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Description

Few or all users may hit a blank page sporadically when accessing Service Now instance. 

The following information is required in order to troubleshoot any possible network issue:

1) Description of event (for example, the user cannot reach instance URL, or the user has intermittent latency to instance URL).

2) Source IP address (if at user end, this must be their public IP).

3) Destination IP address (if this is a ServiceNow IP, it will likely be the instance IP, but if the user is instead specifying an instance URL, have them determine what IP address they are accessing).

4) Ping and traceroute from user IP to <instance>.service-now.com

5) Ping and traceroute from application server to public user IP.

6) Application being used or destination port and protocol.

7) Is the customer going through VPN tunnel.

8) Any expected filtering (for example, ICMP) at the user endpoint.


Release or Environment

Any Release

Cause

When accessing Service Now instance through IAD data center, customer can hit a very rare F5 bug - ID773421, where some hosts in the pool were caching the MTU value incorrectly. The following error messages may be seen in the network capture(PCAP) file.

Error message: " Destination unreachable (Fragmentation needed and DF set) "

Resolution

1) To resolve the issue, our network team has to clear the cache at F5 or do an AHA transfer from IAD to SJC data center. 

AND

2) Our network team has to implement a change to create a custom profile to disable proxy-mss for the customer so that the issue doesn't happen again in future.


Article Information

Last Updated:2020-11-05 11:46:01
Published:2020-11-05