Intel SIU520 SS7 manual Failure of Routes, Link

Building Fault-tolerant SS7 Systems Using the Intel® NetStructure™ SIU520 SS7 Signaling Gateway Application Note

A) Load sharing between link set 0 and link set 1 under normal

Link Set id 0

STPA

		id	0,	slc	0
	Link
					Point Code
SIU520					0x200	SSP/SCP

	Link
	id
Point Code	1,	slc	0
					Point Code
				STPB
0x100
					0x400
	Link Set id 1
				Point Code
				0x300

B)Traffic sent over link set 1 under failure of STP

Link Set id 0

		id	0,	slc	0
	Link
SIU520							SSP/SCP
	Link	id	1,	slc	0
Point Code
							Point Code
0x100						STPB
							0x400
	Link Set id 1					Point Code
						0x300

Figure 4. SIU520 Connected to Mated STP Pair Providing Route Resiliency

Failure of Routes

Problem — With a single route to a destination point code (DPC), service can be disrupted if all the links of the link set used to reach that signaling node fail. Route failover is a standard MTP3 operation which does not require any specific action from the user application.

Solution — To eliminate this single point of failure, an alternative link set can be provided in the SIU520 system configuration to reach the same DPC. Route failover is a standard MTP3 operation which does not require any specific action from the user application.

Note: When an alternative route to a given DPC is

defined in an SIU520 configuration file, a choice must be made between two different traffic modes: load sharing or failover. In load-sharing mode, traffic sent towards the remote signaling point is shared between the two link sets. In failover mode, all traffic sent towards the remote signaling point will normally be sent using the primary link set, unless this link set fails, in which case the traffic will use the alternative link set. See the Intel NetStructure SIU520 Developer’s Manual for more information on the selection of traffic mode in the MTP_ROUTE command.

Details — This example (see Figure 4) shows two link sets (each containing one link) being used in load-sharing mode to reach destination point code 0x400.

*MTP_LINKSET <linkset_id> <adjacent_spc> <num_links> <flags> <local_spc> <ssf> MTP_LINKSET 0 0x200 2 0x0000 0x100 0x08

MTP_LINKSET 1 0x300 2 0x0000 0x100 0x08

*MTP_LINK <link_id> <linkset_id> <link_ref> <slc> <bpos> <blink> <bpos2> *<stream> <timeslot> <flags>

MTP_LINK 0 0 0 0 0 0 0 0 16 0x0006 MTP_LINK 1 0 1 1 0 1 0 1 16 0x0006 MTP_LINK 2 1 0 0 0 2 0 2 16 0x0006

MTP_LINK 3 1 1 1 0 3 0 3 16 0x0006

*MTP_ROUTE <dpc> <linkset_id> <user_part_mask> <flags> <second_ls> <pc_mask> MTP_ROUTE 0x400 0 0x0020 0x0003 1 0x00000000

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