LTM returns mgmt traffic with no routes configured

Hi,

 

 

I have an odd issue where I have no MGMT or TMM routes manually configured, yet I am still able to connect to BIGIP from non-directly connected VLANs.

 

 

[admin@BIGIP:Active] ~ b mgmt route show

 

No management interface routes were found.

 

[admin@BIGIP:Active] ~

 

[admin@BIGIP:Active] ~ route

 

Kernel IP routing table

 

Destination Gateway Genmask Flags Metric Ref Use Iface

 

10.10.10.128 * 255.255.255.192 U 0 0 0 vlan10

 

10.10.20.128 * 255.255.255.192 U 0 0 0 eth0

 

127.1.1.0 * 255.255.255.0 U 0 0 0 tmm0

 

127.2.0.0 * 255.255.255.0 U 0 0 0 eth0

 

127.0.0.0 - 255.0.0.0 ! 0 - 0 -

 

[admin@BIGIP:Active] ~

 

 

When I attempt to source a connection from the BIGIP, it cannot find a route:

 

 

[admin@DEGLB01:Active] ~ ping 10.10.30.1

 

connect: Network is unreachable

 

[admin@DEGLB01:Active] ~

 

 

How is the BIGIP is returning my managment traffic? Obviously, if I manually add routes everything works as expected.

 

 

My only thought is that in the absence of a route, the BIGIP may be using the LINK::lasthop to return mgmt traffic to the sending MAC address.

 

 

Thanks

 

James