IP Telefoni. DHCP Options VLANs

Transcription

1 IP Telefon DHCP Optons VLANs

2 The Csco IP Phone attempts to contact the frst call processng server (the prmary server) lsted n ts confguraton fle to regster. If ths fals, the IP phone moves to the next server n the confguraton fle. Ths process contnues untl the IP phone regsters successfully or the lst of call processng agents s exhausted. Understandng the Csco IP Phone Boot Process The Csco IP Phone connects to an Ethernet swtchport. If the IP phone and swtch support PoE, the IP phone receves power through ether Csco-propretary PoE or 82.af PoE. As the Csco IP Phone powers on, the Csco swtch delvers voce VLAN nformaton to the IP phone usng CDP as a delvery mechansm. The Csco IP Phone now knows what VLAN t should use. The Csco IP Phone sends a DHCP request askng for an IP address on ts voce VLAN. The DHCP server responds wth an IP address offer. When the Csco IP Phone accepts the offer, t receves all the DHCP optons that go along wth the DHCP request. DHCP optons nclude tems such as default gateway, DNS server nformaton, doman name nformaton, and so on. In the case of Csco IP Phones, a unque DHCP opton s ncluded, known as Opton 15. Ths opton drects the IP phone to a TFTP server. After the Csco IP Phone has the IP address of the TFTP server, t contacts the TFTP server and downloads ts confguraton fle.

3 DHCP (Dynamc Host Confguraton Protocol) En DHCP servers funkton er at styre og konfgurere TCP/IP opsætnngen på computere/klenter som anmoder om det. DHCP serveren letter det admnstratve arbejde betydelgt, det der kke manuelt tldeles IP adresser mv. Desuden kan den samme adresse kke lejes ud 2 gange på samme td, dvs. at man kke kan få adresse konflkt. En DHCP server kan konfgurere DHCP klenter med mange forskellge parametre som fx: En IP adresse Subnet maske Gateway adresse Adressen på en eller flere DNS servere WINS servere, proxy server osv. KlentDHCP 1. DHCP-Dscover 2. DHCP-Offer. DHCP-Request 4. DHCP-Ack Servere

4 DHCP (Dynamc Host Confguraton Protocol) DHCP-Dscover Klent anmoder om konfguraton fra en DHCP-server DHCP-Offer Servere tlbyder IP-adresse og øvrge standard opsætnnger DHCP-Request Klent vælger server og bekræfter de parametre serveren leverede DHCP-Ack Serveren accepterer valget KlentDHCP 1. DHCP-Dscover 2. DHCP-Offer. DHCP-Request 4. DHCP-Ack Servere 4

5 DHCP Clent DHCP Clent DHCP example DHCP lease pool on server: IP address range: Subnet mask: DNS server: Default gateway: Net: /24 ROUTER Internet DHCP Server Statc IP address DHCP Clent 1. DHCP-Dscover 2. DHCP-Offer DHCP Server(s). DHCP-Request DNS server DHCP-Ack Network

6 DHCP optons Wndows DHCP server optons confguraton example TFTP servers are often used to store IP phones confguraton fles.

7 GHI PQRS JKL TUV 7 GHI PQRS JKL TUV 7 IP TELEPHONY AND VOICE VLAN

8 GHI PQRS JKL TUV 7 GHI PQRS JKL TUV GHI PQRS 7 JKL TUV 7 GHI PQRS JKL TUV 7 IP Telephony In a normal DHCP voce Server call 5 Call packets Manager per second s sent n each drecton. One packet each.2 second Router The VPN connects the companes branches The Call Manager s a nto voce one call bg Processng IP network. system The allowng voce QoS gateway IP (Qualty phones connects of to Servce) call each the needed prvate other to ensure IP and phone drect good system calls voce to to and qualty the from global n PSTN conversatons PSTN (Publc Swtched Telephone Network) VPN wth QoS Voce Gateway Voce PSTN Router QoS Qualty of Servce VPN Vrtuel Prvate Network. (MPLS) PSTN Publc Swtched Telephone Network

9 IP Telephony IP telephony s an nstant servce Voce packet stream between phones Normaly 5 packets per second To ensure good voce qualty, voce packets should be transferred between phones Wth low delay ( < 15mS) Wth lttle jtter (< ms) Jtter s varable delay between packets n Wth lttle packet loss (< 1%)

10 IP Telephony VoIP best practce s separatng voce and data traffc n the network Enhancng securty not mxng VoIP and data Troubleshootng smplfed Easer to deploy Qualty of Servce Two ways of separatng data and voce Two physcal networks One physcal network wth separate VLAN s for voce and data

11 IP Telephony Two physcal networks Expensve 2 x Devces, 2 x cablng and 2 x VPN s Easy to ensure good voce qualty One physcal network Two logcal networks one for voce one for data Usng a data-vlan and a voce-vlan Cheaper More dffcult to ensure voce qualty Need end-to-end qualty of servce confgured

12 VLAN Revew Vrtual Local Area Network Swtch ports belong to a VLAN Devces on same VLAN can communcate Swtch ports confgured as trunks can exchange VLAN traffc between swtches VLAN 1 VLAN 2 TRUNK VLAN capable swtch 82.1Q 82.1Q VLAN capable swtch VLAN 1 VLAN 1 VLAN 2 VLAN 2

13 Voce VLAN opton 1 Traffc separated physcally between swtch and users desk One cable and one swtch port for users PC One cable and one swtch port for users IP Phone Expensve n cablng and swtches VLAN 1 VLAN 2 Data Voce TRUNK VLAN capable swtch 82.1Q 82.1Q VLAN capable swtch VLAN 1 VLAN 1 VLAN 2 VLAN 2

14 Voce VLAN opton 2 Traffc IP phone ethernet separated port connects logcally to between swtch and Swtch users n rack desk closet typcally through RJ45 wall plug. Use IP phones wth bult-n trunk capablty Buld n three-port swtch n the IP Phone One phone swtch port n used as trunk One phone swtch port used by the IP phone t self One phone swtch port used to connect the PC IP phone ethernet port connects to Users PC

15 Voce VLAN opton 2 Data traffc carred n VLAN 1 Voce traffc carred n VLAN 2 VLAN 1 VLAN 2 Data Voce TRUNK VLAN capable swtch VLAN capable swtch VLAN 1 VLAN 1 VLAN 2 VLAN 2

16 PoE Power over Ethernet Most IP phones are powered by 48 Vdc Many IP phones can get power from External power supply connected to mans From swtches capable of delverng power PoE or Power over Ethernet Pcture below s a partal prntout from a PoE capable swtch