IPSLA managed response paths created in Path Manager are not being set on the router

Document ID : KB000031359
Last Modified Date : 14/02/2018
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CONFIGURATION:

eHealth versions prior to 6.3.2.08

Cisco routers running IOS 15.3 and newer

ISSUE:

Response Paths created in the Path Manager are not being set up on Cisco routers running new 15.3 IOS code.

DETAILS:

The router responds to eHealth's set-request packet with an error:

The sniffer capture shows following in response:

 

Error-status = bad value

Error-index = 12

 

The OID with index 12 is creating the problem, which is:

1.3.6.1.4.1.9.9.42.1.2.2.1.4 rttMonEchoAdminPktDataResponseSize

 

Description:

"This object represents the number of octets to be placed into the ARR Data portion of the response message. This value is passed to the RTT Echo Server via a field in the ARR Header.

For non-ARR RTT request/response (i.e. ipIcmpecho) this value will be set by the agent to match the size of rttMonEchoAdminPktDataRequestSize, when native payloads are supported.

REMEMBER: The ARR Header overhead is not included in this value. This object is only supported by SNA protocols."

 

CAUSE:

Cisco has advised that we need to remove any set command for the 12th variable or 1.3.6.1.4.1.9.9.42.1.2.2.1.4.  Which is the 'response size' variable. There was a change in Cisco's IOS starting in the 15.3 code level. When it comes to setting response payload size, they did quite a few changes:

Internal enhancement request CSCuc23025 - Udp Jitter Variable Length Response Size. This enhancement that allows the response size to be set for UDP Jitter. The code does not consider the response size setting at all for any non UDP Jitter operations. customers will need to remove this OID when configuring ICMP Echo.

The Default Response size is 0, which basically means it is ignored, even for a UDP Jitter probe. The old code would have accepted the snmpset to the object, but never did anything with it in regard to setting data response sizes. Basically, setting response size for ICMP Echo probes is wrong. In the old IOS code it was accepted, but most of the time it didn't do anything. In the new IOS code it will be rejected.

 

SOLUTION:

Starting with eHealth 6.3.2.08, a new Discover Policy paramater has been added which will need to be set to a value of "Yes" when attempting to discover response paths such as the above on Cisco routers running IOS 15.3 and later:

 

Name: Discover - Discover Response element for new Cisco IOS 15.3.3 

Symbol: NH_DISCOVER_CISCO_RESP_153 

Description: Discover Response element (without rttMonEchoAdminPktDataResponseSize) for new Cisco IOS 15.3.3.