Hi guys,
It’s really exciting that we are moving to one flexible solution to have the IP
and interface tables separately. Based on this, I have some ideas for the
change of the Traffic Monitor(TM). Actually, the TM have two different purposes
to polling the cache servers. One is to make sure the connectivity is ok, the
other is to query the stat of the interface. The connectivity is actually for
the IP (with port) connectivity, while the stat is for the interface. Since we
will have multiple interfaces and may have multiple IPs for each interface, I
think the polling to the cache server should be like:
1) Check the connectivity of all the configured IPs of the cache server
This function works like the keep alive to make sure all the configured IPs
is reachable.
2) Query the stat for all the configured interfaces of the cache server
This function is to query the interfaces stat, it doesn’t care which IP
will be used to query the stat.
So I suggest the change to the current TM to be like:
1) Separate the current polling of cache servers into two different pollings,
one for the keep alive, the other for the stat query.
For the keep alive polling, we can use some specific url to check if the IP
with port is opened or not; For the stat query, we will reuse the astats
plugin, but need a little change to the uri to support returning multiple
interfaces stat in the same request.
If we don’t separate it, we will have to issue each stat query for each IP,
and all the IPs of one interface will return the same big response, which is
unnecessary, and will bring much more unnecessary load to the ATS and TM. If we
separate it, we could make the keep alive check very light weighted, and also
can use one request to query all the configured interfaces stat. Besides, we
could also use different polling intervals for the keep alive and stat query.
2) The health availability of the cache server will be based on the configured
IPs of the cache server
Currently, we only have the availability of one cache server, but it will
not be enough when we add multiple interfaces and multiple IPs support. We need
record the availability for each configured IP so that if it’s assigned, the
router can check if it can redirect the client request to that assigned IP or
not.
3) The max available bandwidth check should be changed to per interface.
Currently, the max available bandwidth is only for the primary interface of
the cache server, if we have multiple interfaces support, we should check the
bandwidth availability for each interface. If one interface is overload, we
will mark all the IPs of that interface to be unavailable.
4) We will pick up one available IP to query the stat.
Currently, we use the fqdn of the cache server to query the stat, since we
will have multiple IPs, we could pick up one available IP to query.
Best regards,
Neil
On 4/4/18, 1:23 PM, "Nir Sopher" <[email protected]> wrote:
+1
Note that beyond the DB, the change should also be reflected into the
cr-config.
As I see it, a flexible model may be built of the below items:
1 - Edge server.
2- Interface
3. IPs
The Interface (or should it be called "delivery unit") is the element we
redirect the traffic to and which is monitored by the traffic-monitor:
* Each server may have multiple interfaces
* Each interface may have multiple IPs
* Interfaces has priorities (abstraction for primary/secondary)
* Each interface is given a seperate DNS name by the router. Single name
for the multiple IPs.
* Each interface is monitored and reported seperately by the traffic
monitor, including health an stats.
The router "redirect target decision" may look as follows
0. Select cache as we do today taking into account the consistent hash. A
server is in the selection group only if one of its interfaces is found to
be healthy
1. Once we have server selected, select an interface out of all interfaces
of the server with max available priority.
An additional improvement, may assign DS to interfaces instead of servers.
A server serves DS X iff one of its interfaces is assigned to the DS.
Nir
On Apr 4, 2018 6:56 AM, "Zhilin Huang (zhilhuan)" <[email protected]>
wrote:
Updated the DB schema in section 3.1.1.4
Thanks,
Zhilin
On 04/04/2018, 11:02 AM, "Zhilin Huang (zhilhuan)" <[email protected]>
wrote:
Good points. I am happy to make this change in the design doc.
Thanks,
Zhilin
On 03/04/2018, 8:17 PM, "Eric Friedrich (efriedri)" <[email protected]>
wrote:
I would prefer a consistent way to store all interface and IP
address information. Its good database design practice to store similar
information in similar tables (i.e. all IP info in 1 table) rather than
keep some IPs in the server table and some IPs in another table.
I also think this refactoring will give us greater flexibility for
more changes in the future. Outside of this particular use case, we might
have additional features like sharing edges between public/private networks
or having multiple (equal priority) streaming interfaces on a cache.
These future features would be easier if the interface data and IP
data is all organized into separate tables.
I’d also like to see the delivery service to IP mapping be a many
to many mapping in the DB. For this particular feature we will only assign
a single IP (and we can restrict that in the API if we want), but I am near
certain that in the future we would like the ability to assign a DS to
multiple IPs on the same cache.
—Eric
> On Apr 3, 2018, at 2:42 AM, Zhilin Huang (zhilhuan) <
[email protected]> wrote:
>
> Hi Mark,
>
> Thanks for your comments. Please check my reply in another thread:
>
> If we all agreed to use unified tables for all IPs and/or
interfaces: primary, management, secondary, then there need to be two
tables: IP and interface.
> And in the server table, we need to replace the original
"interface_xxx", "ip_xxx", "ip6_xxx" fields with a "primary_ip_id" field.
And do similar things to management IP.
>
> Thanks,
> Zhilin
>
>
> On 03/04/2018, 7:08 AM, "Mark Torluemke" <[email protected]>
wrote:
>
> I would support an 'interfaces' table (adding some sort of a
'type' column)
> that would include moving the management and lights out
management
> interfaces to that table as well.
>
> Cheers,
> Mark
>
> On Mon, Apr 2, 2018 at 2:39 PM, Nir Sopher <[email protected]>
wrote:
>
>> Hi Zhilin,
>>
>> I took a quick look into the spec. Hope to have the opportunity
to dive
>> deeper into it soon so we can further discuss it.
>>
>> For now I have a 2 questions.
>> In the spec, you refer to "secondary interfaces", and you have a
list of
>> secondary interfaces added.
>> IIUC the secondary interfaces are used as long as they are
available, and
>> when down, you move to the primary interface.
>>
>> Why not, instead of holding a secondary interfaces table, move
all
>> interfaces to a separate table? Primary and secondary.
>> For each interface you can hold:
>>
>> - Server id
>> - name (e.g. eth0)
>> - IPv6
>> - IPv4
>> - Priority (Integer as flexible as you wish: e.g. "1" for
"secondary",
>> "2" for "primary" in your example,)
>>
>>
>> Additionally, it is not clear to me what happens if one of the
interfaces
>> fails?
>> Does every interface has a unique DNS name? If an interface
fails, are
>> redirects
>> sent only to the available (secondary) interfaces?
>>
>> Thanks,
>> Nir
>>
>>
>> On Mon, Apr 2, 2018 at 10:21 AM, Zhilin Huang (zhilhuan) <
>> [email protected]
>>> wrote:
>>
>>> Hi Guys,
>>>
>>> This was originally posted in another discussion. Resend this
in a
>>> standalone topic to catch more awareness. The link for the
design doc:
>>>
https://docs.google.com/document/d/1vgq-pGNoLLYf7Y3cu5hWu67TUKpN5hucrp
>>> -ZS9nSsd4/edit?usp=sharing
>>>
>>>
>>> Short summary for the feature design:
>>> ---
>>> There is feature request from market to add secondary IPs
support on edge
>>> cache servers, and the functionality to assign a delivery
service to a
>>> secondary IP of an edge cache.
>>>
>>> This feature requires Traffic Ops implementation to support
secondary IP
>>> configuration for edge cache, and delivery service assignment to
>> secondary
>>> IP.
>>>
>>> Traffic Monitor should also monitor connectivity of secondary
IPs
>>> configured. And Traffic Router needs support to resolve
streamer FQDN to
>>> secondary IP assigned in a delivery service.
>>>
>>> Traffic Server should record the IP serving client request. And
should
>>> reject request to an unassigned IP for a delivery service.
>>>
>>> This design has taken compatibility into consideration: if no
secondary
>> IP
>>> configured, or some parts of the system has not been upgraded
to the
>>> version supports this feature, the traffic will be served by
primary IPs
>> as
>>> before.
>>> ---
>>>
>>> Much appreciated and welcome to any comments. If no major
objections, we
>>> planned to start coding this week.
>>>
>>> Thanks,
>>> Zhilin
>>>
>>>
>>
>
>
