12/9/ Zebra on the MSR 12/9/2015

2 What is Zebra? Free routing software distributed under GNU Modular design –process for each routing protocol, –zebra daemon for accessing kernel routing table Supports various protocols: –BGP4 –RIPv1, RIPv2, RIPng –OSPFv2, OSPFv3 IPv6 and SNMP support Platforms –GNU/Linux 2.4.X –FreeBSD 2.2.8, 3.1, 4.X, –NetBSD 1.4.X, OpenBSD 2.4 –Solaris 7

12/9/ Zebra on Linux/NetBSD Zebra BGPRIPOSPF Interface Table Routing Table Kernel Routing Protocols RIB Initial kernel/static routes and zebra updates through route socket, ioctl, netlink or /proc Interface type, addresses, status, MTU IFlist INTERFACE_UP INTERFACE_DOWN IPV4_ROUTE_ADD IPV4_ROUTE_DELETE REDISTRIBUTE_ADD REDISTRIBUTE_DELETE IPV4_NEXTHOP_LOOKUP Zebra generates a common routing information base (RIB) from various routing protocols, distributes routes between protocols and updates the kernel routing table with the routes it learnt. It also keeps track of the interface state and if an interface goes up/down, zebra notifies each routing protocol.

12/9/ Zebra on MSR Zebra BGPRIPOSPF Routing Table CP Kernel Routing Protocols RIBIFlist Resource Manager ConfigSignaling Routing Table Agent Virtual Interfaces SPC0SPC1SPC2SPC3SPC4SPC7 … User Space CP Kernel CP Processing Elements … Install route in FIPL On the MSR, Zebra should communicate with the Routing Table Agent (which is part of the CP) instead of directly with the kernel routing table. The Routing Table Agent then installs these routes in FIPL’s table on the SPC.

12/9/ API used to communicate with Route Table Need to implement following functions: –Add/delete route: kernel_add_ipv4(struct prefix *, struct rib *); kernel_delete_ipv4(struct prefix *, struct rib *); kernel_add_route(struct prefix_ipv4 *, struct in_addr *); –Add/delete interface address: kernel_address_add_ipv4(struct interface *, struct connected *); kernel_address_delete_ipv4(struct interface *, struct connected *); e.g., “ /16” nexthop interface The add/delete interface address functionality might not be needed for the MSR since addresses can be configured at MSR startup.

12/9/ Zebra  Route Table Agent Protocol Zebra BGPRIPOSPF Routing Protocols RIBIFlist Resource Manager ConfigSignaling Routing Table Agent User Space CP … struct routemsg { u_char msgtype; /* Add or delete route */ u_char prefixlen; struct in_addr prefix; struct in_addr nexthop; /* interface addr */ }; Zebra also needs to know static routes (such as default routes). At startup, the resource manager sends zebra all configured static routes. Then zebra is ready and can learn other routes from various routing protocols. nexthop can be either an interface index or interface address.