path/association retransmit in "show cs7 asp detail"

Unanswered Question
Aug 17th, 2009

Hi, all

I wonder exact meaning of the path retransmit and assoc retransmit in "show cs7 asp detail"


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SG1#sh cs asp detail

ASP name: MTS_A Type: SUA

Availability: enabled ASP id: n/a

SCTP association state: established Association id: 0xA1010009

AS name: MTS ASP state: active Mate state: active

Traffic mode: ldshr bnd, wt: 1 , dist: no

Active Time: 1w5d

Configured remote port: 17003 Actual remote port: 17003

Configured remote ip addresses: 10.7.53.11

10.7.54.11

Actual remote ip addresses: 10.7.53.11 State: active (effective prim)

Local port: 17003

Offload to linecard: Yes Slot: 10 1 AspVipId: 101

ASP protocol class capability: class 0, class 1

ASP interworking with SS7 networks capability: ASP

Local receive window: 64000 Cumulative sack timeout: 200 ms

Assoc retrans: 10 Path retrans: 4

Max init retrans: 8 Max init RTO: 1000 ms

Minimum RTO: 1000 ms Maximum RTO: 1000 ms

Bundle status: on Bundle timeout: 5 ms

Keep alive status: true Keep alive timeout: 30000 ms

SCTP congestion level: 0 SCON congestion level: 0

Unordered priority: equal Transmit queue depth: 1000

Initial cwnd: 3000 Idle cwnd rate: 50

Retrans cwnd rate: 50 Retrans cwnd mode: RFC

FastRetrans cwnd rate: 50

========================================


I think "Path retrans = 4" means time of re-try for each path(primary path, secondary path)


and "Assoc retrans = 10" means time of re-try for association.


if assocation has primary and secondary path(it has two paths)and both path is not available in the far-end.


ITP will try to transmit the chunk(packet) to SEP(Signaling End Point)

first it try into the primary path => would be fail because the far-end down.

second it try into the secondary path => would be fail because the far-end down.


above operation will repeat 4 times.

then itp(SG:signaling gateway) will knows every path is not available.


then what is the "Assoc retrans = 10", is it the sum of the fail(primary path fail + secondary path fail)


primary path fail = 4

secondary path fail = 4

association fail = 8 (as I think!!)


what is the exact meaning of "the Assoc retrans = 10"??


who knows about this?


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scpage Mon, 08/24/2009 - 12:15

Your assumption is bascially correct.

Pathretrans is per destination address.

Association retrans is when the ASP is declared inactive.


Sections 8.1 and 8.2 do a great job of explaining these retransmission counters...

Section 15 lists recommended settings for these values...


http://www.rfc-editor.org/rfc/rfc4960.txt


Now, ITP defaults to 4 per dest and 10 for the association...which is ok as well because ITP declares ASP inactive either when there is no active addresses or when assoc retransmit value is reached.

They left these values as the default because before initial config, the ITP is not aware of how many peers will be in the multihome config and these defaults will be ok in most cases.




Sanghee Han Mon, 08/31/2009 - 22:47

thanks for your help.

and sorry for last answer

(I am back vacation yesterday :))

I'm going to read rfc4960 more detail.


Thanks again.


Sanghee Han Mon, 08/31/2009 - 23:44

Now, cisco itp defaults to 4 per dest and 10 for the association.

if we connects the ASP using multi-homing(primary path and secondary path, just 2 paths)

and when far-end primary and secondary ip address are not available, in this situation primary transmit fail will be 4 times until its path.max.retrans.


like the preceding, secondary transmit fail will be 4 times until its path.max.retras.


then ITP detects both paths(primary and secondary)are not available.

so it declare that association is not avail.

so association.max.retrans(10 times) doen't effect in this case.

am I right?

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