Network Routing Guide

03 /Contents

• 01VRRP and VSRP: First-Hop Redundancy ExplainedGuide

  VRRP lets two or more routers share one gateway address so hosts keep a working default route when a router dies. Foundry extended it as VRRP-E and built VSRP to protect Layer 2 uplinks the same way.

• 02MPLS VPN: Labels, LSPs, Layer 3 and Layer 2 VPNsGuide

  MPLS forwards packets on short labels instead of IP lookups, and MPLS VPNs use those labels to carry many customers over one provider core while keeping their routing tables apart.

• 03IPv6 Transition: Dual Stack, Tunnels, Translation and PlanningGuide

  IPv4 exhaustion is complete; the transition to IPv6 is a set of coexistence mechanisms, not a switch to flip. Dual stack where you can, translate where you must, and plan addresses before touching a router.

• 04Core Router: Role, Architecture and Design RulesGuide

  A core router moves packets between aggregation points at line rate and does almost nothing else. Everything about its design, from chassis to redundant control modules, follows from that single job.

03.1 /Orientation

Routing is the part of the network that hosts never see and always depend on. A router forwards packets by destination prefix using a table built from static entries and routing protocols; a redundancy protocol lets two routers share one gateway address so that hosts survive a failure; MPLS wraps packets in labels so a provider can carry many customers' private networks over one core; and IPv6 changes the address plan underneath all of it. The four guides in this section cover those mechanisms in the order an enterprise usually meets them.

VRRP and VSRP explains virtual router election, priority and preemption, the virtual MAC, and Foundry's two extensions: VRRP-E for load-sharing gateways and VSRP, a proprietary Layer 2/3 redundancy protocol that offered sub-second failover as an alternative to spanning tree. MPLS VPN covers labels and LSPs, VRFs, route distinguishers and targets, MP-BGP and the PE/P/CE roles, drawn from the NetIron service-provider material. IPv6 transition is the dual-stack, tunnelling and translation toolkit with an address plan and a deployment checklist, and Core router separates control plane from forwarding plane and explains why a chassis in the core is built the way it is.

Foundry's routers were the NetIron family: the NetIron 400 and 800 Internet core routers around the turn of the century, the IMR 640 for MPLS services, and the XMR and MLX platforms that outlived the company under Brocade and later Extreme Networks. The NetIron profile in the archive covers that hardware; the guides here cover what the hardware did. Routing-capable BigIron and FastIron images also appear where a Layer 3 switch is the practical gateway.

The old site's search engine logged one query more than any other, and enough people linked to the results page for it to survive in the backlink record: ipv6. That URL now resolves to the IPv6 transition guide, which is the honest modern answer to the question those engineers were asking in the mid-2000s. The other recovered documents are the VRRP chapter of the enterprise configuration guide, the VSRP whitepaper, the BGP/MPLS VPN chapter of the IMR 640 service provider guide, the MPLS static LSP command reference and the data centre core solution page.

Each guide ends with verification commands and a short list of the mistakes that cause outages: preemption on a router with slow boot, a missing route target, an untested IPv6 firewall policy, a core with a single management module. The section is deliberately shorter than switching; the wave-two backlog adds OSPF and BGP basics once the first pages have indexed.