Cisco Cisco TelePresence Video Communication Server Expressway

Appendix 11 – Cluster name and DNS SRV records

Cisco VCS Deployment Guide: Cluster creation and maintenance (Cisco VCS X6)

Page 72 of 76

Note:



UDP is not a good transport medium for video – SIP messaging for video systems is too large to
be carried on a packet based (rather than stream based) transport. UDP is often used for audio
only devices.



_sip._tls,<fully.qualified.domain> is an SRV record also used by Microsoft OCS Edge servers.

Looking up .SRV records

Nslookup

nslookup -query=SRV _sip._tcp.example.com

Dig

dig _sip._tcp.example.com SRV

; <<>> DiG 9.4.1 <<>> _sip._tcp.example.com SRV

;; global options: printcmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44952

;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 4

;; QUESTION SECTION:

;_sip._tcp.example.com. IN SRV

;; ANSWER SECTION:

_sip._tcp.example.com. 1183 IN SRV 1 0 5060 sbc1.example.com.

_sip._tcp.example.com. 1183 IN SRV 1 0 5060 sbc2.example.com.

;; AUTHORITY SECTION:

example.com. 87450 IN NS ns1.mydyndns.org.

example.com. 87450 IN NS ns2.mydyndns.org.

;; ADDITIONAL SECTION:

sbc1.example.com. 1536 IN A 194.73.59.53

sbc2.example.com. 1376 IN A 194.73.59.54

ns1.mydyndns.org. 75 IN A 204.13.248.76

ns2.mydyndns.org. 10037 IN A 204.13.249.76

;; Query time: 0 msec

;; SERVER: 10.44.8.11#53(10.44.8.11)

;; WHEN: Mon Jul 26 11:09:59 2010

;; MSG SIZE rcvd: 243

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