Configuring SIP Registration Proxy on Cisco UBE

In the end-to-end mode, Cisco UBE collects the registrar details from the Uniform Resource Identifier (URI) and passes the registration messages to the registrar. The registration information contains the expiry time for rate-limiting, the challenge information from the registrar, and the challenge response from the user.

Cisco UBE also passes the challenge to the user if the register request is challenged by the registrar. The registrar sends the 401 or 407 message to the user requesting for user credentials. This process is known as challenge.

Cisco UBE ignores the local registrar and authentication configuration in the end-to-end mode. It passes the authorization headers to the registrar without the header configuration.

Register Success Scenario

The figure below shows an end-to-end registration pass-through scenario where the registration request is successful.

Figure 1

End-to-End Registration Pass-through Mode--Register Success Scenario

The register success scenario for the end-to end registration pass-through mode is as follows:

1. The user sends the register request to Cisco UBE.
2. Cisco UBE matches the request with a dial peer and forwards the request to the registrar.
3. Cisco UBE receives a success response message (200 OK message) from the registrar and forwards the message to the endpoint (user).
4. The registrar details and expiry value are passed to the user.

Registrar Challenging the Register Request Scenario

The figure below shows an end-to end registration pass-through scenario where the registrar challenges the register request.

Figure 2

End-to-End Registration Pass-through Mode--Registrar Challenging the Register Request Scenario

The following scenario explains how the registrar challenges the register request:

1. The user sends the register request to Cisco UBE.
2. Cisco UBE matches the register request with a dial peer and forwards it to the registrar.
3. The registrar challenges the register request.
4. Cisco UBE passes the registrar response and the challenge request, only if the registrar challenges the request to the user.
5. The user sends the register request and the challenge response to the Cisco UBE.
6. Cisco UBE forwards the response to the registrar.
7. Cisco UBE receives success message (200 OK message) from the registrar and forwards it to the user.

In the peer-to-peer registration pass-through mode, the outgoing register request uses the registrar details from the local Cisco UBE configuration. Cisco UBE answers the challenges received from the registrar using the configurable authentication information. Cisco UBE can also challenge the incoming register requests and authenticate the requests before forwarding them to the network.

In this mode, Cisco UBE sends a register request to the registrar and also handles register request challenges. That is, if the registration request is challenged by the registrar (registrar sends 401 or 407 message), Cisco UBE forwards the challenge to the user and then passes the challenge response sent by the user to the registrar. In the peer-to-peer mode, Cisco UBE can use the authentication command to calculate the authorization header and then challenge the user depending on the configuration.

Note	The registrar command must be configured in peer-to-peer mode. Otherwise, the register request is rejected with the 503 response message.

Peer-to-Peer Mode--Call Flows

This section explains the following peer-to-peer pass-through mode call flows:

Register Success Scenario

The figure below shows a peer-to-peer registration pass-through scenario where the registration request is successful.

Figure 3

Peer-to-Peer Registration Pass-through Mode--Register Success Scenario

The register success scenario for a peer-to-peer registration pass-through mode is as follows:

1. The user sends the register request to Cisco UBE.
2. Cisco UBE matches the register request with a dial peer and forwards the register request to the registrar.
3. Cisco UBE receives a success message (200 OK message) from the registrar and forwards it to the endpoint (user). The following functions are performed:
   • Cisco UBE picks up the details about the registrar from the configuration.
   • Cisco UBE passes the registrar details and expiry value to the user.

Registrar Challenging the Register Request Scenario

The figure below shows a peer-to-peer registration pass-through scenario where the registration request is challenged by the registrar.

Figure 4

Peer-to-Peer Registration Pass-through Mode--Registrar Challenging the Register Request Scenario

The following scenario explains how the registrar challenges the register request:

1. The user sends the register request to Cisco UBE.
2. Cisco UBE matches the register request with a dial peer and forwards the register request to the registrar.
3. The user responds to the challenge request.
4. Cisco UBE validates the challenge response and forwards the register request to the registrar.
5. Cisco UBE receives a success message from the registrar and forwards it to the endpoint (user).

Note	You can configure Cisco UBE to challenge the register request and validate the challenge response.

This section explains SIP registration pass-through in the following registrar modes:

The figure below shows the call flow when the register overload protection functionality is configured on Cisco UBE:

Figure 5

Register Overload Protection

The following steps explain the register overload protection scenario:

1. The user sends a register request to Cisco UBE.
2. Cisco UBE matches the request with a dial peer and forwards the register request to the registrar.
3. The registration is rejected with a random retry value when the registration threshold value is reached.

Note	The call flow for the DNS query on the Out Leg is the same for the end-to-end and peer-to-peer mode.

The figure below shows the call flow when the rate-limiting functionality is successful:

Figure 6

Rate-limiting Success Scenario

The following steps explain a scenario where the rate-limiting functionality is successful:

1. The user sends the register request to Cisco UBE.
2. Cisco UBE matches the registration request with a dial peer and forwards it to the registrar. The outgoing register request contains the maximum expiry value if the rate-limiting functionality is configured.
3. The registrar accepts the registration.
4. Cisco UBE forwards the success response with the proposed expiry timer value.
5. The user sends the reregistration requests based on the negotiated value. Cisco UBE resends the register requests until the out-leg expiry timer value is sent.
6. Cisco UBE forwards the subsequent register request to the registrar, if the reregister request is received after the out-leg timer is reached.

1.    enable

2.    configure terminal

3.    voice service voip

4.    sip

5.    registrar server [expires [max value] [min value]]

6.    end

1.    enable

2.    configure terminal

3.    voice service voip

4.    sip

5.    registration passthrough [static] [rate-limit [expires value] [fail-count value]] [registrar-index [index]]

6.    end

1.    enable

2.    configure terminal

3.    dial-peer voice tag {pots | voatm | vofr | voip}

4.    voice-class sip registration passthrough static [rate-limit [expires value] [fail-count value] [registrar-index [index]] | registrar-index [index]]

5.    exit

1.    enable

2.    configure terminal

3.    sip-ua

4.    registration spike max-number

5.    end

Perform this task to configure Cisco UBE to route a call to the registrar endpoint.

Note	You must perform this configuration on a dial peer that is pointing towards the endpoint.

1.    enable

2.    configure terminal

3.    dial-peer voice tag {pots | voatm | vofr | voip}

4.    session target registrar

5.    exit

1.    enable

2.    configure terminal

3.    dial-peer voice tag {pots | voatm | vofr | voip}

4.    authentication username username password [0 | 7] password [realm realm [challenge]]

5.    exit

1.    enable

2.    show sip-ua registration passthrough status

3.    show sip-ua registration passthrough status detail

Router> enable

Router# show sip-ua registration passthrough status
 
CallId       Line         peer         mode In-Exp       reg-I Out-Exp       
============ ============ ============ ==== ============ ===== ============  
771          5500550055   1             p2p  64           1     64          
=============================================================================

Router# show sip-ua registration passthrough status detail
============================================================
Configured Reg Spike Value: 0
Number of Pending Registrations: 0
============================================================
Call-Id: 763
Registering Number: 5500550055
Dial-peer tag: 601
Pass-through Mode: p2p
Negotiated In-Expires: 64 Seconds
Next In-Register Due in: 59 Seconds
In-Register Contact: 9.45.36.5
----------------------------------------
 Registrar Index: 1
 Registrar URL: ipv4:9.45.36.4 
 Negotiated Out-Expires: 64 Seconds
 Next Out-Register After: 0 Seconds
============================================================