Gatekeeper Signaling: LRQ Sequential
For attendant back-up and load-sharing features, you can configure assorted gatekeepers
to account the aforementioned area or technology prefix by sending LRQs to two or more
gatekeepers. Either the LRQs are beatific sequentially to the gatekeepers or to all gatekeepers
at the aforementioned time (blast).
Sequential forwarding of LRQs is the absence forwarding mode. With consecutive LRQ forwarding,
the basic attendant assiduously an LRQ to the aboriginal attendant in the matching
list. The basic attendant again waits for a acknowledgment afore sending an LRQ to
the abutting attendant on the list. If the basic attendant receives an LCF while waiting,
it will abolish the LRQ forwarding process.
If you accept assorted analogous prefix zones, you ability appetite to accede application sequential
LRQ forwarding instead of bang LRQ forwarding. With consecutive forwarding, you can
configure which routes are primary, secondary, and tertiary.
Figure 8-9 shows three gatekeepers to which Attendant A can point. Attendant A,
whose agreement is provided in Example 8-1, will accelerate an LRQ aboriginal to Attendant B.
Gatekeeper B will accelerate a acknowledgment as either an LCF or an LRJ to Attendant A. If Gatekeeper
B allotment an LCF to Attendant A, the LRQ forwarding action will be terminated. If
Gatekeeper B allotment an LRJ to Attendant A, again Attendant A will accelerate an LRQ to
Gatekeeper C. Attendant C will acknowledgment either an LCF or LRJ to Attendant A. Then
Gatekeeper A will either abolish the LRQ forwarding action or alpha the LRQ process
again with Attendant D.
458 Authorized Self-Study Guide: Cisco Voice over IP (CVOICE)
Gateway A
V
ARQ
1 LRQ
GKA GKB
2 LRQ
3 LRQ
GKC
GKD
Gatekeeper A Attendant B
Gatekeeper C
Gatekeeper D
Figure 8-9 Consecutive LRQ
Example 8-1 Consecutive LRQ Configuration
GKA(config)#gatekeeper
GKA(config-gk)#zone bounded GKA cisco.com
GKA(config-gk)#zone alien GKB cisco.com
GKA(config-gk)#zone alien GKC cisco.com
GKA(config-gk)#zone alien GKD cisco.com
GKA(config-gk)#zone prefix GKB 1408555.... seq
GKA(config-gk)#zone prefix GKC 1408555.... seq
GKA(config-gk)#zone prefix GKD 1408555.... seq
Notice the area prefix commands at the basal of the router output. Because sequence
is the absence adjustment for LRQ forwarding, the advantage seq can be included, and sequential
LRQ forwarding will booty place.
Note With consecutive LRQs, there is a anchored timer aback LRQs are sent. Even if
Gatekeeper A gets an LRJ aback anon from Attendant B, it will delay a anchored amount
of time afore sending the abutting LRQ to Attendant C and Attendant D. You can speed
up this action by application the lrq lrj immediate-advance command.