Olivier
2017-Jan-24 08:36 UTC
[asterisk-users] Understanding how LLDP works with DHCP [SOLVED]
2017-01-19 18:19 GMT+01:00 Jose Flores Galicia <flojose at gmail.com>:> 2017-01-19 4:09 GMT-06:00 Olivier <oza.4h07 at gmail.com>: > >> Hello, >> >> For years, I used to configure SIP phone VLAN membership through a DHCP >> server. >> >> Here are the details: >> - I dedicate a LAN port on a switch to voice VLAN >> - somewhere else, I configure a DHCP server to serve LAN addresses within >> voice VLAN >> - any other switch port connected to an other DHCP server is explicitely >> excluded from voice VLAN >> - new SIP hardphones are first connected to the dedicated voice VLAN >> port: after several reboots, they get an address within voice VLAN address >> range and save VLAN tag somewhere within their persistent memory >> - SIP phones are then moved to an other switch port: as they boots, they >> request a LAN address using previously received VLAN tag. >> >> Now I would like to improve this process using LLDP. >> I ran a couple of tests in my lab and still have some questions: >> >> >> 1. My lab switch sends within LLDP frames, a list of VLANs. One is named >> "default" and the other is named "voice". >> Do LLDP-capable phones look for a specific name to elect the VLAN tag >> they will later use to build DHCPDISCOVER request or do they look for >> something else (medPolicy) ? >> >> 2. With LLDP, do you still need your DHCP server to embed VLAN membership >> data within DHCPOFFER or is it a thing of the past ? >> >> 3. Have you been successfull with LLDP on a KVM guest networked to an >> LLDP-enabled switch through a linux bridge (see [1]) ? >> Where can I find information regarding the line bellow: >> echo 16384 > /sys/class/net/<bridge_name>/bridge/group_fwd_mask >> >> >> [1] https://thenetworkway.wordpress.com/2016/01/04/lldp-traffic- >> and-linux-bridges/ >> >> >> Best regards >> >> >> -- >> _____________________________________________________________________ >> -- Bandwidth and Colocation Provided by http://www.api-digital.com -- >> >> Check out the new Asterisk community forum at: >> https://community.asterisk.org/ >> >> New to Asterisk? Start here: >> https://wiki.asterisk.org/wiki/display/AST/Getting+Started >> >> asterisk-users mailing list >> To UNSUBSCRIBE or update options visit: >> http://lists.digium.com/mailman/listinfo/asterisk-users >> > > Hi Oliver. > > 1. Actually there are 2 protocols which must be supported on switch and ip > phone, one is LLDP wich inventories both ways. IP Phone <-> Switch, to > ellaborate on both devices MIB database with switching/routing/app > capabilities of their partner; second is the LLDP-MED (Media Endpoint > Discovery) which is capable of sending L2/L3 settings to devices. These > settings are in several categories, concerning your question is "Network > Policy" settings wich will be sent to the ip phone based on their app > capabilities (LLDP). > "Network Policy" settings can contain VLAN ID for voice and other ID for > Data, and other for Video, etc. Once the LLDP-MED "Network Policy" settings > are received on ip phone, will tag the phone traffic on the specified VLAN, > On switching capable ip phones (2 or more ethernet interfaces), probably > will only tag phone traffic, and leave the switched traffic on the access > vlan. > So ip phone sends DHCPREQUEST on the VLAN ID set by LLDP-MED. > > 2. DHCP VLAN settings will probably being ignored since most of devices > will prefer LLDP-MED settings. > > 3. With LLDP enabled on KVM guest, you can obtain information about > network devices attached, their capabilities, brand, model, etc. I have > never tried but LLDP-MED supposed only to work on next switch device (Link > Layer), not a propagation protocol. > > > I always have deployed LLDP-MED capable ip phones on a LLDP-MED capable > network is: > 1.- Enable LLDP on all access switches so they can advertise and receive > LLDP information. > 2.- Configure LLDP-MED on all ports where will be connected ip phones and > set the correct Network Policy, sending LLDP-MED capable voice devices to > voice VLAN ID > 3.- DHCP server exists attached to voice VLAN ID, as LLDP-MED will provide > same VLAN ID, phone will receive at the first boot their DHCP settings. > > Best Regards. > > > > -- > _____________________________________________________________________ > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > > Check out the new Asterisk community forum at: https://community.asterisk. > org/ > > New to Asterisk? Start here: > https://wiki.asterisk.org/wiki/display/AST/Getting+Started > > asterisk-users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >Hello, Combining a Yealink phone with a Ubiquiti switch, and thanks to above explanation,I could at last have my very first working LLDP experiment ! To sum up things: it seems an LLDP-enabled switch port would send a frame including an LLDP policy. This LLDP policy (which can be specific to each port) describe which tag to use to "enter" Voice VLAN. In turn LLDP-enabled phone would tag its DHCP DISCOVER request with appropriate VLAN tag value and there is no need to include vendor-specific VLAN data in DHCP OFFER anymore. The benefit is that with LLDP, any factory-reset phone can be plugged in any LLDP-enabled network and get appropriate VLAN config. Thanks for helping. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.digium.com/pipermail/asterisk-users/attachments/20170124/b366782f/attachment.html>