefore the VLAN the AP's are in) are VLAN 4. There is a Voice VLAN of 5 and a Transit VLAN of 255.

The problem I was encountering is that I can only access the AP from VLAN 5 and no other VLAN. Now my first thoughts would be the default gateway, but as you can see in the config it is correct. A Ping from VLAN 5 on the switch works but from VLAN 4 doesn't. Other connectivity like from the AP to the DC, doesn't reach the default gateway and connectivity from the DC to the AP only reaches the switch.

SW-01#ping 172.16.34.11 source vlan 5

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.34.10, timeout is 2 seconds:

Packet sent with a source address of 172.16.68.1

.....                                                                                //UNSUCCESSFUL

Success rate is 0 percent (0/5)

SW-01#ping 172.16.34.11 sou vlan 4

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.34.11, timeout is 2 seconds:

Packet sent with a source address of 172.16.34.1

!!!!!                                                                                     //SUCCESSFUL

Success rate is 100 percent (5/5),

When I trace to the default-way it reaches there in one hop. But when I trace to a point beyond the default-gateway it doesn't even reach the first hop i.e. the default-gateway.

NOW THE FIX:

The command that fixed this is:

ip route 0.0.0.0 0.0.0.0 172.16.34.1

PLEASE explain why this would of fixed the problem. I don't see why I would need to add a route on a Layer 2 device. Surely, the default-gateway command allows it to find its way out of the network.

I have attached the configuration of the switch and AP.

Thanks

Grant

1 ACCEPTED SOLUTION

Accepted Solutions
Bronze

Re: Strange issue between AP and switch

Have you recently upgraded AP IOS to Release 15.2(2)JB?

"IP routing is enabled by default in 15.2(2)JB. This default configuration will render ip default-gateway statements inoperable. The work around is to disable ip routing globally (config t, no ip routing), or configure a default route instead of a default-gateway (e.g. config t, ip route 0.0.0.0 0.0.0.0 )."

Please see Release Notes:

http://www.cisco.com/en/US/docs/wireless/access_point/ios/release/notes/15.2_2_JB.html#wp357790

3 REPLIES
Bronze

Re: Strange issue between AP and switch

Have you recently upgraded AP IOS to Release 15.2(2)JB?

"IP routing is enabled by default in 15.2(2)JB. This default configuration will render ip default-gateway statements inoperable. The work around is to disable ip routing globally (config t, no ip routing), or configure a default route instead of a default-gateway (e.g. config t, ip route 0.0.0.0 0.0.0.0 )."

Please see Release Notes:

http://www.cisco.com/en/US/docs/wireless/access_point/ios/release/notes/15.2_2_JB.html#wp357790

New Member

Re: Strange issue between AP and switch

Hi aukhadiev,

That answers my question exactly. Thank you so much for the prompt response!

Cheers

Grant

Cisco Employee

Strange issue between AP and switch

Hi,

Good catch! Rated as deserved.

Best regards,

Peter

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