Yes, the hairpinning is unavoidable with single-port. Great description
by the way. It never sat right with me, but I don't have an objective
reason to not like it.
Personally I'm going to populate the SFP+ slot and use a single 10G
fiber.
------ Original Message ------
From: "Nathan Anderson" <[email protected]>
To: "[email protected]" <[email protected]>; "Tristan Johnson"
<[email protected]>
Sent: 1/31/2017 9:48:55 PM
Subject: Re: [Telrad] Setting up EPC
The single-port method is what Telrad recommends for centralized EPC
deployments, and multi-port is (the way I read the docs) only
recommended/intended for EPC-at-each-site deployments. (You can make
it work with centralized EPC, but there are many indicators that this
feature was never intended to work this way.)
But the single-port method will inevitably always have some traffic
hairpinning occur, which is the main reason why I don't like it. It
doesn't matter if you are routing or bridging between your Compacts and
your BreezeWay: the user traffic comes in on the PDN VLAN to the EPC,
then gets encapsulated in GTP by the EPC, and finally gets turned right
back around on a different VLAN and sent back out the exact same port
on its way to the ENB.
So not only does the traffic cross that particular ethernet port twice
on the EPC, but assuming that you have your EPC plugged directly into a
router as we do, the same traffic from the internet to your users will
traverse your PDN router on at least three ports: once coming from the
internet, twice going-and-coming to/from the EPC, and then once more on
its way out to an ENB. This traffic flow wouldn't look any different
regardless of whether you are trying to route between EPC and ENBs or
bridge/switch.
In your (Tristan's) case, I am a little confused by your description.
If I understand you correctly, you have a switch physically located
close to the WIB that you have the EPC plugged into, then a Mimosa path
to a site somewhere where you have another router and (presumably) one
or more ENBs, and you have the gateway addresses for the management and
bearer VLANs sitting not on your WIB but on the router that sits at the
other end of the Mimosa path. Do I have that correct?
If that's right, you presumably have the WIB and the close end of the
Mimosa path plugged into the same switch with the EPC, and then have
the VLANs trunked like this:
WIB port on switch: PDN VLAN tagged
EPC port on switch: PDN, Mgmt, and Bearer VLANs tagged
Mimosa port on switch: Mgmt and Bearer VLANs tagged
With that arrangement, presuming that at the remote site the ENB is
also being trunked the management and bearer VLANs directly, it matters
not one whit which router on your network you put the .1 (or whatever)
addresses on for the management and bearer subnets. In fact, you could
get away with not putting those addresses on any router, and not even
bothering to set the next-ip-gateway for the 'bearer' and
'external-management' network configs on either the EPC or ENB. It
would all still work since the EPC and ENBs are all talking to each
other over the same ethernet broadcast domain.
This isn't an entirely bad set-up, either, because the WIB never sees
anything but the PDN traffic, and the only device that encounters the
traffic hairpinning is the switch that the EPC is plugged into. But
since it's a switch (and presumably a modern-enough one), it is
non-blocking / has enough backplane capacity for all ports to be moving
their rated speed in each direction simultaneously. So, who cares.
Now, if I've misunderstood and you actually both want and are working
to achieve a routed set-up, and the bearer interfaces of each ENB will
be in their own subnet(s) apart from the bearer subnet on the EPC, then
where the gateway address sits for the EPC's bearer subnet will of
course matter and have an effect on the flow of traffic between it and
the ENBs.
-- Nathan
From:[email protected] [mailto:[email protected]] On
Behalf Of Jeremy Austin
Sent: Tuesday, January 31, 2017 3:40 PM
To: Tristan Johnson; [email protected]
Subject: Re: [Telrad] Setting up EPC
Tristan, this fits into the discussion Nathan and I were having -- I'm
currently using the single port method, and he is not.
From what I can tell, Bearer traffic will use the bearer gateway, and
management traffic will use the management gateway.
I do not believe that there is any doubling back, so to speak. There
are some firewall rules that Nathan can describe in greater detail,
much of which you can find in the list archives.
I have been finding radically different iperf behavior when testing the
EPC's management interface directly on L2 vs. L3. I do not yet know
whether this dichotomy affects bearer traffic; if anyone can confirm
that would be awesome, as Telrad design docs appear to support both
setups.
I am possibly leaning toward Nathan's topology of porting all ENB
traffic back over VPLS, as I already have a full MPLS stack available.
On Tue, Jan 31, 2017 at 11:59 AM Tristan Johnson
<[email protected]> wrote:
Hey guys,
Working on getting our Telrad test gear going after, um, a couple
years now. (long waits and contract failures at some tower sites
perfect for LTE).
I've been working on getting the EPC working, and we do have our EPC
and EnB set up and functional. But, I'm curious if I have this
configured in the most effective and efficient way.. I'll be perfectly
honest, I'm not a switch guru, or VLAN man. I've routed from day one,
and never really used VLANs (strange as it may be). So we have an OSPF
routed network, and I'm trying to put the EPC at our head end. It goes
something like this.
(AZOTEL WIB router w/PDN vlan and another subnet for BH traffic from
the rest of our network) ---> Switch --> Mimosa radio pair -->Another
router with BH taffic IP, VLAN for EPC bearer, and VLAN for EPC
managment, with default route to Azotel WIB. EPC is plugged in to
switch with bearer and management pointing to far router, and PDN VLAN
pointing to WIB.
If you can follow that, my question revolves around how the EPC uses
ONE port to move all of it's traffic around, and if our traffic is
actually going to where it's supposed to without having to double
back. Say bearer traffic going to the WIB then to the EPC because of
the default route at that far router.
Or should all EPC VLANs terminate at the WIB?
I ask mainly because we have seen some inconsistent speed tests, and
when I do a traceroute to the EPC from that far router I get a failed
hop in between the router and the EPC in the list of 3 hops (which I
wouldn't expect to be 3 anyway). There is just some strangeness.
Thanks,
Tristan Johnson
Owner
www.wirelessdatanet.net <http://wirelessdatanet.net>
309-893-4152
--------------------------------------------------------------------------------
<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>
This email has been checked for viruses by Avast antivirus software.
www.avast.com
<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>
_______________________________________________
Telrad mailing list
[email protected]
http://lists.wispa.org/mailman/listinfo/telrad
_______________________________________________
Telrad mailing list
[email protected]
http://lists.wispa.org/mailman/listinfo/telrad
