1. Base Protocol Spec Radia Perlman Radia.Perlman@sun.com

2. A few minor things to do Fold in draft of Bryant, et al, about using 4-byte, MPLS-like shim header, and distributed algorithm for choosing 19-bit nickname for RBridges Specify encoding of IS-IS packets: 3 cases: 1.Layer 3 IS-IS 2.RBridge IS-IS for core instance 3.RBridge IS-IS per-VLAN instance

3. Encapsulation Header S=Xmitting Rbridge D=Rcving Rbridge pt=“transit” hop count RBridge in/out Multicast flag original pkt (including L2 hdr) Shim hdr (MPLS format, 32 bits) label: 19 bit RBridge nickname/flag priority (3 bits); bottom of stack flg TTL (8 bits)

4. Shim header Label is either ingress or egress RBridge, depending on the flag –Multicast and unknown destination; ingress –Unicast; egress –19-bit nickname, chosen by distributed algorithm Priority and “bottom of stack” probably not useful for RBridges

5. Question 1: Should we make those “reserved” field? Maybe we’d use priority. I can’t imagine using “bottom of stack” for RBridges

6. Three types of IS-IS packets Regular router layer 3 IS-IS –Just like normal data traffic for RBridges –In theory we could optimize delivery only to links with IS-IS routers –And we could do the same for OSPF, BGP, RIP, … –WG decided not to bother optimizing, and to deliver to all campus links

7. RBridge IS-IS types Core instance (for RBridge-RBridge connectivity, and VLANs) Per-VLAN –Endnodes –Multicast receivers for IGMP-joined groups Decision: Use different multicast addresses in outer header to differentiate these instances

8. New Layer 2 Multicast addresses needed Address 1: For ordinary encapsulated data packets that will be flooded (multicast, unknown destination) Address 2: For core IS-IS RBridge instance Address 3: For per-VLAN IS-IS RBridge instance

9. Core Instance Dest = new multicast #2 Source=transmitting RBridge PT=RBridge-encapsulated outer hdr Multicast flag Ingress RBridge shim IS-IS packet, no layer 2 hdr inside

10. Per VLAN Instance Dest = new multicast #3 Source=transmitting RBridge PT=RBridge-encapsulated outer hdr Multicast flag Ingress RBridge shim IS-IS packet, no layer 2 hdr inside VLAN tag (12 bits + 4 reserved)

11. Question 2 So…is this all OK?

12. Conclusions Remember Algorhyme? For Usenix, I asked my son to write Algorhyme 2

13. Algorhyme v2 I hope that we shall one day see A graph more lovely than a tree. A graph to boost efficiency While still configuration-free. A network where RBridges can Route packets to their target LAN. The paths they find, to our elation, Are least cost paths to destination. With packet hop counts we now see, The network need not be loop-free. RBridges work transparently. Without a common spanning tree. Ray Perlner