ISDN PRI back-to-back

To emulate a PSTN router, we need a back to back E1 connection and the obviously the first step would be the cable connecting both routers. Here, the idea is to connect HQ Router with PSTN router and therefore the crossover cable needs to be made.

Following should be the PIN Configuration; RJ-48 Connector to RJ-48 Connector (Crossover) Pinout:

1 RX Ring - -> 4 TX Ring -
2 RX Tip + -> 5 TX Tip +
4 TX Ring - -> 1 RX Ring -
5 TX Tip + -> 2 RX Tip +

When connected, both 1MFT-E1 cards have immediatly turned on the "CD" Carrier Detect light,

The basic configuration to emulate a PSTN Pri will be:

PSTN_RTR#

network-clock-participate wic 0

controller E1 0/0/0
clock source internal ---- the "pstn network" side must provide clock
pri-group timeslots 1-31

interface Serial0/0/0:15

no ip address

encapsulation hdlc

isdn switch-type primary-net5

isdn protocol-emulate network ---- this is the PSTN-emulated side ‘Service Provider’

isdn incoming-voice voice

no cdp enable

HQ_RTR#

network-clock-participate wic 0

controller E1 1/0/0
pri-group timeslots 1-31

interface Serial1/0/0:15
no ip address
encapsulation hdlc
isdn switch-type primary-net5
isdn incoming-voice voice
no cdp enable
!

Reference: http://www.juniper.net/techpubs/hardware/m40/m40-hwguide/html/pinout4.html

http://www.techexams.net/forums/ccvp/31284-back-back-pri-am-i-missing-something.html

http://ccvp.org/modules/newbb/viewtopic.php?topic_id=63&forum=19

http://rizzitech.blogspot.com/2009/02/wvic-1mft-e1-back-to-back-connection.html

https://supportforums.cisco.com/message/3135483

Default DHCP lease and CUCM 7.0 DHCP rebinding

Default DHCP Lease
Configuring the Address Lease Time

By default, each IP address assigned by a DHCP server comes with a one-day lease, which is the amount of time that the address is valid. To change the lease value for an IP address, use the following command in DHCP pool configuration mode:

Command	Purpose
Router(config-dhcp)# lease {days [hours][minutes] | infinite}	Specifies the duration of the lease. The default is a a one-day lease.

http://cisco.biz/en/US/docs/ios/12_0t/12_0t1/feature/guide/Easyip2.html#wp22915

CUCM 7.0 DHCP rebinding

Rebinding Timer (T2) Expires

If the client receives no reply from the server, it will remain in the RENEWING state, and will regularly retransmit the unicast DHCPREQUEST to the server. During this period of time, the client is still operating normally, from the perspective of its user. If no response from the server is received, eventually the rebinding timer (T2) expires. This will cause the client to transition to the REBINDING state, the T2 timer is set to 87.5% (7/8ths) (as per cisco’s recommendation it should be 75% of the lease time) of the length of the lease.

Client Sends DHCPREQUEST Rebinding Message

Having received no response from the server that initially granted the lease, the client “gives up” on that server and tries to contact any server that may be able to extend its existing lease. It creates a DHCPREQUEST message and puts its IP address in the CIAddr field, indicating clearly that it presently owns that address. It then broadcasts the request on the local network.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/7_1_2/ccmcfg/b02dhsrv.html