Table Of Contents
SIP—Gateway Support for the bind Command
Information About SIP —Gateway Support for the bind Command
How to Configure SIP—Gateway Support for the bind Command
Verifying and Troubleshooting Tips
Configuration Examples for SIP —Gateway Support for the bind Command
SIP—Gateway Support for the bind Command
The Gateway Support for the bind Command feature introduces the bind command, which allows you to configure the source IP address of signaling packets or both signaling and media packets. Befor this feature was introduced the source address of a packet going out of a Cisco IOS gateway is not deterministic. The session protocols and VoIP layers depended on the IP layer to give the best local address and then used the address for the source address in signaling or media or both, even if multiple interfaces can support a route to the destination address.
Prerequisites
Cisco Unified Border Element
•Cisco IOS Release 12.2(8)T or a later release must be installed and running on your Cisco Unified Border Element.
Cisco Unified Border Element (Enterprise)
•Cisco IOS XE Release 2.5 or a later release must be installed and running on your Cisco ASR 1000 Series Router.
Information About SIP —Gateway Support for the bind Command
Prior to the Gateway Support for the bind Command feature the source address of a packet going out of the gateway was never deterministic. That is, the session protocols and VoIP layers always depended on the IP layer to give the best local address. The best local address was then used as the source address (the address showing where the SIP request came from) for signaling and media packets. Using this nondeterministic address occasionally caused confusion for firewall applications, because a firewall could not be configured with an exact address and would take action on several different source address packets.
The bind interface command allows you to configure a specific interface's IP address as the source IP address of signaling and media packets. The address that goes out on the packet is bound to the IP address of the interface specified with the bind command. Packets that are not destined to the bound address are discarded.
When you do not specify a bind address, or if the interface is down, the IP layer still provides the best local address.
With the bind command, SIP signaling and media paths can advertise the same source IP address on the gateway for certain applications, even if the paths use different addresses to reach the source. This eliminates confusion for firewall applications that, Without the binding, may have taken action on several different source address packets.
Table 1 lists the results of the bind command based on the state of the interface.
Note If there are active calls, the bind command will not take effect if it is issued for the first time or if it is issued while another bind command is in effect. A message is displayed reminding you that there are active calls and that the bind command change cannot take effect.
How to Configure SIP—Gateway Support for the bind Command
To configure the SIP—Gateway Support for the bind Command feature, complete these tasks:
•Setting the Bind Address (required)
•Setting a Source IP Address for Signaling and Media Packets (required)
•Verifying and Troubleshooting Tips
Setting the Bind Address
To set the bind address, complete the task in this section.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number voip
4. session target ipv4:destination-address
5. exit
DETAILED STEPSSetting a Source IP Address for Signaling and Media Packets
SIP configuration mode starts from voice-service VoIP configuration mode. When the router is in SIP configuration mode, several options are available, including the bind command. To enable this feature, review the prerequisites to make sure your network is compliant, and then complete the task in this section.
Prerequisites
•Endure you have Cisco IOS XE Release 2.5 or a later release installed and running on your Cisco ASR 1000 Series Router.
•Ensure that the gateway has voice functionality that is configurable for SIP.
•Establish a working IP network.
•Configure VoIP.
•Set the bind address prior to using the bind command.
SUMMARY STEPS
1. enable
2. configure terminal
3. voice service voip
4. sip
5. session transport {udp | tcp}
6. bind {control | all} source-interface interface-id
7. default {command}
8. exit
DETAILED STEPSVerifying and Troubleshooting Tips
Two show commands verify the correct settings for the bind command. The first enables you to verify a bound IP address. The second indicates the status of bind (enabled or disabled):
Verifying a Bound IP Address
The following examples show output for the show ip socket command, indicating that the bind address of the receiving gateway is set:
Router# show ip socketProto Remote Port Local Port In Out Stat TTY OutputIF
17 0.0.0.0 0 --any-- 2517 0 0 9 0
17 --listen-- 172.18.192.204 1698 0 0 1 0
17 0.0.0.0 0 172.18.192.204 67 0 0 489 0
17 0.0.0.0 0 172.18.192.204 5060 0 0 A1 0
Verifying Bind Status
The following example shows output for the show sip-ua status command, indicating that bind is enabled.
Router# show sip-ua statusSIP User Agent StatusSIP User Agent for UDP : ENABLEDSIP User Agent for TCP : ENABLEDSIP User Agent bind status(signaling): ENABLED 172.18.192.204SIP User Agent bind status(media): ENABLED 172.18.192.204SIP max-forwards : 6SIP DNS SRV version: 1 (rfc 2052)
To troubleshoot this feature, perform the following:
•Use the debug ccsip all command to enable all SIP debugging capabilities, or use one of the following SIP debug commands:
–debug ccsip calls
–debug ccsip error
–debug ccsip events
–debug ccsip messages
–debug ccsip states
•Use the show ip socket command to display IP socket information.
•Use the show sip-ua status command to verify if binding is enabled. See the show sip-ua status command for details.
Configuration Examples for SIP —Gateway Support for the bind Command
This section containd examples for SIP—Gateway Support for the bind Command feature:
•SIP—Gateway Support for the bind Command: Example
SIP—Gateway Support for the bind Command: Example
This section shows partial output from the show running-config command, indicating that bind is functional on receiving router 172.18.192.204.
ip subnet-zeroip ftp source-interface Ethernet0!voice service voipsipbind all source-interface FastEthernet0!interface FastEthernet0ip address 172.18.192.204 255.255.255.0duplex autospeed autofair-queue 64 256 1000ip rsvp bandwidth 75000 100!!