Re: [L2tpext] Re: Local CE IP Address AVP
Mark Lewis <mark@mjlnet.com> Sat, 30 April 2005 14:54 UTC
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Date: Sat, 30 Apr 2005 15:53:00 +0100
From: Mark Lewis <mark@mjlnet.com>
Subject: Re: [L2tpext] Re: Local CE IP Address AVP
To: Carlos Pignataro <cpignata@cisco.com>
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Hi Carlos, > >IMHO, there are other specifics to the IP-L2 transport over L2TPv3 apart >from the `Local CE IP Address AVP'. Sure, the 'Local CE IP Address AVP' is obviously only designed for the ARP mediation component of IP-L2 transport. >For example, a PW Type for IP-L2 >Transport is not yet defined (in any draft and thus not allocated), I thought that IP L2 transport had been allocated the PW type 0x000B, hadn't it?? (http://www1.ietf.org/proceedings_new/04nov/IDs/draft-ietf-pwe3-iana-allocation-07.txt) Regards, Mark >RCs >(like mismatch ARP Med), should not use the value of `1 - Only non-IP >data packets require sequencing' for sequencing, etc. All these would >probably be too much for a document past last call, and only adding the >`Local CE IP Address AVP' would be incomplete. Besides, the AVP is >probably more related to or specific of IP-L2 transport than to the >signaling of l2vpns. > >We had actually been working in an `IP Layer 2 Transport over L2TPv3' >document including all of those considerations and numbers, which should >be ready very soon. > >Does that sounds reasonable? > >Best Regards, > >--Carlos. > >Circa 4/29/2005 11:24 PM, Ignacio Goyret said the following: >> This discussion should be continued in the WG list. >> >> Document by Mark Lewis attached inline at the end of this message. >> >> >> At 03:27 4/30/2005 +0100, Mark Lewis wrote: >> >>>Hi Wei, >>> >>>Further to my idea for a 'Local CE IP Address' AVP, please see >>>the attached word doc for a description. >>> >>>Any thoughts? >>> >>>Regards, >>> >>>Mark >>> >>> >>> >>>---- Original message ---- >>> >>>>Date: Fri, 29 Apr 2005 16:18:57 -0700 >>>>From: Wei Luo <luo@cisco.com> >>>>Subject: Re: draft-ietf-l2tpext-l2vpn-02.txt >>>>To: mark@mjlnet.com >>>> >>>>Hi Mark, >>>> >>>>Reply under yours. >>>> >>>>Mark Lewis wrote: >>>> >>>>>Hi Wei, >>>>> >>>>> >>>>> >>>>> >>>>>>>'The Interface Maximum Transmission Unit may be carried in >>>>>>>both the ICRQ and ICRP messages sent during L2TP session >>>>>>>(pseudowire) establishment between LACs. >>>>>> >>>>>>This text already exists in the current draft: >>>>>> >>>>>> The Interface MTU is a 2-octet value. This AVP MAY be >>> >>>present in >>> >>>>>> ICRQ and ICRP. >>>>>> >>>>> >>>>> >>>>>That'll teach me not to read a draft properly! >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>>>The Interface Maximum Transmission Unit AVP may also be >>>>>>>carried in a SLI message in order to signal reconfiguration of >>>>>>>the MTU of a local attachment circuit (after L2TP session >>>>>>>establishment). >>>>>> >>>>>>The reason it MTU AVP should not be put into a SLI message >>> >>>is because: >>> >>>>>> The MTU values of a given pseudowire, if advertised in both >>>>>> directions, MUST be identical. If they do not match, >>> >>>the pseudowire >>> >>>>>> SHOULD NOT be established. >>>>>> >>>>>>SLI messages do not estalish pseudowires but indicate >>> >>>status of the >>> >>>>>>pseudowires. >>>>>> >>>>> >>>>> >>>>> >>>>>Sure- I am aware that SLI are not used to establish >>> >>>pseudowires. What I was >>> >>>>>getting at was using an SLI to signal a **RE**configuration >>> >>>(modification) >>> >>>>>in the MTU of attachment circuit **AFTER** pseudowire >>> >>>establishment. >>> >>>>>So, for example: >>>>> >>>>>At PW establishment, LCCE.A sends an ICRQ to LCCE.B with an >>> >>>MTU AVP >>> >>>>>specifying an attachment circuit MTU of 1500. >>>>> >>>>>LCCE.B responds with an ICRP with an MTU AVP specifying an >>> >>>attachment >>> >>>>>circuit MTU of 1500. >>>>> >>>>>LCCE.A sends an ICCN and PW setup is complete. >>>>> >>>>> >>>>>***AFTER*** PW setup, an administrator then >>> >>>*modifies/reconfigures* the MTU >>> >>>>>on the attachment circuit on LCCE.A to 1600 (eg. using the >>> >>>'mtu 1600' >>> >>>>>command on Cisco boxes). >>>>> >>>>>Might an SLI be useful here to signal a **change** in >>> >>>attachment circuit >>> >>>>>MTU?? >>>> >>>>That could be one way to do it. The current draft writes >>> >>>that the >>> >>>>pseudowire should not be established whenever there is an MTU >>> >>>mismatch. >>> >>>> When a PE changes its own MTU, a mismatch occurs. >>> >>>Therefore, the PE >>> >>>>should first bring down the pseudowire and re-signal using >>> >>>the new MTU >>> >>>>value. >>>> >>>>The problem with SLI signaling is that if the peering PE is >>> >>>not ready to >>> >>>>change the MTU upon receiving the SLI, it probably sends a >>> >>>CDN to tear >>> >>>>down the pseudowire anyway. And both PEs have to go through >>> >>>the full >>> >>>>session signaling procedure to re-establish the pseudowire. >>> >>>So the >>> >>>>benefit of maintaining the pseudowire is quite small. >>>> >>>> >>>>> >>>>> >>>>> >>>>>>>Also, have you considered the addition of an 'Locally >>>>>>>Connected CE Device IP address' AVP to be used where ARP >>>>>>>mediation is carried out on the LCCE (IP mode L2VPN >>>>>>>interworking)? This might be useful to signal the IP address >>>>>>>of the connected local CE device to a remote LAC/LCCE. The AVP >>>>>>>would not be marked mandatory, and could be hidden (M,H bits). >>>>>>> >>>>>>>The AVP could potentially be carried in ICRQ and ICRP messages >>>>>>>if the local CE's IP address is known at the time of session >>>>>>>setup, or in an SLI if the CE's IP address becomes known (or >>>>>>>changes) after session setup has taken place. >>>>>>> >>>>>> >>>>>>That's certainly an interesting point. The ARP mediation >>> >>>draft defines >>> >>>>>>one LDP TLV for such a purpose, so I wonder if the authors >>> >>>prefer to >>> >>>>>>expanding that for L2TP in that draft or leaving it for >>> >>>this one. I >>> >>>>>>will ask. >>>>>> >>>>> >>>>> >>>>> >>>>> >>>>>As I am sure you are aware, the ARP mediation draft is >>> >>>currently going >>> >>>>>through IETF last call. I suggested the inclusion of the >>> >>>AVP I describe >>> >>>>>above, and received the following response: >>>>> >>>>> >>>>> >>>>>>5.0 CE IP Address Signaling between PEs >>>>>> >>>>>> >>>>>>******How about for L2TPv3? I must admit I can’t recall an >>>>>>L2TPv3 AVP that would allow the advertisement of the local >>>>>>CE’s IP address to the remote PE, but I may well be a little >>>>>>behind the times on this! I guess that if such an AVP exists >>>>>>(or will exist), it would have to be advertised either in the >>>>>>ICRQ/ICRP/ICCN or SLI (where discovery of the CE’s IP address >>>>>>did not coincide with pseudowire establishment)?? >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>>himanshu> We have not considered other PW signaling mechanisms >>>>>himanshu> in this draft. - may be future work item >>>>> >>>> >>>>The L2TP draft has already gone through last call. I will >>> >>>consult with >>> >>>>the WG chairs to see whether it can be added at this stage. >>>> >>>>Thanks again! >>>> >>>>---Wei >>>> >>>> >>>>> >>>>>Regards, >>>>> >>>>>Mark >> >> >> -------------------------------------------------------------- >> >> Local CE IP Address AVP >> >> >> The Local CE IP Address AVP (Attribute Type TBA) is used to signal >> the IP address of a locally attached CE device to a remote LCCE. >> >> The advertisement of the IP address of a CE device is relevant in >> a LAC-to-LAC pseudowire deployment, where IP (routed) mode L2VPN >> interworking is being used. In this case, a process referred to >> as 'ARP mediation' as described in [draft-ietf-l2vpn-arp-mediation-01.txt] >> may be performed in order to resolve addresses. >> >> The encoding of the Local CE IP Address AVP is as follows: >> >> 0 1 2 3 >> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 >> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >> |M|H|0|0|0|0| Length | 0 | >> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >> | TBA | Local CE IP Address >> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ >> | >> ++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++ >> >> >> The Local CE IP Address is a 4-octect field. It may contain either the >> IP address of a locally attached CE device, or a NULL value (0). >> >> The Local CE IP Address AVP MAY be present in ICRQ and ICRP messages if >> the local CE device’s IP address is known at the time of pseudowire setup. >> >> If the local CE device’s IP address becomes known (or changes) subsequent >> to pseudowire setup, then the local CE device’s IP address MAY be >> signalled to the remote LCCE by including a Local CE IP Address AVP in >> an SLI message. >> >> An SLI message containing a Local CE IP Address AVP with a NULL value (0) >> MAY also be used to signal the withdrawal of the IP address of the locally >> attached CE device. >> >> >> The Mandatory (M) bit of the Local CE IP Address AVP SHOULD be set to 0, >> and the Hidden (H) bit MAY be set to either 1 or 0. >> >> The Length of the Local CE IP Address AVP is 10 octets. >> >> >> _______________________________________________ >> L2tpext mailing list >> L2tpext@ietf.org >> https://www1.ietf.org/mailman/listinfo/l2tpext >> > >-- >--Carlos. >Escalation RTP - cisco Systems
_______________________________________________ L2tpext mailing list L2tpext@ietf.org https://www1.ietf.org/mailman/listinfo/l2tpext
- [L2tpext] Re: Local CE IP Address AVP Ignacio Goyret
- Re: [L2tpext] Re: Local CE IP Address AVP Carlos Pignataro
- Re: [L2tpext] Re: Local CE IP Address AVP Mark Lewis
- Re: [L2tpext] Re: Local CE IP Address AVP Carlos Pignataro
- Re: [L2tpext] Re: Local CE IP Address AVP Wei Luo
- RE: [L2tpext] Re: Local CE IP Address AVP Mark Lewis
- RE: [L2tpext] Re: Local CE IP Address AVP Sasha Vainshtein
- Re: [PWE3] RE: [L2tpext] Re: Local CE IP Address … Carlos Pignataro
- RE: [PWE3] RE: [L2tpext] Re: Local CE IP Address … Sasha Vainshtein
- Re: [PWE3] RE: [L2tpext] Re: Local CE IP Address … Carlos Pignataro
- RE: [PWE3] RE: [L2tpext] Re: Local CE IP Address … Sasha Vainshtein
- Re: [PWE3] RE: [L2tpext] Re: Local CE IP Address … Carlos Pignataro