Cisco iOS拨号：拨打同行狩猎

创建以下两个VoIP拨号对等体以点5位数字，以数字11开头到两个不同的IP地址，代表Cisco Unified Communications Managers：拨号对象100 VoIP Destination-Pattern 11 ...优先级1会话目标IPv4：10.1.1.1拨号-peer voice 101 voip Destination-pattern 11… Preference 2 Session target ipv4: 10.1.1.2 Many of the other VoIP dial peer options have been omitted here because we’re going to focus on the preference command in this blog. The preference command is used to create a call routing hierarchy based on the default dial-peer hunting logic in Cisco IOS. The default dial-peer hunting in Cisco IOS has the following hierarchy: 1. Longest match (destination-pattern) 2. Preference 3. Random selection The dial-peer hunt <0-9> global command can be used to change the dial-peer hunting algorithm with the following options: 0—Longest match in phone number, explicit preference, random selection. 1—Longest match in phone number, explicit preference, least recent use. 2—Explicit preference, longest match in phone number, random selection. 3—Explicit preference, longest match in phone number, least recent use. 4—Least recent use, longest match in phone number, explicit preference. 5—Least recent use, explicit preference, longest match in phone number. 6—Random selection. 7—Least recent use. Dial-peers 100 and 101 have the same longest match against any 5-digit dialed pattern beginning with 11 (11001 as an example). The preference command is configurable as 0 through 10 with the default being a preference of 0. A preference of 0 is the highest priority while a preference of 10 is the lowest priority. Since preference 0 is the dial-peer default, preference 0 will not show up in the running configuration. I used a preference of 1 and 2 in dial peers 100 and 101 so the preference options can clearly be seen in the IOS configuration. Since a preference of 1 is considered to be higher priority than a preference of 2, dial-peer 100 will be used as long as 10.1.1.1 is available. If the CUCM server at 10.1.1.1 does not answer the phone call, the call will be routed to 10.1.1.2. Unfortunately, inbound calls from the PRI (PSTN) will never failover to the redundant CUCM server based on the default H.323 timers. When the provider forwards the Q.931 SETUP message to the customer, the provider starts a T310 timer. If the T310 timer expires before receiving a CALL PROCEEDING message back from the customer, the provider will timeout the call. The T310 timer is normally configured to a value of 10 seconds. The H.323 failover timer is also configured at 10 seconds in the Cisco router. To fix this issue, the following configuration is used: Voice class h323 1 H225 timeout tcp establish 3 ! Dial-peer 100 Voice-class h323 1 ! Dial-peer 101 Voice-class h323 1 Since the H.225 call control layer of H.323 uses TCP port 1720, if the TCP session cannot be established (SYN, SYN/ACK, ACK) to the primary call processing (CUCM) server within 3 seconds, the secondary call processing server will be attempted. In the next blog, we will continue our coverage of dial-peers. REFERENCES Cisco IOS Dial Peer Features http://www.cisco.com/en/US/docs/ios/12_3/vvf_c/dial_peer/dp_confg.html Global Knowledge Cisco Unified Communications classes www.globalknowledge.com/cisco Cisco Press Books – CVOICE / GWGK / TUC http://www.ciscopress.com/markets/detail.asp?st=44706 Cisco Call Manager T310 Tuning http://supportwiki.cisco.com/ViewWiki/index.php/Call_Failure_to_Long_Distance/Mobile_Destination