802.1Q Vlan; Vrrp; Hsrp - Cisco 6000 Series Configuration Manual

802.1Q VLAN

management interfaces. Flow control can be activated or deactivated for ingress traffic only. It is automatically
implemented for egress traffic.
802.1Q VLAN
A VLAN is a group of devices on one or more LANs that are configured so that they can communicate as if
they were attached to the same wire, when in fact they are located on a number of different LAN segments.
Because VLANs are based on logical instead of physical connections, it is very flexible for user and host
management, bandwidth allocation, and resource optimization.
The IEEE's 802.1Q protocol standard addresses the problem of breaking large networks into smaller parts so
broadcast and multicast traffic does not consume more bandwidth than necessary. The standard also helps
provide a higher level of security between segments of internal networks.
The 802.1Q specification establishes a standard method for inserting VLAN membership information into
Ethernet frames.

VRRP

The Virtual Router Redundancy Protocol (VRRP) eliminates the single point of failure inherent in the static
default routed environment. VRRP specifies an election protocol that dynamically assigns responsibility for
a virtual router to one of the VPN concentrators on a LAN. The VRRP VPN concentrator controlling the IP
addresses associated with a virtual router is called the master, and forwards packets sent to those IP addresses.
When the master becomes unavailable, a backup VPN concentrator takes the place of the master.
For more information on VRRP, see the Implementing VRRP module of IP Addresses and Services
Configuration Guide .

HSRP

Hot Standby Routing Protocol (HSRP) is a proprietary protocol from Cisco. HSRP is a routing protocol that
provides backup to a router in the event of failure. Several routers are connected to the same segment of an
Ethernet, FDDI, or token-ring network and work together to present the appearance of a single virtual router
on the LAN. The routers share the same IP and MAC addresses and therefore, in the event of failure of one
router, the hosts on the LAN are able to continue forwarding packets to a consistent IP and MAC address.
The transfer of routing responsibilities from one device to another is transparent to the user.
HSRP is designed to support non disruptive switchover of IP traffic in certain circumstances and to allow
hosts to appear to use a single router and to maintain connectivity even if the actual first hop router they are
using fails. In other words, HSRP protects against the failure of the first hop router when the source host
cannot learn the IP address of the first hop router dynamically. Multiple routers participate in HSRP and in
concert create the illusion of a single virtual router. HSRP ensures that one and only one of the routers is
forwarding packets on behalf of the virtual router. End hosts forward their packets to the virtual router.
The router forwarding packets is known as the active router . A standby router is selected to replace the active
router should it fail. HSRP provides a mechanism for determining active and standby routers, using the IP
addresses on the participating routers. If an active router fails a standby router can take over without a major
interruption in the host's connectivity.
HSRP runs on top of User Datagram Protocol (UDP), and uses port number 1985. Routers use their actual IP
address as the source address for protocol packets, not the virtual IP address, so that the HSRP routers can
identify each other.
Interface and Hardware Component Configuration Guide for Cisco NCS 6000 Series Routers, IOS XR Release 6.4.x
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Configuring Ethernet Interfaces