Operate and maintain
Documents under this category provide functional descriptions and procedures for configuring, operating, and maintaining 7705 SAR Gen 2 routers.
- Basic System Configuration Guide
  This guide describes file system management, boot option file (BOF) configuration, basic system management configuration, node timing, and synchronization functions.
- Interface Configuration Guide
  This guide describes how to provision Input/Output Modules (IOMs), Media Dependent Adapters (MDAs), connectors, and ports.
- Layer 2 Services and EVPN Guide
  This guide describes Layer 2 service and Ethernet Virtual Private Network (EVPN) functionality and provides examples to configure and implement Virtual Leased Lines (VLLs), Virtual Private LAN Service (VPLS), and EVPN.
- Layer 3 Services Guide: IES and VPRN
  This guide describes Layer 3 service functionality and provides examples to configure and implement Internet Enhanced Services (IES) and Virtual Private Routed Network (VPRN) services.
- MD-CLI User Guide
  This guide provides information about how to use the MD-CLI.
- MPLS Guide
  This guide provides an overview of Multiprotocol Label Switching (MPLS), Resource Reservation Protocol (RSVP), and Label Distribution Protocol (LDP) and provides configuration examples.
- MS-ISA and ESA Guide
  This guide provides an overview of services provided by integrated service adapters and extended service appliances, such as IPsec and Network Address Translation (NAT), and provides configuration examples.
- Multicast Routing Protocols Guide
  This guide provides an overview of multicast routing concepts and provides configuration examples for Internet Group Management Protocol (IGMP), Multicast Listener Discovery (MLD), and Protocol Independent Multicast (PIM).
- Quality of Service Guide
  This guide provides an overview of Quality of Service (QoS) policy management and provides configuration examples.
- Router Configuration Guide
  This guide dscribes logical IP routing interfaces and associated attributes such as IP addresses, as well as IP and MAC-based filtering, Virtual Router Redundancy Protocol (VRRP), and cflowd.
- Segment Routing and PCE User Guide
  This guide provides an overview of segment routing features with MPLS (SR-MPLS) data path encapsulations and path computation element (PCE) features.
- Services Overview Guide
  This guide provides a general overview of functionality provided by the routers and describes how to configure service parameters such as Service Access Points (SAPs), Service Distribution Points (SDPs), customer information, and user services.
- System Management Guide
  This guide describes system security features, SNMP and NETCONF features, and event and accounting logs; the guide also covers basic tasks such as configuring management access filters, passwords, and user profiles.
- Unicast Routing Protocols Guide
  This guide provides an overview of unicast routing concepts and provides configuration examples for Routing Information Protocol (RIP), Open Shortest Path First (OSPF), Intermediate-system-to-intermediate-system (IS-IS), and Border Gateway Protocol (BGP) routing protocols; also provides an overview of route policies and configuration examples.

DHCP persistence

The DHCP persistence feature on the 7705 SAR Gen 2 retains information learned through DHCP snooping across reboots. This information can include data such as the IP address, MAC binding information, lease length information, and ingress SAP information (required for VPLS snooping to identify the ingress interface). This information is referred to as the DHCP lease-state information.

When a DHCP message is snooped, the system performs the following steps to make the data persistent. For systems with only one CPM, only step 1 applies; for those with dual CPMs, all steps apply.

When a DHCP ACK is received from a DHCP server, the entry information is written to the active CPM compact flash. If writing is successful, the ACK is forwarded to the DHCP client. If persistency fails completely (for example, because of a bad compact flash), a trap is generated indicating that persistency can no longer be guaranteed.

If the complete persistency system fails, the DHCP ACKs are still forwarded to the DHCP clients. DHCP ACKs may get dropped and not forwarded to the DHCP clients only during small persistency interruptions, or in overload conditions of the compact flash.
DHCP message information is sent to the standby CPM, where the DHCP information is also logged on the compact flash. If persistency fails on the standby CPM, a trap is generated.

July 9, 2026