On 30 October 2015 at 12:35, Jesper Skriver <[email protected]> wrote:
Hey Jesper, > That would not be practical to implement for a router, implementations > typically have the L2 header cached and the L3 forwarding > constructs just point to a rewrite object that contain the > appropriate L2 encap for the next-hop selected by L3. > > What you are proposing means that a single L3 object needs to > point to different L2 rewrite objects depending on what L2 encap > was on the packet when received. Many architectures just cannot > do that, and for others it would for sure come at a performance > penalty. I'm surprised by this. Because LSR today could have single interface, which egresses native IPv4, IPv6, ARP, or MPLS, depending on ingress. And I know 7600 offers ethertype in egress rewrite information, so it could impose any ethertype as lookup result. Obviously high-touch platforms like ASR9k, MX, 7750SR, CX600/NE40 could also do any type of egress ethertype. In the proposed scenario, LSR would not change the ethertype, if it came in as MPLS-IP, it would go out as MPLS-IP, ingress LER would decide ethertype. I'm not surprised that there would be some platforms where this limitation exists, but I would have guessed those are very restricted L3 switches which already have many limitations, such as not supporting control-word etc. -- ++ytti _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
