What does the GRE "adjacency fixup" message mean and imply?

j.dewiele · ‎05-08-2012

Hey,

I can't find documentation on this message:

*May 8 10:05:06: Tunnel114: adjacency fixup, 10.100.111.4->10.100.11.21, tos set to 0x60

Does anyone know why these messages show up and what they imply for routing through the GRE tunnel?

Thanks,

Joey

Peter Paluch · ‎05-11-2012

Hello Joey,

According to the document at

http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.4/troubleshooting/guide/tr34fwd.html

"Fixup is a direct pointer to a routine in the output path after a CEF rewrite. this is an optimized path if a CEF rewrite exists and can be used."

It seems that this adjacency fixup is related to an optimization of the CEF rewrite process (replacing a double rewrite with a single rewrite - just my guess here). In order to understand better the message you have received on your console, can you explain in more details what are the IP addresses 10.100.111.4 and 10.100.11.21? Are the in any way related to the tunnel source/destination? Do they appear as next-hop IP addresses for some route?

Best regards,

Peter

j.dewiele · ‎05-14-2012

This is sort of a "kiosk" deployment. We are using GRE tunnels to connect the Kiosks through to HQ. We have 9 tunnels per Kiosk.

The addresses are exactly the source and destination addresses of Tunnel114. This configuration is on the Kiosk router. I've shown two GRE tunnels going through the EZYVPN:

!On Kiosk Router:
!
interface Loopback114
ip address 10.100.11.21 255.255.255.252
!
interface Loopback115
ip address 10.100.11.25 255.255.255.252
!
...
!
interface Tunnel114
ip unnumbered Loopback114
tunnel source Loopback114
tunnel destination 10.100.111.4
!
interface Tunnel115
ip unnumbered Loopback115
tunnel source Loopback115
tunnel destination 10.100.111.5
!
...
!Routing into tunnel:
!
ip route 10.4.1.95 255.255.255.255 Tunnel114
ip route 10.4.1.96 255.255.255.224 Tunnel114
ip route 10.4.1.128 255.255.255.224 Tunnel114
ip route 10.4.1.160 255.255.255.224 Tunnel114
ip route 10.4.1.192 255.255.255.224 Tunnel114
ip route 10.4.1.224 255.255.255.224 Tunnel114
ip route 10.5.1.95 255.255.255.255 Tunnel115
ip route 10.5.1.96 255.255.255.224 Tunnel115
ip route 10.5.1.128 255.255.255.224 Tunnel115
ip route 10.5.1.160 255.255.255.224 Tunnel115
ip route 10.5.1.192 255.255.255.224 Tunnel115
ip route 10.5.1.224 255.255.255.224 Tunnel115
　
　
!On the HQ Router:
!
interface Loopback114
ip address 10.100.111.4 255.255.255.255
!
interface Loopback115
ip address 10.100.111.5 255.255.255.255
!
...
!
interface Tunnel114
ip unnumbered Loopback114
ip policy route-map Tunnel14_FromKiosk
tunnel source Loopback114
tunnel destination 10.100.11.21
!
interface Tunnel115
ip unnumbered Loopback115
ip policy route-map Tunnel15_FromKiosk
tunnel source Loopback115
tunnel destination 10.100.11.25
!
　

The policy maps traffic from a tunnel to a specific subinterface at HQ:

route-map Core11_FromKiosk permit 10

match interface Tunnel114

set interface FastEthernet0/0.1111

!

Thanks for your time.

Joey

j.dewiele · ‎05-14-2012

By the way, if I turn off CEF then the adjacency fixup messages go away. So your premise seems certianly correct.