What are the features and capabilities of the VPN Router 251?

The specifications of the VPN Router 251 are as follows:



IP routing and network addressing

  • RIPv1 and v2, ARP, ICMP
  • PPPoE (two sessions)
  • DHCP client and server: ‘static’ DHCP
  • Dynamic DNS and DNS proxy
  • NAT – many-to-many, many-to-one, one-to-one, port forwarding

VPN tunnelling

  • IPsec, including AH and ESP with main and aggressive mode IKE
  • PPTP
  • Nailed-up VPN tunnels with control PING
  • Support for branch VPN tunnels with NAT port forwarding
  • Up to five VPN tunnels


  • DES, 3DES
  • 3DES uses 3 independent keys; 168-bit key length (effective strength of 128 bits)
  • 128, 192 or 256-bit AES

Authentication services

  • 802.1x (via internal VPN Router 200 database or external RADIUS server)
  • X.509 digital certificates (PKCS #7 and #10; SCEP and CMP for open SSL Certificate Authorities)
  • Support for third-party Extensible Authentication Protocol (EAP) clients
  • Shared secret
  • Data authentication via SHA-1 or MD-5

VPN (Hard) Client support

  • On-demand or manual VPN tunnel establishment
  • Automatic IP fail-over assignment
  • Support for RADIUS authentication
  • Exclusive use mode

Stateful firewall

  • Stateful packet inspection of up to 50 rules
  • LAN to LAN, LAN to WAN, WAN to WAN
  • Denial of Service (DoS) protection
  • Attack logging and email alerts
  • ALGs for CU-SeeME, FTP, H.323, IPsec, RealAudio, VDoLive

Voice-friendly capabilities

  • SIP/H.323 ALGs for firewall and NAT traversal
  • Port-restricted Cone NAT for Nortel Unistim VoIP forwarding
  • Class-based queueing and bandwidth management for latency-sensitive VoIP traffic
  • Interoperable with Nortel Multimedia Communication Server, BCM and Communication Server VoIP portfolios


  • VPN Router Multi-Element Manager provides multi-device configuration for up to 2,500 VPN router devices, including the VPN Router 200 series
  • Web-based browser (HTTP) and/or Command-line interface (CLI) configuration
  • SNMP monitoring/alerts
  • Easy Install utility for centralized remote set-up
  • SSL/SSH administration
  • SFTP for software downloads
  • Denial of Service (DoS) attack alert and logging capability

Environmental compliance

  • FCC Class B
  • Underwriters Laboratory
  • CSA
  • FCC Part 68 (for xDSL devices)
  • CE

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