Dialon Demand Routing

1
Dial-on Demand Routing

• Single or Bi-directional Dialing
• If both routers dial
• Either site can initiate a link when there is
  traffic destined for the other router's network
• Both routers could dial at the same time, which
  would result in a busy message
• If dialing is restricted to the SOHO router
• Traffic from the central site destined for the
  SOHO router would fail if the link is not up
• You will avoid busy messages due to "colliding"
  calls

2
DDR cont.

• Dialer maps (Legacy DDR)
• Physical interfaces linked to logical
  configuration
• All B channels share physical interfaces
  configuration
• Dialer profiles
• Separates logical configurations from physical
  configurations
• Separate interfaces can share dialer profiles
• Doesnt waste ISDN B channels

3
Configuring ISDN
Branch
Central
ISDN
Router(config) hostname Branch Branch(config)
enable secret class Branch(config) isdn
switch-type basic-5ess Branch(config) ip route
10.10.10.0 255.255.255.0 bri 0/0 Branch(config)
dialer-list 1 protocol ip permit Branch(config)
int bri0/0 Branch(config-if) ip address
10.10.10.2 255.255.255.0 Branch(config-if)
encapsulation ppp Branch(config-if) dialer
idle-timeout 300 Branch(config-if) dialer map ip
10.10.10.1 name Central 7553001 Branch(config-if)
dialer-group 1 Branch(config-if) isdn spid1
41975530020001
4
Configuring ISDN
Branch
Central
ISDN
Router(config) hostname Branch Branch(config)
enable secret class Branch(config) isdn
switch-type basic-5ess Branch(config) ip route
10.10.10.0 255.255.255.0 bri 0/0 Branch(config)
dialer-list 1 protocol ip permit Branch(config)
int bri0/0 Branch(config-if) ip address
10.10.10.2 255.255.255.0 Branch(config-if)
encapsulation ppp Branch(config-if) dialer
idle-timeout 300 Branch(config-if) dialer map ip
10.10.10.1 name Central 7553001 Branch(config-if)
dialer-group 1 Branch(config-if) isdn spid1
41975530020001
Branch(config) access list 101 deny rip any
any Branch(config) access list 101 permit ip any
any Branch(config) dialer list 1 protocol ip
list 101
5
Troubleshooting ISDN

• show isdn status
• show dialer
• show ip route
• debug isdn q921
• debug isdn q931
• debug dialer events

6
Properly configured ISDN
Router show isdn statusThe current ISDN
Switchtype basic-ni1ISDN BRI0 interfaceLayer
1 StatusACTIVELayer 2 StatusTEI 109, State
MULTIPLE_FRAME_ESTABLISHEDTEI 110, State
MULTIPLE_FRAME_ESTABLISHEDSpid StatusTEI 109,
ces 1, state 8(established)spid1 configured,
spid1 sent, spid1 validEndpoint ID Info epsf
0, usid 1, tid 1TEI 110, ces 2, state
8(established)spid2 configured, spid2 sent,
spid2 validEndpoint ID Info epsf 0, usid 3,
tid 1Layer 3 Status0 Active Layer 3
Call(s)Activated dsl 0 CCBs 0Total Allocated
ISDN CCBs 0
7
Layer 1 issues
Router show isdn statusGlobal ISDN Switchtype
basic-niISDN BRI0 interfacedsl 0, interface
ISDN Switchtype basic-niLayer 1
StatusDEACTIVATEDLayer 2 StatusLayer 2 NOT
ActivatedSpid StatusTEI Not Assigned, ces 1,
state 3(await establishment)spid1 configured,
spid1 NOT sent, spid1 NOT validTEI Not Assigned,
ces 2, state 1(terminal down)spid2
configured, spid2 NOT sent, spid2 NOT validLayer
3 Status0 Active Layer 3 Call(s)Activated dsl
0 CCBs 0The Free Channel Mask
0x80000003Total Allocated ISDN CCBs 0
8
Layer 2 issues
Router show isdn statusGlobal ISDN Switchtype
basic-niISDN BRI0 interfacedsl 0, interface
ISDN Switchtype basic-niLayer 1
StatusACTIVELayer 2 StatusLayer 2 NOT
ActivatedSpid StatusTEI Not Assigned, ces 1,
state 3(await establishment)spid1 configured,
spid1 NOT sent, spid1 NOT validTEI Not Assigned,
ces 2, state 1(terminal down)spid2
configured, spid2 NOT sent, spid2 NOT validLayer
3 StatusTWAIT timer active0 Active Layer 3
Call(s)Activated dsl 0 CCBs 0The Free Channel
Mask 0x80000003Total Allocated ISDN CCBs 0
9
show dialer interface
BRI0 - dialer type ISDNDial String Successes
Failures Last called Last status 0 incoming
call(s) have been screened. BRI0 B-Channel
1Idle timer (120 secs), Fast idle timer (20
secs)Wait for carrier (30 secs), Re-enable (15
secs) Dialer state is data link layer up Dial
reason ip (s6.1.1.8, d6.1.1.1) Interface bound
to profile Dialer0 Time until disconnect 102
secsCurrent call connected 000019Connected to
5773872 (wolfman) BRI0 B-Channel 2Idle timer
(120 secs), Fast idle timer (20 secs)Wait for
carrier (30 secs), Re-enable (15 secs) Dialer
state is idle
10
show ip route
Router show ip route Codes I - IGRP derived, R
- RIP derived, O - OSPF derived, C - connected,
S - static, E - EGP derived, B - BGP derived,
- candidate default route, IA - OSPF inter area
route, i - IS-IS derived, ia - IS-IS, U -
per-user static route, o - on-demand routing, M
- mobile, P - periodic downloaded static
route, D - EIGRP, EX - EIGRP external, E1 - OSPF
external type 1 route, E2 - OSPF external type 2
route, N1 - OSPF NSSA external type 1 route, N2
- OSPF NSSA external type 2 route Gateway of last
resort is 131.119.254.240 to network
129.140.0.0 R 150.150.0.0 4/120 via
131.119.254.6, 00100, Ethernet2R
192.68.132.0 5/120 via 131.119.254.6, 00059,
Ethernet2R 130.130.0.0 2/120 via
131.119.254.6, 00059, Ethernet2
11
debug isdn q921
Router debug isdn q921 Jan 3 145224.475 ISDN
BR0 TX -gt INFOc sapi 0 tei 64 ns 5 nr
2 i 0x08010705040288901801837006803631383835J
an 3 145224.503 ISDN BR0 RX lt- RRr sapi 0
tei 64 nr 6Jan 3 145224.527 ISDN BR0 RX
lt- INFOc sapi 0 tei 64 ns 2 nr 6 i
0x08018702180189Jan 3 145224.535 ISDN BR0 TX
-gt RRr sapi 0 tei 64 nr 3Jan 3
145224.643 ISDN BR0 RX lt- INFOc sapi 0 tei
64 ns 3 nr 6 i 0x08018707Jan 3
145224.655 ISDN BR0 TX -gt RRr sapi 0 tei
64 nr 4LINK-3-UPDOWN Interface BRI01,
changed state to upJan 3 145224.683 ISDN BR0
TX -gt INFOc sapi 0 tei 64 ns 6 nr 4 i
0x0801070FJan 3 145224.699 ISDN BR0 RX lt-
RRr sapi 0 tei 64 nr 7LINEPROTO-5-UPDOWN
Line protocol on Interface BRI01, changed state
to upISDN-6-CONNECT Interface BRI01 is now
connected to 61885 goodieJan 3 145234.415
ISDN BR0 RX lt- RRp sapi 0 tei 64 nr 7Jan
3 145234.419 ISDN BR0 TX -gt RRf sapi 0 tei
64 nr 4
12
debug isdn q931
Router debug isdn q931 TX -gt SETUP pd 8
callref 0x04 Bearer Capability i 0x8890
Channel ID i 0x83 Called Party Number i
0x80, 415555121202RX lt- CALL_PROC pd 8
callref 0x84 Channel ID i 0x89RX lt-
CONNECT pd 8 callref 0x84TX -gt CONNECT_ACK
pd 8 callref 0x04
Outgoing call
Router debug isdn q931 RX lt- SETUP pd 8
callref 0x06 Bearer Capability i 0x8890
Channel ID i 0x89 Calling Party Number i
0x0083, 81012345678902TX -gt CONNECT pd 8
callref 0x86RX lt- CONNECT_ACK pd 8 callref
0x06
Incoming call
13
debug dialer events
Router debug dialer events Dialing cause
Serial0 ip (s172.16.1.111 d172.16.2.22)