[cisco-voip] Expressway cluster algorithm

[Ryan Huff]

SRV weights and priorities do influence the selection, but do not guarantee. The accepting peer can pass to the other peer if the other peer is less utilized.

Sent from my iPhone

On Jan 23, 2019, at 16:35, Lelio Fulgenzi <lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>> wrote:

Gotcha. IIRC, you can’t put weight on traversal neighbours.

So you can use dns srv record weights to pick the C out or the E in, but once inside the cluster picking the next hop E (or C) is round robin.

Interested to hear comments.

-sent from mobile device-

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On Jan 23, 2019, at 4:17 PM, Ryan Huff <ryanhuff at outlook.com<mailto:ryanhuff at outlook.com>> wrote:

I’m trying to guarantee an active/passive use case; so maintenance mode would achieve that (or shutting one side down), but would require manual intervention, and be as clunky of a work-a-round as it gets for a runtime solution.

-Ryan

On Jan 23, 2019, at 16:00, Lelio Fulgenzi <lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>> wrote:

I’m going to read the responses, but when I opened a TAC case, the engineer explained that there were at least two selection processes in play, which C (or E) to pick, then which neighbour to pick for the traversal.

She said, if you want to be 100% sure during troubleshooting, that you are testing a particular path, you want to put the nodes you don’t want to use into maintenance mode.

Made sense to me at the time.

-sent from mobile device-

Lelio Fulgenzi, B.A. | Senior Analyst
Computing and Communications Services | University of Guelph
Room 037 Animal Science & Nutrition Bldg | 50 Stone Rd E | Guelph, ON | N1G 2W1<x-apple-data-detectors://1/0>
519-824-4120 Ext. 56354<tel:519-824-4120;56354> | lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>

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On Jan 23, 2019, at 3:19 PM, Ryan Huff <ryanhuff at outlook.com<mailto:ryanhuff at outlook.com>> wrote:

Can anyone explain or cite the documents that define the algorithm used to determine which Expressway node in a given cluster is selected to process a call.

You can influence the selection with DNS SRV priority and weight, but does not appear to guarantee which cluster node is selected each time.

Thanks,

Ryan
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