300-810 · Question #274
A company is setting up B2B instant messaging capability using a secure client integrated into the on-premises Cisco communication platform. During the setup, the engineer discovers that external mess
The correct answer is A. The SRV record for XMPP is not configured or is misconfigured.. External XMPP federation traffic is directed to the Expressway by DNS SRV records; if those records are absent or wrong, external partners cannot discover the endpoint and no traffic reaches the firewall.
Question
A company is setting up B2B instant messaging capability using a secure client integrated into the on-premises Cisco communication platform. During the setup, the engineer discovers that external messages from other businesses do not seem to reach the Cisco Expressway for instant messaging, but B2B calling seems to be working. Internal chat between clients and chat toward clients is working in home offices using Mobile and Remote Access. The engineer verified that the correct ports have been configured on the Cisco ASA, and the firewall rules on the expressway show no indication of any traffic. What is the cause of the issue?
Options
- AThe SRV record for XMPP is not configured or is misconfigured.
- BThe XMPP service is not running under services in Cisco IM and Presence Server.
- CThe XMPP service is not activated on the Cisco Expressway.
- DThe Cname record for XMPP is not configured or is misconfigured.
How the community answered
(59 responses)- A76% (45)
- B8% (5)
- C3% (2)
- D12% (7)
Why each option
External XMPP federation traffic is directed to the Expressway by DNS SRV records; if those records are absent or wrong, external partners cannot discover the endpoint and no traffic reaches the firewall.
XMPP federation between organizations is discovered via the DNS SRV record _xmpp-server._tcp, which external partners query to find the correct host and port for the Cisco Expressway-E. Because B2B calling uses different SRV records (_sip._tls) that are clearly working, the network path and firewall rules are correct - the missing or misconfigured XMPP SRV record means external domains never resolve a destination, so no traffic reaches the Expressway at all.
Internal chat and MRA chat are working, confirming the XMPP service on IM and Presence is running correctly.
Since MRA (which uses Expressway) is working for chat, the XMPP service is active on the Expressway.
A CNAME record is not used for XMPP federation discovery; the protocol relies specifically on SRV records, not CNAME records.
Concept tested: DNS SRV record requirement for XMPP B2B federation
Source: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/expressway/config_guide/X14-3/exwy_b_cisco-expressway-b2b-calls-config-guide/exwy_b_cisco-expressway-b2b-calls-config-guide_chapter_0110.html
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