This diagram includes elements that face the larger network only. More specific diagrams of internal networks can be uploaded on other pages.

Dia source can be found here in case trmg is hit by a bus or something. Feel free to request and/or coordinate adds/changes from/with trmg as needed.

Network switching devices have been labeled with letters and trunks labeled with numbers for (hopefully) faster reference.

switch	CLLI	equip. operator
A	OKVLONXH01T	appledash
B	ESCLCAX0DS0	trmg
C	ESCLCAX001T	trmg
D	LBRDILLGAX0	joe_z
E		doppler
F	STJHNFX0DS0	andrew
G	STJHNFX001T	andrew
H	GSORGYATE1T	gewt
I	DRHMNCX001T	techfury90

trunk	CLLI A	equip. operator A	CLLI B	equip. operator B
1	ESCLCAX0DS0	trmg	LBRDILLMDS0	joe_z
2	LBRDILLGAX0	joe_z	(E)	doppler
3	ESCLCAX0DS0	trmg	ESCLCAX001T	trmg
4	ESCLCAX0DS0	trmg	OKVLONXH01T	appledash
5	ESCLCAX0DS0	trmg	STJHNFX0DS0	andrew
6	ESCLCAX0DS0	trmg	GSORGYATE1T	gewt
7	ESCLCAX001T	trmg	STJHNFX001T	andrew
8	ESCLCAX001T	trmg	GSORGYATE1T	gewt
9	ESCLCAX001T	trmg	DRHMNCX001T	techfury90
10	STJHNFX0DS0	andrew	STJHNFX001T	andrew
11	STJHNFX0DS0	andrew	GSORGYATE1T	gewt
12	GSORGYATE1T	gewt	DRHMNCX001T	techfury90

Network Failure Mode Effects Analysis

This section will analyze the effects of single-point failures on the network as it stands now. A single point failure will, often, result in loss of service for one member of the SCDP. Anything more than loss of service to just a single member should be considered a problem that requires fixing, within reason. Loss of service to a single member can, of course, also be protected against at the discretion of that member, but is considered a lesser issue.

Single Trunk Failures

A single trunk failure is a failure that takes out just one trunk or route between two switching devices in the SCDP. The effects of the failures on the overall network including effects due to the current routing plan are analyzed.

1 - ESCLCAX0DS0 (B) to LBRDILLGAX0 (D)

An IAX2 trunk between joe_z and trmg, this link carries nearly the entire traffic outbound from joe_z to the rest of the SCDP. In the event of a link failure here, the network is bifurcated into two smaller networks, one composed of joe_z and doppler, and another composed of the other SCDP members.

Recommendations: improve trunk redundancy with the rest of the SCDP network by adding at least one additional trunk between joe_z and another peer within the SCDP. Ensure the routing plan has failover built in to reroute new calls over the secondary trunk should the primary trunk fail.

2 - LBRDILLGAX0 (D) to CLLIUNKNOWN (E)

An IAX2 trunk between joe_z and doppler, this trunk carries only traffic between joe_z (including tandem traffic) and doppler. This trunk is the sole trunk for inbound traffic to doppler. In the event of a trunk failure, doppler is the only SCDP member affected by the fault. Calls placed to doppler will fail, and doppler will not be able to place calls to the larger SCDP network.

Recommendations: As this failure only results in loss of service to one member, it is considered low priority. At the discretion of doppler, they may wish to increase their number of links to the rest of the SCDP in order to have a secondary path for outbound and inbound traffic.

Single Switch Failures

A single switch failure is a failure that takes out just one switching element in the SCDP. The effects of the failures of the switching devices on the overall network including effects due to the current routing plan are analyzed.

D - LBRDILLGAX0

This is the only SCDP-facing tandem switch in joe_z's network currently. Additionally, it functions as the only tandem to doppler's network. Loss of this switch results in the loss of all traffic between doppler and the greater SCDP and all traffic between joe_z and the greater SCDP, including traffic between joe_z and doppler.

Recommendations: This failure results in loss of service to 2 members of the SCDP. There are multiple ways to go about solving this.

One way is for doppler to establish additional trunking with another switch on the SCDP and setup routing for a primary and secondary link. This would limit the effects of the failure to joe_z's network only.

Another option is for joe_z to establish an additional tandem switch that can be used internally as a secondary path to the greater SCDP. Without additional trunks to doppler, doppler would still lose service without LBRDILLGAX0. At doppler's discretion, they could establish additional trunks to use in the event of a failure of LBRDILLGAX0.

Single Location Failures

A single location failure is a failure that effects all switches and links within a particular physical location. For example, a location failure of trmg's CO would include both ESCLCAXDS0 and ESCLCAX001T, affecting all trunks served by those switches.

A location failure could be as the result of a power outage or (at the present time) an internet service outage at one of the member locations in the SCDP. A location failure is likely to disrupt service to all equipment at that location, but effects to the greater network can be avoided with planning and careful use of redundant trunks to other locations.

joe_z - 563

A failure of all equipment at joe_z's CO, at the present time, would be equivalent to a failure of LBRDILLGAX0 (D). See that section for details.