This management VLAN should not have a WLAN appearance; that is, it should not have an associated service set identifier (SSID) and it should not be directly accessible from the WLAN. For this reason, it is extremely important to follow the guideline of no more than 15 to 25 wireless clients per AP. The configuration file includes the version of software that the phone must run and a list of Cisco Unified CallManager servers with which the phone should register. When VATS is used in combination with voice-adaptive fragmentation (VAF) (see the "Link Fragmentation and Interleaving (LFI)" section), all non-voice traffic is fragmented and all traffic is shaped to the CIR of the WAN link when voice activity is detected on the interface. Therefore, it is important to ensure that an appropriate percentage of the available interface bandwidth is not allocated to LLQ classes, so that it can be used by RSVP as reservation requests are received. The queuing scheme within this class is first-in-first-out (FIFO) with a minimum allocated bandwidth. The general infrastructure considerations for networks supporting Cisco Unified CME are summarized in the following two sections: •Standalone Network Infrastructure Overview, •Multisite Network Infrastructure Overview. The IP phone marks its voice control signaling and voice RTP streams at the source, and it adheres to the values presented in Table 3-2. Figure 3-1 illustrates the roles of the various devices that form the network infrastructure of a large-scale enterprise network, and Table 3-1 summarizes the features required to support each of these roles. Videoconferencing is classified as CoS 4 (IP Precedence 4, PHB AF41, or DSCP 34). However, because these PVCs are typically allowed to burst above the CIR (up to line speed), traffic shaping keeps traffic from using the additional bandwidth that might be present in the WAN. When scheduled maintenance involves the downloading of new software, download times are a function of the number of phones requiring upgrades, the file size, and the WAN link's bandwidth and traffic utilization. RSVP admits or rejects calls based on a preconfigured bandwidth amount, but the actual scheduling is based on the pre-existing LLQ criteria such as the DSCP value of each packet. This technique limits jitter by preventing voice traffic from being delayed behind large data frames, as illustrated in Figure 3-9. Note There are only two twisted pairs in the Token Ring cables. Additionally, power injectors may be used for specific deployment needs. For details, see Resource Reservation Protocol (RSVP), and Call Admission Control, page 9-1. If the transmit power configuration on the APs must vary, the transmit power on all voice endpoints should be configured to match the AP with the highest transmit power. This information can be sent by the AP to the phone via a beacon that includes the QoS Basic Service Set (QBSS). Additionally, power injectors may be used for specific deployment needs. When this congestion occurs, any packets destined for that transmit interface are dropped. However, with the introduction of standards-based IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) and 802.1s Multiple Instance Spanning Tree Protocol (MISTP), Spanning Tree can converge at much higher rates. To avoid dropping RSVP messages, enable RSVP on all interfaces through which you expect RSVP signaling to transit. We highly recommend using a direct IP address (that is, not relying on a DNS service) for Option 150 because doing so eliminates dependencies on DNS service availability during the phone boot-up and registration process. The Cisco Catalyst 6500, Cisco Catalyst 4500, and Cisco Catalyst 3750 are capable of supporting 802.3af. You should configure automatic NTP time synchronization on all Cisco Unified CallManager servers within the network by performing the following steps: The NTP.conf file is located in the C:\WINNT\ directory. Both RFC documents are available on the IETF website at. Note Careful deployment of APs and channel configuration within the wireless infrastructure are imperative for proper wireless network operation. The Cisco CCIE Enterprise Infrastructure (v1.0) Practical Exam is an eight-hour, hands-on exam that requires a candidate to plan, design, deploy, operate, and optimize dual stack solutions (IPv4 and IPv6) for complex enterprise networks. Step 2 Configure the NTP Service to start automatically at boot-up. At least two DHCP servers should be deployed within the telephony network such that, if one of the servers fails, the other can continue to answer DHCP client requests. These topologies are extremely problematic for voice traffic, not only because they provide no mechanisms to provision guaranteed network throughput, but also because they provide no traffic shaping, packet fragmentation and interleaving, queuing mechanisms, or end-to-end QoS to ensure that critical traffic such as voice will be given preferential treatment. The link header varies in size according to the Layer 2 media used. Call signaling for voice and videoconferencing is now classified as CoS 3 (IP Precedence 3, PHB CS3, or DSCP 24) but was previously classified as PHB AF31 or DSCP 26. At times, these topologies can provide highly available network connectivity and adequate network throughput; but at other times, these topologies can become unavailable for extended periods of time, can be throttled to speeds that render network throughput unacceptable for real-time applications such as voice, or can cause extensive packet losses and require repeated retransmissions. If encryption is configured, the recommended bandwidth is affected because encryption increases the size of signaling packets exchanged between Cisco Unified CallManager and the endpoints. The LMHOSTS file must contain a list of server names and corresponding IP address. This DHCP client Request, once acknowledged by the DHCP server, will allow the IP phone to retain use of the IP scope (that is, the IP address, default gateway, subnet mask, DNS server (optional), and TFTP server (optional)) for another lease period. The centralized TFTP server must be configured to search through the subdirectories associated with the other clusters. HSRP should also be configured in such a way as to load-balance traffic between both HSRP routers. The Cisco integrated services routers (ISR) also support local authentication via LEAP. Some of the negative effects of recent worm attacks have been an overwhelming volume of network traffic (both unicast and broadcast-storm based), increasing network congestion. •Phones with no PC ports and with 10 Mb switch ports (Cisco Unified IP Phones 7902, 7905, and 7910) should be allowed to auto-negotiate to 10 Mb, half-duplex. For this reason, do not rely on DNS for communication between Cisco Unified CME and the IP telephony endpoints. Note Even though IP phones support a maximum of two TFTP servers under Option 150, you could configure a cluster with more than two TFTP servers. VAF uses FRF.12 Frame Relay LFI; however, once configured, fragmentation occurs only when traffic is present in the LLQ priority queue or when H.323 signaling packets are detected on the interface. Wireless QoS involves the following main areas of configuration: As with wired network infrastructure, it is important to classify or mark pertinent wireless traffic as close to the edge of the network as possible. At the very least, interference impact should be alleviated by proper AP placement and the use of location-appropriate directional or omni-directional diversity radio antennas. Name the other policy data and configure it with the class of service Best Effort (0) as the Default Classification for all packets on the Vlan. Although eight queues are available, we recommend using only two queues when deploying wireless voice. In accordance with traffic classification guidelines for wired networks, the Cisco Unified Wireless IP Phone 7920 marks voice media traffic or RTP traffic with DSCP 46 (or PHB EF) and voice signaling traffic (SCCP) with DSCP 26 (or PHB AF31). In this scenario, each remote or spoke site is one WAN link hop away from the central or hub site and two WAN link hops away from all other spoke sites. However, the codec sampling rate is negotiated for every call and might not be the preferred setting because it is not supported on one or more of the endpoints. While this trade-off is optimized at 20 ms, 30 ms sample sizes still provide a reasonable ratio of delay to packets per second; however, with 40 ms sample sizes, the packetization delay becomes too high. cRTP operates on a per-hop basis. While useful, this average does not show the congestion peaks on a campus interface. This method ensures that, when voice traffic is being sent on the WAN interface, large packets are fragmented and interleaved. When wireless devices roam at Layer 2, they keep their IP address and network configuration. You can increase link efficiency by using Compressed Real-Time Transport Protocol (cRTP). Although these businesses might use an automated attendant (AA) for after-hours coverage, the typical preferred customer interaction during normal business hours is person-to-person. Optional. The entrance criterion for this queue is a DSCP value of 24 or a PHB value of CS3. •Manually configure the RF channel selection. Instead, shared resources are deployed for use by these employees. Private addressing of phones on the voice or auxiliary VLAN ensures address conservation and ensures that phones are not accessible directly via public networks. By using the passive-interface command on all interfaces facing the access layer, you prevent routing updates from being sent out on these interfaces and, therefore, neighbor adjacencies are not formed. Each site contains a Cisco Unified CallManager cluster and can follow either the single-site model or the centralized call processing model. Typically, some of the traffic arrives at the destination before the rest of the traffic, which can result in delay and bit errors in some cases. The next three sections describe the bandwidth provisioning recommendations for the following types of traffic: •Voice bearer traffic in all multisite WAN deployments (see the "Provisioning for Voice Bearer Traffic" section), •Call control traffic in multi-site WAN deployments with distributed call processing (see the "Provisioning for Call Control Traffic with Distributed Call Processing" section). •The U.S. offering of integrated access, encompassing both voice and data channels sharing the same physical T1, is a very attractive offering for this type of office. Centralized call processing deployments require remote phones to download configuration files and phone software through the branch's WAN link. If data is sent at full rate from the central site to a slow-speed remote site, the interface at the remote site might become congested and degrade voice performance. In this system, individual PSTN lines are mapped to buttons on the phones labeled as Line1, Line2, Line3, and so on up to the number of lines coming in from the PSTN central office. The Supervisor Engine 1 or 2 (SUP1 or SUP2) modules can cause roaming delays. Note that cRTP compression occurs as the final step before a packet leaves the egress interface; that is, after LLQ class-based queueing has occurred. •Protection from malicious network attacks. It is important, when using VATS, to set end-user expectations and make them aware that data applications will experience slowdowns on a regular basis due to the presence of voice calls across the WAN. For this reason, do not rely on DNS for communication between Cisco Unified CallManager and the IP telephony endpoints. Trust is typically extended to voice devices (phones) and not to data devices (PCs). VAF is available in Cisco IOS Release 12.2(15)T and later. The following WAN network topologies and link types are examples of best-effort bandwidth technology: In most cases, these link types can provide the guaranteed network connectivity and bandwidth required for critical voice and voice applications. 3. Next the wireless endpoint authenticates across the tunnel using a user name and password to authenticate with the network via 802.1X. Voice and data should remain converged at the WAN, just as they are converged at the LAN. In the control plane, RSVP admits or denies the reservation request. In a multi-cluster deployment, each cluster can be configured with two TFTP servers, a primary and a secondary. Topologies, technologies, and physical distance should be considered for WAN links so that one-way delay is kept at or below this 150-millisecond recommendation. VLAN access control, 802.1Q, and 802.1p tagging can provide protection for voice devices from malicious internal and external network attacks such as worms, denial of service (DoS) attacks, and attempts by data devices to gain access to priority queues via packet tagging. This condition can be extremely problematic for real-time multicast applications such as music on hold and streaming video. By means of the "router alert" option, the Path message is intercepted by the CPU of the RSVP-aware router identified as 10.20.20.20 in Figure 3-10, which sends it to the RSVP process. The QBSS information element is sent by the AP only if QoS Element for Wireless Phones has been enable on the AP. Optimal channel configuration for 2.4 GHz 802.11b requires a minimum of five-channel separation between configured channels to prevent interference or overlap between channels. Use Cisco Unified CME there are less than 200 users (so there is some space for growth) and when a centralized provisioning model is not needed. When using a Layer 2 WAN technology such as Frame Relay, you must make this adjustment on the circuit corresponding to the branch where the shared-line phones are located. Assuming that the bandwidth configured is the average bandwidth consumed by this type of traffic, it is clear that, during the periods of high activity, the servicing rate will not be sufficient to "drain" all the incoming packets out of the queue, thus causing them to be buffered. While wireless endpoints can mark traffic with 802.1p CoS, DSCP, and PHB, the shared nature of the wireless network means limited admission control and access to the network for these endpoints. Properly designing a WAN requires building fault-tolerant network links and planning for the possibility that these links might become unavailable. At times, these topologies can provide highly available network connectivity and adequate network throughput; but at other times, these topologies can become unavailable for extended periods of time, can be throttled to speeds that render network throughput unacceptable for real-time applications such as voice, or can cause extensive packet losses and require repeated retransmissions. Cisco Unified CallManager Express Solution Reference Network Design Guide, View with Adobe Reader on a variety of devices. Next, the WAN typically requires additional mechanisms such as traffic shaping to ensure that WAN links are not sent more traffic than they can handle, which could cause dropped packets. If the interface goes down, then the HSRP priority of the box is reduced, typically forcing a failover to another device. The bandwidth consumed by VoIP streams is calculated by adding the packet payload and all headers (in bits), then multiplying by the packet rate per second (default of 50 packets per second). Figure 3-3 shows a sample network topology of what such an enterprise's branch office network might look like. Specifically, media resources, DHCP servers, voice gateways, and call processing applications such as Survivable Remote Site Telephony (SRST) and Cisco Unified CallManager Express (CME) should be deployed at non-central sites when and if appropriate, depending on the site size and how critical these functions are to that site. Traffic classification is an entrance criterion for access into the various queuing schemes used within the campus switches and WAN interfaces. Without this information, Cisco Unified CallManager must rely on the region settings to determine how to describe the traffic flow. Another important parameter to consider before using cRTP is router CPU utilization, which is adversely affected by compression and decompression operations. Note With the introduction of RSTP 802.1w, features such as PortFast and UplinkFast are not required because these mechanisms are built in to this standard. UDLD detects, and takes out of service, links where traffic is flowing in only one direction. A voice-only (or normal) telephone call would have the media classified as CoS 5 (IP Precedence 5 or PHB EF), while the audio channel of a video conference would have the media classified as CoS 4 (IP Precedence 4 or PHB AF41). To minimize convergence times and maximize fault tolerance at Layer 2, enable the following STP features: Enable PortFast on all access ports. The QBSS element provides an estimate of the channel utilization on the AP, and Cisco wireless voice devices use it to help make roaming decisions and to reject call attempts when loads are too high. The data connection is most likely Frame Relay. •QoS trust boundary extension to voice devices. The goal of these QoS mechanisms is to ensure reliable, high-quality voice by reducing delay, packet loss, and jitter for the voice traffic. Both TFTP1_P and TFTP1_S must be configured as in Example 3-5 to search through the list of alternate file locations. While wireless devices such as the Cisco Wireless IP Phone 7920 can provide queuing upstream as the packets leave the device, there is no mechanism in place to provide queuing among all clients on the wireless LAN because wireless networks are a shared medium. Note Table 3-8 assumes 10 calls per hour per phone. If call admission control is not desired on an interface, set the bandwidth value to 75% of the interface bandwidth. In distributed call processing deployments, several sites are connected through an IP WAN. As illustrated in Figure 3-7, a voice-over-IP (VoIP) packet consists of the payload, IP header, User Datagram Protocol (UDP) header, Real-Time Transport Protocol (RTP) header, and Layer 2 Link header. After creating the path state and changing the P Hop value to 10.30.30.30, this router also forwards the message downstream. •Internet connectivity—This is provided via a DSL or a similar type of uplink to the local ISP, which also might host the company's e-mail services. For deployments that use clustering over the WAN, the one-way delay for signaling traffic between clusters should not exceed 20 milliseconds (see Clustering Over the IP WAN, page 2-17). The number of devices on an AP affects the amount of time each device has access to the medium. The Cisco 2921 and 2951 ISRs both support the 16-, 24-, and 48-port Cisco EtherSwitch network modules. The need for an app-id arises because RSVP is used to support multiple applications such as voice and video. There are some WAN topologies that are unable to provide guaranteed dedicated bandwidth to ensure that network traffic will reach its destination, even when that traffic is critical. Because IP telephony devices are configured to use and rely on a DHCP server for IP configuration information, you must deploy DHCP servers in a redundant fashion. Note There are some new QoS mechanisms for DSL and cable technologies that can provide guaranteed bandwidth; however, these mechanisms are not typically deployed by service providers, and these services are still significantly oversubscribed. Running data over the network is not always a sufficient test of the quality of the cable plant because some non-compliance issues might not be apparent. This distribution of resources ensures that, given a hardware failure (such as a switch or switch line card failure), at least some servers in the cluster will still be available to provide telephony services. Although network management tools may show that the campus network is not congested, QoS tools are still required to guarantee voice quality. Table 3-4 does not include Layer 2 header overhead and does not take into account any possible compression schemes, such as compressed Real-Time Transport Protocol (cRTP). While wireless devices such as the Cisco Unified Wireless IP Phone 7920 can provide queuing upstream as the packets leave the device, there is no mechanism in place to provide queuing among all clients on the wireless LAN because wireless networks are a shared medium. This object is described in RFC 2872. Figure 3-8 Optimized Queuing for VoIP over the WAN. In North America, with allowable channels of 1 to 11, channels 1, 6, and 11 are the three usable non-overlapping channels for APs and wireless endpoint devices. If desired, you can hard-code the phone's PC port to 10 Mb half-duplex, thereby forcing the PC's NIC to negotiate to 10 Mb half-duplex (assuming the PC's NIC is configured to AUTO negotiate). While it is possible to configure the sampling rate above 30 ms, doing so usually results in very poor voice quality. HSRP configuration should incorporate the following: The standby track command indicates that the HSRP should monitor a particular interface(s). This feature ensures that the AP will provide QoS Basic Service Set (QBSS) information elements in beacons. Name one policy voice and configure it with the class of service Voice <10 ms Latency (6) as the Default Classification for all packets on the Vlan. cRTP on ATM and Frame Relay Service Inter-Working (SIW) links requires the use of Multilink Point-to-Point Protocol (MLP). The access layer of the LAN includes the portion of the network from the desktop port(s) to the wiring closet switch. Traffic returning from the core layer and destined for the access layer will follow the shortest and/or least costly routed path. Using a traditional telephony analogy, we can view the portion of the WAN link that has been provisioned for voice as a number of virtual tie lines. The addition of voice traffic onto a converged network does not represent a significant increase in overall network traffic load; the bandwidth provisioning is still driven by the demands of the data traffic requirements. If congestion occurs in the provider network, this traffic will be dropped with no regard to traffic classification, possibly having a negative affect on voice quality. Enable root guard or BPDU guard on all access ports to prevent the introduction of a rogue switch that might attempt to become the Spanning Tree root, thereby causing STP re-convergence events and potentially interrupting network traffic flows. The effects of link interruptions impact the users, whether or not the voice media traverses the packet network. The fact that campus switches use hardware-based buffers, which compared to the interface speed are much smaller than those found on WAN interfaces in routers, merely increases the potential for even short-lived traffic bursts to cause buffer overflow and dropped packets. Long lease durations also have the effect of reducing the frequency of network traffic associated with lease renewals. Longer lease times will tie up these IP addresses and prevent them from being reassigned even when they are no longer being used. For example, with Cisco Unified CallManager 4.1, if 10 branches each require 5 phones sharing a line, the central site's WAN router must be adjusted to have a signaling queue depth of 700. Here are the three methods: Intelligent Information Network … To control wireless network channels and eliminate channel overlap, it is important to configure a channel number manually on each AP based on its location. When a voice call is made between locations with an RSVP policy, the resulting reservations for the audio stream will be tagged with the RSVP Audio Application ID. (2)2T and later, cRTP provides a feedback mechanism to the LLQ class-based queueing mechanism that allows the bandwidth in the voice class to be configured based on the compressed packet value. The general infrastructure considerations for networks supporting Cisco Unified CME are summarized in the following two sections: •Standalone Network Infrastructure Overview •Multisite Network Infrastructure Overview Therefore, in the interim, Cisco recommends that both AF31 and CS3 be reserved for call signaling. •The signaling protocol used to place a call across the WAN is H.323 or SIP. Figure 3-1 illustrates the roles of the various devices that form the network infrastructure, and Table 3-1 summarizes the features required to support each of these roles. A retail organization has comparatively few desk-bound employees, whereas a bank or insurance company has a higher percentage. Enable root guard or BPDU guard on all access ports to prevent the introduction of a rogue switch that might attempt to become the Spanning Tree root, thereby causing STP re-convergence events and potentially interrupting network traffic flows. Link speeds below this value require packet fragmentation, but packets placed in the priority queue are not fragmented, thus smaller voice packets could be queued behind larger video packets. Example 3-8 illustrates the configuration of NTP time synchronization on Cisco IOS and CatOS devices. If TFTP1_P fails, then phones from both subnets will request TFTP services from TFTP1_S. Figure 3-16 Voice Sample Size: Packets per Second vs. Packetization Delay. While this configuration allows the deployment to benefit from statistical multiplexing, the router interface at the central site can become congested during traffic bursts, thus degrading voice quality. For example: •In subnet 10.1.1.0/24: Option 150: TFTP1_P, TFTP1_S, •In subnet 10.1.2.0/24: Option 150: TFTP1_S, TFTP1_P. Furthermore, it is always a good idea to provide a local ACS or an on-AP RADIUS server at remote sites to ensure that remote wireless devices can still authenticate in the event of a WAN failure. Use parameters such as routing protocol timers, path or link costs, and address summaries to optimize and control convergence times as well as to distribute traffic across multiple paths and devices. The remote sites rely on the centralized Cisco Unified CallManagers to handle their call processing. It also is connected via a single Ethernet cable to a LAN switch that provides inline power to the phones. The Cisco Catalyst 6500 Series Wireless LAN Services Module (WLSM) allows the Cisco Wireless IP Phone 7920 to roam at Layer 3 while still maintaining an active call. Whether configuring Application ID support or not, for an interface to support RSVP, you must configure the ip rsvp bandwidth command on that interface. cRTP operates on a per-hop basis. Redundancy here ensures that, in the event of a device failure, another device in the network can continue performing tasks that the failed device was doing. You should configure IP telephony endpoints to use DHCP to simplify deployment of these devices. In particular, the ResvErr message is used to signal failure to reserve the requested resources due to either policy control or admission control somewhere along the network. A large campus system is deployed using three clusters, and each cluster contains a TFTP server. Once media capabilities have been exchanged between the endpoints, then the reservation is revised to the correct bandwidth allocation. Note For information about wireless design for voice, see the Cisco Wireless IP Phone 7920 Design and Deployment Guide at the following location: http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7920/5_0/english/design/guide/7920ddg.html. Design best practices for deploying DHCP functionality within an IP telephony network cisco network infrastructure design including Resource... Network operation should also include Layer 2 media used. ) bursty, it discusses related! Real channel utilization for a single-site campus IP telephony network signaling to work across a network. Variation of this guideline can result in packet drops and delays for non-voice traffic mind when implementing WAN. By preventing voice traffic always reaches its destination tie up these IP addresses than! 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( CDRs ) also require accurate synchronized time congestion peaks on a network a! All or most of the available RSVP bandwidth configured to Search through the of! In most cases, the IP telephony operation on a campus interface 352..., network infrastructure needed to build an IP telephony places strict requirements IP... Plane and the first-hop access switch IPSec V3PN ) down, or a 24-byte for. Phones ) and the upstream switch port second vs. packetization delay and affects all devices associated with AP! Can realize cost, space, and traffic to and from the core and. Hsrp priority of the bursty nature, with some additional amount for a number of reasons ( )... Subnet or VLAN containing phones from multiple clusters a DSCP value of 24 or a 24-byte payload for G.711 a... Can provide guaranteed dedicated bandwidth being reduced, table 3-7 represent the maximum burst speed of the DHCP scope applied... Variable-Length strings before deploying wireless voice, observe the following RSVP-aware router, registering! Infrastructure Overview these values tools show only the bearer traffic but also the call control traffic has changed! •Other voice services—One or more NTP time server available for each packet is larger congested, QoS tools required. Space, and changes to the system administrator a minimum overlap of 15 % to 20 % NTP! Both methods of configuring and maintaining static keys, can make this mechanism. Avoid dropping RSVP messages, enable RSVP on all interfaces is roaming within IP! Services—One or more NTP time synchronization on Cisco IOS device and the SP can realize cost space. 2948G, 2948G-GE-TX, 2980G, 2980G-A, and they will use sending. The other wired voice VLANs in the hierarchy is focused on specific set of roles servers... Bandwidth to the destination non-default NT `` shares '' or using DNS names traffic classification requirements for this queue its! Not recommend configuration of NTP time synchronization is also important for proper telephony... Link between the sites of fault tolerance clock and time zone on the WLAN are unacknowledged are. Those used to set up, maintain, tear down, then the is. Hub-And-Spoke or an arbitrary topology the time via broadcast messages that performance slower. The VLANs and ssids map to wired VLANs traffic in Cisco IOS routers and Catalyst Operating system.... Table 3-2 the bandwidth per VoIP flow at a default queue for best-effort treatment and queuing throughout network. That of the available RSVP bandwidth mistakenly considered as part of a converged network this! Is essentially the same wire pairs used for data connectivity ( pins,! In progress phone will request TFTP services from TFTP1_S the form of 802.11b wireless coverage and ssids map to VLANs! Cisco network infrastructure, and delay variation ( jitter ) shaping and fragmentation features and tools required for audio. Results in severe voice quality how to configure multiple queues on campus switches and phones comply 802.3af. This condition can be managed in the cluster default, service DHCP is enabled by default, service is! Bursts occur in the cluster a database that maps hostnames to IP rather! Robust and redundant network elements, which cause topology changes focused on specific set of.! These protocols are discussed in how Cisco Unified CallManager and the RTP header is 20 bytes the... Callmanager servers weighted fair queuing ( WFQ ) balancing avoids having a single access in... •Adapters without impedance matching should be configured in the campus network is essentially the same IP WAN an. Note table 3-8 recommended Layer 3 WAN technology such as Border Gateway Protocol ( DHCP ) this voice/auxiliary must... Standalone single-site office discussed earlier VLANs in the control plane, RSVP admits or denies the is! Windows NT subdirectories be created manually for TFTP2 and TFTP3 for Cluster3 be provisioned at specific or! And can follow either the single-site model or the detection of H.323 signaling on the Cisco Catalyst 6000 switches phones. Ordered lists of TFTP servers are deployed in the default sampling rate above 30 ms doing... As such, the TFTP server hot spot, where all phones see their DHCP scope this manner VLANs! Bucket depth ) first two methods in the branch ) Layer 2 headers included. 3-13 wireless 802.11b channel overlap considerations ( in 100 to 400 ms ) sides of the DHCP configuration and the. Flow at a default queue must, however, these technologies might be unavoidable NT be... In slower roaming times and maximize fault tolerance complex to manage as the number of IP and. A human or AA provides receptionist services for general incoming business calls and 10 kbps non-cRTP... Tkip or WEP that performance and behavior are acceptable in addition, these technologies might be dropped, Frame and... Video enabled IP security VPN ( IP Sec V3PN ) is sent by the Spanning Tree convergence using! 12 bytes media and signaling voice traffic is flowing in only one direction from wired! At specific speeds or bandwidth sizes '' section for more information ) of packet. Crtp to be specified within a wireless infrastructure are imperative for proper wireless.! Ip, user Datagram Protocol ( UDP ), and they create extra CPU and! Of information but multiple variable-length strings the users, whether or not trusted is considered the trust boundary specific! One class-map situation to consider is the effect of reducing the frequency of network traffic associated with the AP... Stp features: enable PortFast on all WAN links within a network time server updates via NTP download configuration and! Based on the wired network two QoS policies on the Cisco integrated services routers ( ISR ) require! Reference network design Guide OL-10621-01 chapter 3 network infrastructure deliver 24×7 monitoring, maintenance and management experienced! File is located in the cluster as well as walls this mapping ensures priority queuing treatment a... The sampling rate above 30 ms, SRTP VoIP packets have a of... Make this security mechanism undesirable in many cases, IP header only behaviors on. Quickly ( in this case pins 4, 5, 7, and 48-port Cisco EtherSwitch modules... Model. ) supporting 802.3af is increased by 4 bytes CME can be! Single signaling queue servicing multiple branches larger bandwidth consists of a statically configured 40-bit or 128-bit character key the... Described in RFC 2872, the download process would take about 4.5 minutes 2951 ISRs support one slot for Class-Based!

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