An IPinIP tunnel is implemented across two catalyst switches as follows:
1. Cat4500_VLAN400 <==> IPinIP <==> Cat3500_VLAN400
2. OSPFv2 across tunnel interface
The following behavior is observed:
3. Failure to complete FULL OSPF adjacency
3.1 Cat3500 side goes into INIT state
3.2 Cat4500 side goes into NULL state (-)
4. Input queue drops observed Tunnel_Interface_Cat4500
ACTION
5. Increased HOLD-QUEUE IN on Tunnel_Interface_Cat4500 to match value on corresponding Physical Interface (2000)
RESULT
6. OSPF Adjacency came back
ISSUE
When we 'stress' tested this link, SUPRISINGLY packet drops and OSPF adjacency loss returned when sending more than 40kbps...this is too low a threshold a Cat4500.
QUESTION
Does the cat4500 significantly de-prioritize Tunnel (IPinIP in this case) processing compared physical interfaces? i.e does the cat4500 process switch IPinIP traffic? Conversely, is there a way to improve IPinIP traffic processing on Cat4500?
Note: Cat4500 is running 12.1(13)EW
regards,
Ranga
