[nsp] IPinIP Tunnel termination on Cat4500

[RANGARIRAYI MUVAVARIRWA]

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 Muvavarirwa

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