cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
118
Views
0
Helpful
0
Replies
Highlighted
Beginner

3560X, MTUs, and ICMP unreachables

Hi!

I'm experiencing an issue on a 3560X (15.0(2)SE10a) that I just can't seem to figure out. The switch is directly connected to a number of Meraki MR32 wireless access points which are set to 'layer 3 roaming mode.' This mode seems to drop the wireless client MTU down to 1448 (probably for tunneling.) Here's the part I don't get: if I send a 1449+ df-bit ping from any directly connected device on the 3560 to any wireless client, here's what I see on the Meraki end:

09:49:57.776240 IP [wireless client's AP IP] > [ping source IP]: ICMP [wireless client IP] unreachable - need to frag (mtu 1448), length 556

These unreachables however never make it to the source sending the pings (even if the source is the 3560 itself.) 'monitor session' confirms that the APs really are sending unreachables, and there are no ACLs on the interfaces being used. 'no ip unreachables' is also not used.

What could cause something like this? Why are the unreachables not making it back to the source? The 3560 seems to just completely drop them.

For reference, each AP on the 3560 has the following configuration:

 switchport trunk encapsulation dot1q
 switchport trunk native vlan n
 switchport trunk allowed vlan n,n,n,n
 switchport mode trunk
 switchport nonegotiate

Any help is appreciated. Thank you!

 

0 REPLIES 0
Content for Community-Ad