All Flashcards
What does MGCP use specifying and negotiating the media streams.
Session Description Protocol (SDP)
What port does MGCP leverage for control traffic?
UDP port 2427
What port does MGCP leverage for backhaul traffic?
TCP port 2428
What MGCP Call State command is sent from a call-control agent to an MGCP-controlled gateway for creating a new connection between two MGCP endpoints?
CreateConnection (CRCX)
What MGCP Call State command is sent from a call-control agent to an MGCP-controlled gateway that modifies the parameters associated with an existing connection?
ModifyConnection (MDCX)
What MGCP Call State command is bidirectional and used by a call-control agent to inform the gateway that it should terminate a connection and is also used by a Gateway to indicate that a connection needs to be terminated?
DeleteConnection (DLCX)
What MGCP Call State command is bidirectional and sends statistics associated with the connection when contacting the call-control agent?
DeleteConnection (DLCX)
What MGCP Call State command is sent from a call-control agent to an MGCP-controlled gateway that configures the gateway with bearer information, which specifies whether audio calls will be encoded using mu-law or A-law?
EndpointConfiguration (EPCF)
What MGCP Call State command is sent from a call-control agent to an MGCP-controlled gateway to instruct the gateway to inform the call-control agent when specific events such as on-hook/off-hook actions or DTMF tones occur on a specified endpoint?
NotificationRequest (RQNT)
What MGCP Call State command is sent from a call-control agent to an MGCP-controlled gateway to audit the status of an endpoint (port), such as bearer information, signal status, and event status?
AuditEnpoint (AUEP)
What MGCP Call State command is sent from a call-control agent to an MGCP-controlled gateway to discover the status of a connection, such as connection mode, call ID, and connection parameters?
AuditConnection (AUCX)
What MGCP Call State command is sent from an MGCP-controlled gateway to a call-control agent to inform the call-control agent when requested events occur such as on-hook/off-hook and digit reception?
Notify (NTFY)
What MGCP Call State command is sent from an MGCP-controlled gateway to a call-control agent to inform the call-control agent that the gateway is taking an endpoint or group of endpoints out of service or returning an endpoint or group of endpoints to service?
RestartInProgress (RSIP)
What are three types of MGCP Restarts?
- Restart (endpoint in service)
- Graceful (wait until call clearing)
- Forced (endpoint out of service)
What is the MGCP return code for Response Acknowledgement Messages as defined by RFC 3661?
000
What is the MGCP return code for Transactional Execution-related Messages as defined by RFC 3661?
1XX
What is the MGCP return code for Transactional Successful Messages as defined by RFC 3661?
2XX
What is the MGCP return code for Transient Error Messages as defined by RFC 3661?
4XX
What is the MGCP return code for Permanent Error Messages as defined by RFC 3661?
5XX
What are the various MGCP return codes as defined by RFC 3661 and what do they mean?
000: Response acknowledgement message 1XX: Transaction execution-related messages 2XX: Transaction successful messages 4XX: Transient error messages 5XX: Permanent error messages
What port does MGCP use to send messages?
UDP port 2427
What port does MGCP use to exchange keep-alive packets between an MGCP-controlled gateway and CUCM?
TCP port 2428
What MGCP command enables graceful switchback from one CUCM server to another in case of a CUCM server failure and what are the options?
ccm-manager switchback
graceful immediate never schedule-time uptime-delay
What are the 3 different categories of QoS and how strict is each?
IntServ - Strict
DiffServe - Less strict
Best Effort - Not strict
What is are 5 common QoS mechanisms?
- Classification and Marking
- Queuing
- Congestion Avoidance (RED or WRED)
- Policing and Shaping
- Link Efficiency
What is the difference between shaping and policing?
Policing is more strict. If traffic exceeds more than the specified bandwidth then it is often dropped. In the case of TCP traffic, it will be retransmitted.
Shaping is less strict. If traffic exceeds more than the specified bandwidth (CIR) then it is queued and sent as soon as bandwidth is available.
What are two common Link Efficiency mechanisms?
- RTP Header Compression (cRTP)
2. Link Fragmentation and Interleaving (LFI)
What is the size of a standard RTP Header?
40 Bytes
What are the two potential sizes of a compressed RTP Header and what do most systems default to?
2 Bytes (without UDP Checksum) 4 Bytes (with UDP Checksum)
What is the bandwidth amount where it makes sense to use LFI?
Less than 768 Kbps
If you have 768 Kbps or higher then do not use LFI.
What is the command to enable auto QoS for voice on a Cisco router running Frame-Relay?
Int serial 0/0/0.101
frame-relay interface-dlci 101
auto qos voip
What is the difference between using the “auto qos voip” command or the “auto qos voip trust” command on a Cisco router?
auto qos voip will use NBAR to identify well known traffic types.
auto qos voip trust will trust the already existing DSCP markings.
What port does the SIP protocol use?
TCP or UDP 5060
What port does the Secure SIP protocol use and what does it use for signaling?
Known as Secure SIP (SIPS). It uses TLS for signaling and operates on TCP port 5061.
What are two protocols that use SDP for negotiating media type and format?
MGCP and SIP
How is a resource in a SIP network identified?
By a Uniform Resource Identifier (URI).
What is the format of a typical SIP URI?
sip:username:password@host:port.
Name the 3 ways SIP can send DTMF, if they are sent in-band or out-of-band and if they are standards based or not.
- KeyPad Markup Language (KPML) - Out-Of-Band - Standards Based
- Unsolicited Notify (UN) - Out-Of-Band - Not Standards Based
- Network Termination Equipment (NTE) (RFC 2833) - In-Band - Standards Based
What are two ways a SIP phone can dial a destination and what types of phones do each?
SIP (Type-A) phone uses SIP dial rules SIP KPML (Type-B) phone uses KPML
How do SIP KPML phones process DTMF digits?
KPML is similar to SCCP in terms of the process used to collect each digit. The caller enters digits on the keypad of the phone, and digit analysis occurs in real time, after which CUCM routes the call to the destination device or translation/ route pattern.
How are SIP KPML DTMF digits carried to the call agent?
In SIP NOTIFY messages.
Where is KPML configured for KPML SIP phones in the CUCM and is KPML on by default?
Under the SIP Profiles and yes, it is on by default.
How are SIP dial rules delivered to a SIP type-A phone and what is that file called?
dialplan.xml is delivered to the phone via TFTP when the phone boots up.
How do SIP Type-A phones process digits?
When a caller enters digits on the phone keypad, the phone analyzes the dialed digits and compares them with the strings contained within the dialplan.xml file stored locally on the phone.
When there is a match to the dialed number and the timeout is set to 0, the phone sends to CUCM a SIP INVITE message that contains the entire called number.
What happens if the dialed number on a SIP Type-A phone does not match any of the strings contained within the diaplan.xml file?
The call will only be routed when the inter-digit timeout expires (or the caller presses “#” or “Dial”).
How does a SIP KPML Type-B phone process DTMF if the dialplan.xml file is downloaded to it?
KPML is disabled and the phone behaves in the same way as a Type-A SIP phone.
A hybrid of using KPML and dial rules is not supported, and SIP dial rules/ dial plan always take priority over KPML.
The exception to this statement is when CUCME is used and the last statement within the dial plan contains a dial pattern with a single wildcard character (.) as the last pattern in the dial plan.
What manages send and receive SIP messages and manages a session?
SIP User Agent (UA)
A SIP endpoint can act as both a user agent client (UAC) and a user agent server (UAS). True or False?
True
What initiates and sends requests and gets a response from a SIP UAS or SIP Proxy Server?
Hint: It is a logical role and only lasts for the duration of a SIP transaction.
SIP user agent client (UAC)
What responds to SIP requests by accepting, rejecting, or redirecting the request?
Hint: It is a logical role and only lasts for the duration of a SIP transaction.
SIP user agent server (UAS)
What SIP element provides routing, enforces policies, provides features, and authenticates and authorizes users?
SIP Proxy Server
What is a UAS server that provides address translation and that generates 3XX (Redirection) responses to requests it receives, thereby directing the client to contact an alternate set of URIs?
Hint: It also allows SIP proxy servers to redirect invites to external domains as well.
SIP Redirect Server
What is a SIP endpoint that accepts REGISTER requests from SIP UAs and places information received in those requests into a location service for the domain it handles?
Hint: This allows users to register their current locations.
SIP Registrar Server
What SIP element receives requests from UAs and then generates a new request on their path to the destination?
SIP back-to-back user agent (B2BUA)
What is a Cisco-developed protocol (now an open standard) that allows a single telepresence node in a multi-node system to multiplex the RTP and RTCP streams from all nodes in the system, dramatically reducing the number of call flows between two multi-node telpresence systems?
Telepresence Interoperability Protocol (TIP)
What are two feature sets within Intelligent Proximity?
- Intelligent Proximity for Mobile Voice
2. Intelligent Proximity for Content Sharing
What are two presentation display technologies?
Hint: One is SIP and one is H323.
- SIP - Binary Floor Control Protocol (BFCP)
2. H323 - H.239
What does presentation display during a video conference using a separate video channel in an H.323 environment?
H.239
What does presentation display during a video conference using a separate video channel in a SIP environment?
Binary Floor Control Protocol (BFCP)
There are two types of SIP messages. What are they?
- Request
2. Response
What type of SIP message is sent by a client to a server and is used to invoke certain methods (functions)?
Request message
What type of SIP message is sent by a server to a client in answer to the request and indicates the status of the request received?
Response message
What are the various SIP Methods for SIP requests?
Hint: There are 7.
INVITE REGISTER ACK BYE CANCEL OPTIONS PRACK (Provisional Response Acknowledgment)
What are the various SIP Request Methods?
Hint: There are 5.
Provisional (1XX) Success (2XX) Redirection (3XX) Server Error (5XX) Global Failure (6XX)
What SIP Method is used by a UA to initiate a session with a UAC?
Hint: When it arrives at a UAS, the UAS processes it and sends a suitable type of response message.
INVITE
What SIP Method is used by a UA to indicate its current IP address and the URLs for which it would like to receive calls to register its contact information.
Hint: Cisco SIP phones send their MAC addresses and register their lines with the primary CUCM using this method.
REGISTER
What SIP Method confirms reliable message exchange and is sent in reply to a final response message from a server?
ACK
What SIP Method terminates a session between two users?
BYE
What SIP Method terminates a pending request (a request for which a final response has not yet been received).
CANCEL
What SIP Method requests information about capabilities of a caller, without setting up a call?
OPTIONS
What SIP Method adds an acknowledgment system to the Provisional response (1XX) and is sent in response to a Provisional response?
PRACK
What SIP Response is informational in nature and indicates that a request has been received and is being processed? Give name and #.
Provisional (1XX)
What SIP Response indicates success (the action was successfully received, understood, and accepted)?
Success (2XX)
What SIP Response indicates that further action needs to be taken by the sender to complete the request, perhaps in case of a redirection in response to a UA by SIP Proxy?
Redirection (3XX)
What SIP Response indicates servers’ failure to fulfill a valid request by client?
Server Error (5XX)
What SIP Response indicates a global failure and that the request cannot be fulfilled at any server?
Global Failure (6XX)
What is a call-control and signaling protocol used to establish, control, and terminate calls between H. 323 endpoints.
H.225
What is a control channel protocol to transmit non-telephone signals such as information related to capabilities, jitter management, and flow control, establish logical channels for the transmission of media, and so on?
Hint: In certain cases, it can be tunneled within H. 225.
H.245
What is used for communication between H. 323 endpoints (such as Cisco Unified IP Phones, CUCM) and the gatekeeper and between the gatekeeper and a peer gatekeeper.
Hint: It has a number of messages for registration, admission, and status, most of which have a response of Confirmation or Reject.
H.225 RAS (Registration, Admission, and Status)
What provides security within the H. 323 suite, for both signaling and media?
H.235
What is a standard for multiple video channels within a single H. 323 session.
Hint: It enables dual streams for use in videoconferencing, one for live video and the other for presentation/ still images.
H.239
What series of protocols describes various supplementary services such as call transfer, call hold, and so on?
H.450
What series of protocols defines optional extensions that may be implemented by an endpoint or a gatekeeper Network Address Translation (NAT)/ firewall (FW) traversal?
H.460
What protocol and port do H.323 endpoints use for gatekeeper discovery?
H.225 RAS UDP port 1718
What port do H.323 endpoints use for gatekeeper H.225 RAS communication?
UDP port 1719
What are two ways that an H.323 gateway can initiate an H.323 session?
- fast start
2. slow start
What is a method of call setup that allows the media channels to be operational before the CONNECT message is sent?
H.323 Fast Start
