Wow. So you pointed out a flaw in the provider network. Presumably, they were hosting other customers with the same setup; so how in the world was it working for the others? Or maybe you are the beta tester?
On Thu, Mar 15, 2018 at 9:54 AM Ed Leatherman <ealeather...@gmail.com> wrote: > Follow-up for posterity.. > > I had a feeling this was the case but got some confirmation from TAC: > "This is working as designed when this is an incoming call, the reason > why it works that way is because on the incoming leg the call comes from 1 > specific IP address, and if CUBE does a DNS query for SRV it might resolve > a different IP address than the one where INVITE is coming from and might > cause inbound calls to fail. Instead, if CUBE does DNS query for A record > it will resolve one specific IP address." > > > The service provider changed their SBC to send an IP address in the > Contact field URI which resolved the issue. > > > Ed > > On Thu, Mar 8, 2018 at 2:16 PM, Ed Leatherman <ealeather...@gmail.com> > wrote: > >> >> Follow-up to this SRV/CUBE topic.. >> >> Outbound calls work fine with this setup (after I enabled ip >> domain-lookup ;-) ) >> >> For inbound calls, the service provider is using the hostname for the SRV >> record (peer.isc.lumos.net) in the contact field of the invite. >> Apparently, CUBE only does an A record lookup on that field? >> >> 022206: Mar 8 13:44:04 est: >> //25051/829EEEDD9B28/SIP/Info/verbose/4608/sipSPIProcessContactInfo: >> Previous Hop peer.isc.lumos.net:5060 >> ... >> 022210: Mar 8 13:44:04 est: >> //-1/xxxxxxxxxxxx/SIP/Info/info/8192/sip_dns_type_a_aaaa_query: DNS query >> for peer.isc.lumos.net and type:1 >> 022211: Mar 8 13:44:04 est: >> //-1/xxxxxxxxxxxx/SIP/Error/sip_dns_type_a_query: >> TYPE A query failed for peer.isc.lumos.net >> 022212: Mar 8 13:44:04 est: //-1/xxxxxxxxxxxx/SIP/Error/_send_dns_fail: >> DNS Query for peer.isc.lumos.net failed >> >> CUBE is basically shutting down the call saying it can't resolve the >> contact field. If I put a local host entry for that name using their >> currently active SBC, inbound calls work. Shouldn't CUBE be doing a SRV >> lookup here, or should the service provider send me an hostname instead of >> an SRV in this field? >> >> >> >> >> On Tue, Mar 6, 2018 at 2:25 PM, Anthony Holloway < >> avholloway+cisco-v...@gmail.com> wrote: >> >>> Just so you know, they're not going to know if you use SRV records or >>> not, or host records for that matter. They probably only care about two >>> things: >>> >>> 1) They control which peers you send traffic to via DNS updates >>> >>> 2) They receive the proper/expected host portion in your traffic to them >>> >>> For all intents and purposes, the inclusion of a name in the host >>> portion of a SIP URI is separate from the DNS query. >>> >>> The fact that you point your system at a name (or IP for that matter) >>> and that it then becomes the RHS of the URI is nice, but not required. >>> >>> Therefore, if you ask them to commit to telling you about IP address >>> changes completely negates their desire to use SRV records. Just say'n. >>> >>> On Tue, Mar 6, 2018 at 6:30 AM Ed Leatherman <ealeather...@gmail.com> >>> wrote: >>> >>>> Thanks Anthony, That was spot on what I was trying to figure out. I've >>>> been using server-groups up until now (and will continue on the CUCM facing >>>> side), the service provider is forcing the change on the side facing them. >>>> >>>> Loren: That's an interesting idea to lock in the host resolution on the >>>> CUBE itself, but in this case I think it might set me up for an outage if >>>> the service provider changes their IP Addressing. Maybe I can get them to >>>> commit to telling me before they change those.. >>>> >>>> On Mon, Mar 5, 2018 at 2:31 PM, Anthony Holloway < >>>> avholloway+cisco-v...@gmail.com> wrote: >>>> >>>>> Loren, >>>>> >>>>> Just out of curiosity, why didn't you just use session server groups? >>>>> Based on the config you shared, it looks like it would achieve the same >>>>> thing, but with less config, and not adding in the DNS stack within IOS. >>>>> >>>>> Ed, >>>>> >>>>> *Note, you cannot use DNS in server groups, so it's one or the other. >>>>> >>>>> I also think it's important to know that the IOS code is written such >>>>> that it will look for SRV records first, and then fallback to looking for >>>>> an A (host) record once the DNS timeouts. >>>>> >>>>> E.g., >>>>> >>>>> You enter "session target dns:collab.domain.com" >>>>> >>>>> IOS looks for _sip._udp.collab.domain.com SRV record first, timesout, >>>>> then looks for collab.domain.com host record second. >>>>> >>>>> *Note that the outgoing session transport on IOS is UDP by default, >>>>> unless you change it to TCP with the command "session transport tcp" at >>>>> the >>>>> "voice service voip" level, or at the dial-peer level. So, having a >>>>> _sip._tcp SRV record on your CUBE would create a confusing scenario. >>>>> Contrast this with the incoming connection, which can be either. However, >>>>> SRV records, like Loren is showing, are for outbound connection >>>>> establishments. >>>>> >>>>> I have not done an extensive amount of testing here, but I would be >>>>> curious to know if IOS handles the TTL for the DNS record correctly, or if >>>>> it queries DNS for every setup like how that one defect was hitting CUCM >>>>> SIP trunks for a while there. I looked for "TTL" in the CVP Config guide, >>>>> but it didn't say. >>>>> >>>>> On Mon, Mar 5, 2018 at 11:19 AM Loren Hillukka <lchillu...@hotmail.com> >>>>> wrote: >>>>> >>>>>> You can have your gw query your DNS server, and you have to add SRV >>>>>> records to your central DNS server (like with the jabber entries required >>>>>> to get jabber sign-in to work). >>>>>> >>>>>> Here’s the example of doing local DNS to static entries on the >>>>>> gateway itself, from the CVP 10 config guide. CVP is where I first >>>>>> started >>>>>> doing dns srv on the local gateway, as I preferred breaking the call >>>>>> center >>>>>> myself instead of having the AD/DNS teams do it for me without me knowing >>>>>> ;-) >>>>>> >>>>>> =========== >>>>>> >>>>>> You can also configure the Gateway statically instead of using DNS. >>>>>> The following example shows how both the A and SRV type records could be >>>>>> configured: >>>>>> >>>>>> ip host cvp4cc2.cisco.com 10.4.33.132 >>>>>> >>>>>> ip host cvp4cc3.cisco.com 10.4.33.133 >>>>>> >>>>>> ip host cvp4cc1.cisco.com 10.4.33.131 >>>>>> >>>>>> For SIP/TCP: >>>>>> >>>>>> ip host _sip._tcp.cvp.cisco.com srv 50 50 5060 <50%2050%205060> >>>>>> cvp4cc3.cisco.com >>>>>> >>>>>> ip host _sip._tcp.cvp.cisco.com srv 50 50 5060 <50%2050%205060> >>>>>> cvp4cc2.cisco.com >>>>>> >>>>>> ip host _sip._tcp.cvp.cisco.com srv 50 50 5060 <50%2050%205060> >>>>>> cvp4cc1.cisco.com >>>>>> >>>>>> For SIP/UDP: >>>>>> >>>>>> ip host _sip._udp.cvp.cisco.com srv 50 50 5060 <50%2050%205060> >>>>>> cvp4cc3.cisco.com >>>>>> >>>>>> ip host _sip._udp.cvp.cisco.com srv 50 50 5060 <50%2050%205060> >>>>>> cvp4cc2.cisco.com >>>>>> >>>>>> ip host _sip._udp.cvp.cisco.com srv 50 50 5060 <50%2050%205060> >>>>>> cvp4cc1.cisco.com >>>>>> >>>>>> ============ >>>>>> >>>>>> Then your dial-peer would have session target dns:cvp.cisco.com which >>>>>> would point to the SRV record, which would use the weight/priority values >>>>>> to choose the final host, and resolve the selected host to an IP using >>>>>> the >>>>>> normal "ip host name x.x.x.x" entry >>>>>> >>>>>> >>>>>> Loren >>>>>> >>>>>> On Mar 5, 2018, at 10:15 AM, Ed Leatherman <ealeather...@gmail.com> >>>>>> wrote: >>>>>> >>>>>> Hi everyone, >>>>>> >>>>>> Hopefully a quick question - in a dial-peer on CUBE (16.3.5) how does >>>>>> session target dns: resolve to an IP? I've never used DNS as target >>>>>> before >>>>>> for this. >>>>>> >>>>>> Does CUBE just do a query for the A record by default, or does it do >>>>>> a SRV query by default? I have a SIP provider that wants to start using >>>>>> SRV >>>>>> for their SBC(s) and I'm researching how to setup my end in IOS. If it >>>>>> doesn't query SRV default, where do I toggle that behavior? >>>>>> >>>>>> The command reference just says "Configures the host device housing >>>>>> the domain name system (DNS) server that resolves the name of the dial >>>>>> peer >>>>>> to receive calls." >>>>>> >>>>>> I've found the knob to tell it what SRV format to use in the sip-ua >>>>>> section. >>>>>> >>>>>> Thanks! >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Ed Leatherman >>>>>> >>>>>> _______________________________________________ >>>>>> cisco-voip mailing list >>>>>> cisco-voip@puck.nether.net >>>>>> https://puck.nether.net/mailman/listinfo/cisco-voip >>>>>> >>>>>> _______________________________________________ >>>>>> cisco-voip mailing list >>>>>> cisco-voip@puck.nether.net >>>>>> https://puck.nether.net/mailman/listinfo/cisco-voip >>>>>> >>>>> >>>> >>>> >>>> -- >>>> Ed Leatherman >>>> >>> >> >> >> -- >> Ed Leatherman >> > > > > -- > Ed Leatherman > _______________________________________________ > cisco-voip mailing list > cisco-voip@puck.nether.net > https://puck.nether.net/mailman/listinfo/cisco-voip >
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