ISDN

ISDN

Standards series,
  • E - ISDN over telecom network
  • I - Concepts and Interfaces
  • Q - Switching and signaling
 
E.163 PSTN numbering plan
E.164 ISDN Addressing Standard
I.400 User Network Interface
ç ISDN Reference Points
Q.921 LAPD (Layer 2)
Q.931 ISDN Layer 3

Terminals - Functional Groups

  • Terminal Equipment / Endpoint
      • Type 1 - ISDN ready
      Type 2 - Not ISDN ready
  • Terminal Adapter (for type 2 endpoints)
  • Network Termination Point
      • NT2
      NT1 (Local Loop Terminator)

Reference Points (I.411)

  • R - Regular - between endpoint and terminal adapter
  • S - Special - between endpoint / terminal adapter and NT2
  • T - Termination - between NT2 and NT1
  • U - unpowered - between NT1 and Telco
S and T are electrically the same

Channels

logical divisions
  • B - bearer, clear channel only data, 64 Kbps
  • D - signaling, 16Kbps (BRI) or 64 Kbps (PRI)

Basic Rate Interface

2B + D
144Kbps = 64 + 64 + 16
Service Profile ID (SPID) is required in NA, serves as a password, numerical string assigned by the telco to each B channel
10 digit phone number + 2 digit sharing terminal ID (01-32) + 2 digit terminal ID (01-08)

Primary Rate Interface

NA: 23B + D (T1)
EU: 30 B + D (E1)
D is also 64Kbps

Encapsulations

B Channels
D Channels
HDLC (Default, no multi-link)
Q.921
PPP
Q.931
ISDN Switch-Type (Global or Interface)

Dial On Demand Routing (DDR)

int bri 0
	ip address 172.20.1.1.2 255.255.255.252
	isdn switch-type basic-net3
	isdn spid1 111
	dialer-group 1
	encapsulation ppp
	ppp multilink
	dialer load-threshold 1 either
	dialer map ip 172.20.1.1 broadcast 4802222222
	dialer idle-timeout 120
	no shut
	
dialer-list 1 protocol ip permit

show isdn status

show dialer

debug dialer
 
Floating static route option
ip route 192.168.2.0 255.255.255.0 172.20.1.1 250
 
Backup Interface option
router ospf 1
	network 172.20.1.2 0.0.0.0 area 0
	
int s0
	backup interface bri 0
	backup delay 3 15
 
OSPF disable hello packets option
router ospf 1
	network 172.20.1.2 0.0.0.0 area 0
	
int bri 0
	ip ospf demand-circuit
Does not work if any ASBR in OSPF network, put ISDN in own Stub area
 
Dialer watch option
dialer watch-list 1 ip 172.16.4.0 255.255.255.0

int bri 0
	dialer watch-group 1
	dialer map ip 172.16.4.0 4802222222
Needs exact match, can’t use summary