Extreme Networks ExtremeWare XOS Guide Manual page 646

Glossary
A (Continued)
autobind
autonegotation
B
backbone area
backup port
backup router
BDR
BGP
bi-directional rate shaping
ExtremeWare XOS 11.3 Concepts Guide
In STP, autobind, when enabled, automatically adds or removes ports
from the STPD. If ports are added to the carrier VLAN, the member
ports of the VLAN are automatically added to the STPD. If ports are
removed from the carrier VLAN, those ports are also removed from
the STPD.
As set forth in IEEE 802.3u, autonegotation allows each port on the
switch—in partnership with its link partner—to select the highest
speed between 10 Mbps and 100 Mbps and the best duplex mode.
In OSPF, a network that has more than one area must have a
backbone area, configured as 0.0.0.0. All areas in an AS must connect
to the backbone area.
In RSTP, the backup port supports the designated port on the same
attached LAN segment. Backup ports exist only when the bridge is
connected as a self-loop or to a shared media segment.
In VRRP, the backup router is any VRRP router in the VRRP virtual
router that is not elected as the master. The backup router is available
to assume forwarding responsibility if the master becomes
unavailable.
Backup designated router. In OSPF, the system elects a DR and a BDR.
The BDR smooths the transition to the DR, and each multiaccess
network has a BDR. The BDR is adjacent to all routers on the network
and becomes the DR when the previous DR fails. The period of
disruption in transit traffic lasts only as long as it takes to flood the
new LSAs (which announce the new DR). The BDR is elected by the
protocol; each hello packet has a field that specifies the BDR for the
network.
Border Gateway Protocol. BGP is a router protocol in the IP suite
designed to exchange network reachability information with BGP
systems in other ASs. You use a fully meshed configuration with BGP.
BGP provides routing updates that include a network number, a list of
ASs that the routing information passed through, and a list of other
path attributes. BGP works with cost metrics to choose the best
available path; it sends updated router information only when one
host has detected a change, and only the affected part of the routing
table is sent. BGP communicates within one AS using Interior BGP
(IBGP) because BGP does not work well with IGP. The routers inside
the AS thus maintain two routing tables: one for the IGP and one for
IBGP. BGP uses exterior BGP (EBGP) between different ASs.
This is a hardware-based technology that allows you to manage
bandwidth on Layer 2 and Layer 3 traffic flowing to each port on the
switch and to the backplane, per physical port on the I/O module.
The parameters differ across platforms and modules.
646