Using the DISPLAY EEDIAG output to tune your Enterprise Extender timers

The following sample display uses the same EE timer values as in Figure 1.

D NET,EEDIAG,SRQRETRY=3,LIST=DETAIL,CLEAR=SRQRETRY 
IST097I DISPLAY ACCEPTED
IST350I DISPLAY TYPE = EEDIAG   
IST2066I ENTERPRISE EXTENDER CONNECTION SRQRETRY INFORMATION  
.
.
IST2074I SUCCESSFUL SRQRETRY ATTEMPT =  0     OCCURRENCES =        98   
IST2074I SUCCESSFUL SRQRETRY ATTEMPT =  1     OCCURRENCES =         5   
IST2074I SUCCESSFUL SRQRETRY ATTEMPT =  2     OCCURRENCES =         2   
IST2074I SUCCESSFUL SRQRETRY ATTEMPT =  3     OCCURRENCES =         1   
.
.
IST314I END

The first IST2074I message displays attempt number 0 with 98 occurrences. To relate this to Figure 1, this means the LIVTIME interval (a) expired without receiving any inbound HPR data, and a TEST request (b) was sent. The partner EE node responded to this TEST within the SRQTIME interval (c). Receiving a response is considered a successful attempt. Because this TEST is not considered a retry, it is denoted by SUCCESSFUL SRQRETRY ATTEMPT = 0. This scenario increments the number of occurrences for attempt number 0 by one. This display indicates that 98 times, when the initial TEST was sent out to the EE partner, VTAM® received a reply from the partner within the first SRQTIME interval.

The second IST2074I message displays the attempt number of 1 with 5 occurrences. To relate this to Figure 1, this means that the LIVTIME interval (a) expired without receiving any inbound HPR data, and a TEST request (b) was sent. No response was received from the partner EE node within the first SRQTIME interval (c). VTAM then sends out the first SRQRETRY attempt (d) for the TEST request. The partner EE node responded to this TEST within the SRQTIME interval (e). Receiving a response is considered a successful attempt. Because this TEST is considered a retry, it is denoted by SUCCESSFUL SRQRETRY ATTEMPT = 1. This scenario increments the number of occurrences for attempt number by one. This display indicates that five times when the first SRQRETRY attempt for the TEST was sent out to the EE partner, VTAM received a reply from the partner within this SRQTIME interval.

The remaining IST2074I messages indicate the same information, but the attempt number and number of occurrences indicates on which SRQRETRY VTAM received a response. Generally, the number of nonzero occurrences in the high numbered SRQRETRY attempts should be minimal, if not zero. If there are any SRQRETRY attempts in the last or next-to-last retry, this indicates that there are conditions in your IP network that are causing long network delays. In these situations, VTAM is very close to an inoperative condition on these EE connections.

The defaults for the LDLC parameters are probably sufficient for most networks, but tuning the parameters might be appropriate depending on the design of the underlying IP network and the technologies being used there. For example, if RIP is being used as the dynamic routing update protocol, then longer convergence times are to be expected (as compared to OSPF), and therefore the LDLC parameters could be adjusted (for example, by bumping the number of SRQRETRY attempts, or increasing the SRQTIME interval value to lengthen the time EE LDLC waits before inoping the connections).