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L2VPN Interworking - standards based?

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Nov 25th, 2013
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Hi Guys,


Just reading through RFC6575 - ARP Mediation for IP Interworking for L2VPNs, and noticed that the Cisco implementation doesn't seem to be as mentioned in the RFC.


The CE (CE1) router with Ethernet L2 Attachment Circuit when performs ARP for remote CE IPv4 address, the local PE router responds with its own MAC Address. And that's where IOS stops following the RFC.


As per the RFC, the local PE router when learns about the local CE IP address, advertises that to remote PE router in IP Address List TLV in LDP Label Mapping message. I dont see any Label Mapping messages.


Also, the PE router learns the IPv4 address of CE (CE2) router connected via a PPP L2 Attachment Circuit when the CE router sends a CONFREQ message to PE with its IP address. This PE router then advertises that to remote PE router in IP Address List TLV in LDP Label Mapping message. I dont see that either.


Question is - do the PE routers just forward everything to remote PE after removing the L2 header?


Amit.

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Alessio Andreoli Wed, 11/27/2013 - 12:53
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Hi Amit, could you point which section of that RFC is unfamiliar with Cisco procedures? The section 3.0 of the same RFC states:    3.  IP Layer 2 Interworking Circuit     The IP Layer 2 Interworking Circuit refers to interconnection of the    Attachment Circuit with the IP Layer 2 Transport pseudowire that    carries IP datagrams as the payload.  The ingress PE removes the data    link header of its local Attachment Circuit and transmits the payload    (an IP packet) over the pseudowire with or without the optional    control word.  If the IP packet arrives at the ingress PE with    multiple data link headers (for example, in the case of bridged    Ethernet PDU on an ATM Attachment Circuit), all data link headers    MUST be removed from the IP packet before transmission over the    pseudowire (PW).  The egress PE encapsulates the IP packet with the    data link header used on its local Attachment Circuit.     The encapsulation for the IP Layer 2 Transport pseudowire is    described in [RFC4447].  The "IP Layer 2 Interworking Circuit"    pseudowire is also referred to as "IP pseudowire" in this document.     In the case of an IPv6 L2 Interworking Circuit, the egress PE MAY    modify the contents of Neighbor Discovery or Inverse Neighbor    Discovery packets before encapsulating the IP packet with the data    link header.   This seems perfectly aligned with what Cisco Systems implements. This RFC was written by Cisco through Eric Rosen, so that would be really cool if Cisco did not implement this yet! :)  Hope to read you soon Alessio

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