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Messages - netspork

#1
I have another few links to play with, but honestly, I'm probably just going to go with static neighbor definitions going forward.

I mean, I pretty much have two types of links that I need to run OSPF over, and I don't really trust either:

- Some flavor of metro-ethernet delivered over PON, which means I'm on a network that's primarily for small/medium businesses and probably has only a handful of customers running any kind of non-DIA traffic.  And the last hop in that setup is some little GPON ONT that is basically disposable hardware.  I would not bet any sort of money on what the ONT or the OLT boxes do to multicast traffic.  I would not bet any sort of money that those managing that network care about this.

- Links over wireless gear built for the WISP industry.  Sure, it's supposed to be a transparent bridge, but again, do I trust Ubiquiti has multicast handled right in their very-modified fork of DD-WRT?  Do I dare inquire as to what the "multicast enhancement" checkbox on the "Network" tab of the config does?  On the IgniteNet MetroLinq 60GHz gear, do I trust that their fork of DD-WRT is doing sane things with multicast?  I mean, it's nice gear and where else can I get links between buildings at more than 1Gb/s for just over $1K for both ends?  But are they doing the "right thing" when they tie the wireless interface(s) (there's a 5GHz backup radio) and the ethernet interface into a bridge interface WRT multicast?

I'm just not sure I want to go down either rabbit hole.  Somewhere on my bookshelf I actually have some old Cisco Press book on OSPF, I had a decent understanding of it, but that was when I was running it over frame relay and ATM links and I was full-time with an ISP and spent at least 50% of my day on the network side of things.  This nonsense of troubleshooting OSPF over transports with unknown properties sounds like as much fun as chasing down modem drops in the dialup days.
#2
Quote from: SimonV on March 07, 2018, 02:05:53 AM
I would switch to point-to-point, which will disable DR/BDR elections, and define manual neighbour statements. This will switch from multicast to unicast.

Awesome.  That kind of did it, but "point-to-point" did not allow static neighbors to be set.  For that I had to change to "non-broadcast".  I'm now pairing that with the manual/static neighbor declarations and that has fixed one site.  I'll be trying the same on a wonky wireless link that is supposed to be a transparent bridge, but likely isn't.

This is a chart I found that was helpful:

#3
And... that was incorrect.  Just different default timers on these different network types, so it took longer to flap.
#4
Holy shit, two birds with one stone.

Resolved both with the "point-to-multipoint" type.

Anyone feel like commenting on why that's the fix?  Or what's different between Sidera (now "Crown Castle", which is an idiotic name) and Pilot's GPON service that would "break" OSPF when set to the default type (broadcast I guess)?
#5
I could really use a guide to all of them:

265-canal-switch(config-if)#ip ospf network ?
  broadcast            Specify OSPF broadcast multi-access network
  non-broadcast        Specify OSPF NBMA network
  point-to-multipoint  Specify OSPF point-to-multipoint network
  point-to-point       Specify OSPF point-to-point network


Not so much when it's a normal network, but when there's something in between that might alter or block traffic required for OSPF to work.

At this site, the underlying "metro-e" network is GPON-based and there's an ONT that's probably disposable/generic crap.  Who knows what it does when it sees multicast.  In other areas I have wireless bridges.  These too can do weird things to multicast because "transparent" seems to be a fluid definition.  I say this after adding an IgniteNet MetroLinq 60GHz bridge where I have a different problem and the switch is being helpful and telling me the dead timer is expiring.  Why?  Who knows.

Of all these ospf network types, what are each useful for in some non-enterprise settings like this?  I mean, I have both problematic sites all wired up with statics, so I can test.  I guess I'll just cycle through all four and see if any stop the flapping... :)
#6
Hi all, this should be very simple - we have an old 3550 at a site served by a metro ethernet provider and a very simple ospf config (see below - just redistributing connected/statics).  Never had any issues.  Today we flipped over to a new metro-e provider. Both providers terminate in the same core router and again, same config (literally copy/pasted from one subinterface to another).  OSPF came up, but now seems to die every minute:

Mar  6 02:28:18.325 EST: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.1 on Vlan49 from LOADING to FULL, Loading Done
Mar  6 02:29:15.525 EST: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.1 on Vlan49 from LOADING to FULL, Loading Done
Mar  6 02:30:03.379 EST: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.1 on Vlan49 from LOADING to FULL, Loading Done
Mar  6 02:30:59.863 EST: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.1 on Vlan49 from LOADING to FULL, Loading Done


Soooo... checked with the provider, they swear they aren't doing anything that would muck around with multicast, etc.

I'm running through the debug output a bit, but frankly I don't know what I'm looking for - there's no big ERROR! ERROR!, I see the options flags matching in send/recv...  This little error is not really digging stuff up for me on google that's useful, just other people sending debug info but no one commenting on this in particular:

Cannot see ourself in hello from X.X.X.1 on Vlan49, state INIT

Debug from edge below, core after that:


Mar  6 02:26:26.011 EST: OSPF: Synchronized with X.X.X.1 on Vlan49, state FULL
Mar  6 02:26:26.011 EST: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.1 on Vlan49 from LOADING to FULL, Loading Done
Mar  6 02:26:26.495 EST: OSPF: Rcv LS UPD from X.X.X.1 on Vlan49 length 196 LSA count 1
Mar  6 02:26:28.511 EST: OSPF: Send with youngest Key 1
Mar  6 02:26:31.471 EST: OSPF: Rcv LS UPD from X.X.X.1 on Vlan49 length 196 LSA count 1
Mar  6 02:26:31.475 EST: OSPF: Send with youngest Key 1
Mar  6 02:26:31.763 EST: OSPF: Send with youngest Key 1
Mar  6 02:26:41.764 EST: OSPF: Send with youngest Key 1
Mar  6 02:26:51.764 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:01.765 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:11.765 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:12.465 EST: OSPF: Cannot see ourself in hello from X.X.X.1 on Vlan49, state INIT
Mar  6 02:27:12.465 EST: OSPF: Neighbor change Event on interface Vlan49
Mar  6 02:27:12.465 EST: OSPF: DR/BDR election on Vlan49
Mar  6 02:27:12.465 EST: OSPF: Elect BDR 0.0.0.0
Mar  6 02:27:12.465 EST: OSPF: Elect DR X.X.X.18
Mar  6 02:27:12.465 EST:        DR: X.X.X.18 (Id)   BDR: none
Mar  6 02:27:12.465 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:12.469 EST: OSPF: 2 Way Communication to X.X.X.1 on Vlan49, state 2WAY
Mar  6 02:27:12.469 EST: OSPF: Neighbor change Event on interface Vlan49
Mar  6 02:27:12.469 EST: OSPF: DR/BDR election on Vlan49
Mar  6 02:27:12.469 EST: OSPF: Elect BDR X.X.X.1
Mar  6 02:27:12.469 EST: OSPF: Elect DR X.X.X.18
Mar  6 02:27:12.469 EST:        DR: X.X.X.18 (Id)   BDR: X.X.X.1 (Id)
Mar  6 02:27:12.469 EST: OSPF: Send DBD to X.X.X.1 on Vlan49 seq 0xF48 opt 0x52 flag 0x7 len 32
Mar  6 02:27:12.469 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:12.469 EST: OSPF: Neighbor change Event on interface Vlan49
Mar  6 02:27:12.469 EST: OSPF: Elect BDR X.X.X.1
Mar  6 02:27:12.469 EST: OSPF: Elect DR X.X.X.18
Mar  6 02:27:12.469 EST:        DR: X.X.X.18 (Id)   BDR: X.X.X.1 (Id)
Mar  6 02:27:12.469 EST: OSPF: Neighbor change Event on interface Vlan49
Mar  6 02:27:12.469 EST: OSPF: DR/BDR election on Vlan49
Mar  6 02:27:12.469 EST: OSPF: Elect BDR X.X.X.1
Mar  6 02:27:12.469 EST: OSPF: Elect DR X.X.X.18
Mar  6 02:27:12.473 EST:        DR: X.X.X.18 (Id)   BDR: X.X.X.1 (Id)
Mar  6 02:27:12.473 EST: OSPF: Rcv DBD from X.X.X.1 on Vlan49 seq 0x18B6 opt 0x52 flag 0x7 len 32  mtu 1500 stat
e EXSTART
Mar  6 02:27:12.473 EST: OSPF: First DBD and we are not SLAVE
Mar  6 02:27:12.473 EST: OSPF: Rcv DBD from X.X.X.1 on Vlan49 seq 0xF48 opt 0x52 flag 0x2 len 1112  mtu 1500 sta
te EXSTART
Mar  6 02:27:12.473 EST: OSPF: NBR Negotiation Done. We are the MASTER
Mar  6 02:27:12.477 EST: OSPF: Send DBD to X.X.X.1 on Vlan49 seq 0xF49 opt 0x52 flag 0x3 len 1112
Mar  6 02:27:12.477 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:12.481 EST: OSPF: Rcv DBD from X.X.X.1 on Vlan49 seq 0xF49 opt 0x52 flag 0x0 len 32  mtu 1500 state
EXCHANGE
Mar  6 02:27:12.481 EST: OSPF: Send DBD to X.X.X.1 on Vlan49 seq 0xF4A opt 0x52 flag 0x1 len 32
Mar  6 02:27:12.481 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:12.481 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:12.481 EST: OSPF: Send LS REQ to X.X.X.1 length 12 LSA count 1
Mar  6 02:27:12.485 EST: OSPF: Rcv DBD from X.X.X.1 on Vlan49 seq 0xF4A opt 0x52 flag 0x0 len 32  mtu 1500 state
EXCHANGE
Mar  6 02:27:12.485 EST: OSPF: Exchange Done with X.X.X.1 on Vlan49
Mar  6 02:27:12.485 EST: OSPF: Rcv LS UPD from X.X.X.1 on Vlan49 length 196 LSA count 1
Mar  6 02:27:12.485 EST: OSPF: Synchronized with X.X.X.1 on Vlan49, state FULL
Mar  6 02:27:12.485 EST: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.1 on Vlan49 from LOADING to FULL, Loading Done
Mar  6 02:27:14.986 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:16.978 EST: OSPF: Rcv LS UPD from X.X.X.1 on Vlan49 length 196 LSA count 1
Mar  6 02:27:19.478 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:21.766 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:21.818 EST: OSPF: Rcv LS UPD from X.X.X.1 on Vlan49 length 196 LSA count 1
Mar  6 02:27:21.818 EST: OSPF: Send with youngest Key 1
Mar  6 02:27:31.766 EST: OSPF: Send with youngest Key 1


core:

Mar  6 02:25:38.271 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:25:48.012 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:25:57.473 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:06.921 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:16.798 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: X.X.X.18 address X.X.X.18 is dead
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: X.X.X.18 address X.X.X.18 is dead, state DOWN
Mar  6 02:26:18.269 EDT: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.18 on GigabitEthernet0/1/4.2391 from FULL to DOWN,
Neighbor Down: Dead timer expired
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Nbr X.X.X.18: Clean-up dbase exchange
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Neighbor change event
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: DR/BDR election
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect BDR X.X.X.1
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect DR X.X.X.1
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect BDR 0.0.0.0
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect DR X.X.X.1
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: DR: X.X.X.1 (Id)
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391:    BDR: none
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Reset flush timer
Mar  6 02:26:18.269 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Remember old DR X.X.X.18 (id)
Mar  6 02:26:25.990 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: 2 Way Communication to X.X.X.18, state 2WAY
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Neighbor change event
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: DR/BDR election
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect BDR 0.0.0.0
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect DR X.X.X.18
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect BDR X.X.X.1
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect DR X.X.X.18
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: DR: X.X.X.18 (Id)
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391:    BDR: X.X.X.1 (Id)
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Nbr X.X.X.18: Prepare dbase exchange
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send DBD to X.X.X.18 seq 0x1689 opt 0x52 flag 0x7 len 32
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Set flush timer
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Remember old DR X.X.X.1 (id)
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Neighbor change event
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: DR/BDR election
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect BDR X.X.X.1
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Elect DR X.X.X.18
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: DR: X.X.X.18 (Id)
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391:    BDR: X.X.X.1 (Id)
Mar  6 02:26:25.994 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:26.000 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Rcv DBD from X.X.X.18 seq 0x1C0A opt 0x52 flag 0x7 len 32  m
tu 1500 state EXSTART
Mar  6 02:26:26.000 EDT: OSPF-1 ADJ   Gi0/1/4.2391: NBR Negotiation Done. We are the SLAVE
Mar  6 02:26:26.000 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Nbr X.X.X.18: Summary list built, size 54
Mar  6 02:26:26.000 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send DBD to X.X.X.18 seq 0x1C0A opt 0x52 flag 0x2 len 1112
Mar  6 02:26:26.000 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:26.005 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Rcv DBD from X.X.X.18 seq 0x1C0B opt 0x52 flag 0x3 len 1112
mtu 1500 state EXCHANGE
Mar  6 02:26:26.005 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send DBD to X.X.X.18 seq 0x1C0B opt 0x52 flag 0x0 len 32
Mar  6 02:26:26.005 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:26.009 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Rcv DBD from X.X.X.18 seq 0x1C0C opt 0x52 flag 0x1 len 32  m
tu 1500 state EXCHANGE
Mar  6 02:26:26.009 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Exchange Done with X.X.X.18
Mar  6 02:26:26.009 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Synchronized with X.X.X.18, state FULL
Mar  6 02:26:26.009 EDT: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.18 on GigabitEthernet0/1/4.2391 from LOADING to FU
LL, Loading Done
Mar  6 02:26:26.009 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send DBD to X.X.X.18 seq 0x1C0C opt 0x52 flag 0x0 len 32
Mar  6 02:26:26.009 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:26.009 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Rcv LS REQ from X.X.X.18 length 36 LSA count 1
Mar  6 02:26:26.009 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1
Mar  6 02:26:26.495 EDT: OSPF-1 ADJ   Gi0/1/4.2391: Send with youngest Key 1


And this is really all there is to the ospf config...

The only difference on the core side is that there are more "no passive-interface" statements and more "network" statements.
router ospf 1
router-id X.X.X.18
log-adjacency-changes
area 0 authentication message-digest
redistribute static subnets
passive-interface default
no passive-interface Vlan49
network X.X.X.0 0.0.0.255 area 0
network X.X.X.Y 0.0.0.255 area 0
!
!
interface Vlan49
ip address X.X.X.18 255.255.255.252
ip ospf authentication message-digest
ip ospf message-digest-key 1 md5 7 secretzzzz
!
! core side interface (ASR-1002-X)
!
interface GigabitEthernet0/1/4.2391
encapsulation dot1Q 2391
ip address X.X.X.17 255.255.255.252
no ip redirects
no ip unreachables
no ip proxy-arp
ip ospf authentication message-digest
ip ospf message-digest-key 1 md5 7 secretzzzzzz


Stumped, any ideas?
#7
Routing and Switching / Re: Force VLAN up?
October 30, 2017, 01:40:42 PM
I just added another VLAN and I'm seeing this again.  VLAN interface created, added to a trunk port, VLAN is up/down.  In the 5 minutes or so it took me to write that, get distracted, and come back here, it flipped to up/up.  This is the first time I saw this happen without me fiddling around in the switch to try to get it to up/up.  So some kind of timer must hit (I'm guessing something spanning tree related).  Just another datapoint for anyone finding this thread.

#8
OK, so let's say we're cheap and we are going to bond two 1G ports (to be fair, the cards are affordable, tossing that ASR-1002X in the garbage is not).  LAGG is de-facto standard across all vendors?
#9
Routing and Switching / Carrier standards for sub-10GE?
October 17, 2017, 01:49:42 PM
Question - what's the current standard for bonding 1GE links when buying transit from a large carrier?  We have two upstreams, one is so flexible they'll just do anything, the other will drag this order out over months if we don't just call them and TELL them how we want to do it.  LAGG or something else?  I assume something vendor neutral?  One transit provider is running Brocade at L2/L3 the other is unknown L2, Cisco L3.

Long ago when trying to aggregate multiple FE connections we were pushed toward just letting BGP do this, but I think that's silly and probably wrong.
#10
Yo, Szechuan Rick - what are you saying, maybe they don't? :)

I can setup a test case without breaking anyone, I'll check it out.
#11
Fudge.  I was hoping I was just mistaken...

Is there any sort of "virtualization" hack?  Like a layer-2 VRF for VLANs?
#12
Bear with me - I do more sysadmin and web dev work these days.  My IOS heyday was like IOS 10 and 11.

So I'm probably missing an easy workaround to this problem.  I have an ASR-1002-X and multiple NNIs to some metro-ethernet providers. So far I've been able to specify VLANs when we order, so for example, provider 1, VLANs 100-200, provider 2, VLANs 201-300, etc. Now I have an NNI coming from another provider that does not allow me to specify the range of VLANs and they will overlap with the others.

From playing around with this, I see on the ASR that the VLANs are "global" to the router.  If I create a subint and vlan on one physical interface and then on another different physical interface, they see each other's traffic as if I've created a bridge.  I imagine there's a way to avoid that.  Pointers?
#13
Routing and Switching / Re: Force VLAN up?
August 11, 2017, 01:40:02 AM
Quote from: srg on August 11, 2017, 12:33:07 AM
There's no need for an access interface to be up, a trunk works as well. The initial configuration should work, given that the VLAN exists.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_52_se/configuration/guide/3560scg/swint.html#wp2040589
QuoteSVI Autostate Exclude
The line state of an SVI with multiple ports on a VLAN is in the up state when it meets these conditions:

•The VLAN exists and is active in the VLAN database on the switch.

•The VLAN interface exists and is not administratively down.

•At least one Layer 2 (access or trunk) port exists, has a link in the up state on this VLAN, and is in the spanning-tree forwarding state on the VLAN.

Pretty sure I have the last (port that's up, VLAN as an allowed member of the trunk), but was only able to get the VLAN up with a weird sequence of "shut/no shut" and "status active" commands.  Perhaps the STP part?  The other side of the trunk is a ubiquiti wireless AP in bridge mode, and one of the clients of that AP has a Netonix switch hanging off of it where these VLANs are all de-encapsulated and presented on various access ports on that switch.  This all works from end to end - just had this issue today when swapping the 3750 in for a 3550.

As requested, the use case here is to have this switch handle layer 3 stuff and have another switch that's only got layer 2 capabilities present these vlans untagged to various customers.

--- 3750 ---- trunk port ----  AP ---  wireless --- CPE --- trunk port ---- Netonix switch ---- customer per port

So vlan 101 ends up on a port of the netonix, vlan 102 on another port, etc.  The netonix has no layer 3 capabilities, so that's why I'm having the 3750 handle that...  Does that make sense?
#14
Routing and Switching / Re: Force VLAN up?
August 10, 2017, 09:14:31 PM
Should have mentioned, 3750 doesn't have the "autostate" command.
#15
Routing and Switching / Force VLAN up?
August 10, 2017, 07:26:42 PM
Hi all, this is a really common question, but I'm having trouble narrowing down an answer that addresses my use case.

I know the rule for a VLAN interface to come "up/up" is that there must be at least one access with that VLAN configured on it and that port must be up. The "autostate" stuff for VLANs will then mark the VLAN up.  Makes sense, I get it.

What about a scenario where the only place I need that VLAN is a trunk port?  In that case (at least on 3750 and similar), the port only comes up if you jiggle things around ("state active" in the vlan config, "shut/no shut" in the vlan interface config), and that's probably not going to survive a reload.

Shorthand example:

int gig 1/0/2
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 101,102
switchport mode trunk

int vlan 101
ip address 10.10.10.1 255.255.255.0


In that scenario, "vlan 101" will remain down/down, and that's how it's supposed to work.

In my use-case, I have no need to have vlan 101 on a port that's in access mode.  gig 1/0/2 above goes to a dumb layer 2 switch that puts vlan 101 on a few access ports. 

How can I make vlan 101 stay up/up no matter what?

I've seen some interesting/dumb hacks, like forcing a port up by disabling keepalives and then throwing the vlan over there, but that's just terrible and I won't do it.