EasyManuals Logo

Dell S4048T User Manual

Dell S4048T
1277 pages
To Next Page IconTo Next Page
To Next Page IconTo Next Page
To Previous Page IconTo Previous Page
To Previous Page IconTo Previous Page
Page #216 background imageLoading...
Page #216 background image
Multi-Exit Discriminators (MEDs)
If two ASs connect in more than one place, a multi-exit discriminator (MED) can be used to assign a
preference to a preferred path.
MED is one of the criteria used to determine the best path, so keep in mind that other criteria may impact
selection, as shown in the illustration in Best Path Selection Criteria.
One AS assigns the MED a value and the other AS uses that value to decide the preferred path. For this
example, assume the MED is the only attribute applied. In the following illustration, AS100 and AS200 connect
in two places. Each connection is a BGP session. AS200 sets the MED for its T1 exit point to 100 and the MED
for its OC3 exit point to 50. This sets up a path preference through the OC3 link. The MEDs are advertised to
AS100 routers so they know which is the preferred path.
MEDs are non-transitive attributes. If AS100 sends an MED to AS200, AS200 does not pass it on to AS300 or
AS400. The MED is a locally relevant attribute to the two participating ASs (AS100 and AS200).
NOTE: The MEDs are advertised across both links, so if a link goes down, AS 1 still has connectivity to
AS300 and AS400.
Figure 27. Multi-Exit Discriminators
NOTE: Configuring the set metric-type internal command in a route-map advertises the IGP cost
as MED to outbound EBGP peers when redistributing routes. The configured set metric value
overwrites the default IGP cost. If the outbound route-map uses MED, it overwrites IGP MED.
Border Gateway Protocol IPv4 (BGPv4) 216

Table of Contents

Questions and Answers:

Question and Answer IconNeed help?

Do you have a question about the Dell S4048T and is the answer not in the manual?

Dell S4048T Specifications

General IconGeneral
Switching Capacity1.44 Tbps
Rack Units1U
Form FactorRack-mountable
Power DeviceInternal power supply
Power RedundancyOptional
Product TypeSwitch
Jumbo Frame SupportYes
Routing ProtocolOSPF, BGP, RIP, VRRP, PIM-SM, IGMP
Remote Management ProtocolSNMP, RMON, Telnet, SSH
FeaturesQuality of Service (QoS), Jumbo Frames Support, Virtual Route Redundancy Protocol (VRRP), VLAN support, sFlow, Multiple Spanning Tree Protocol (MSTP), Rapid Spanning Tree Protocol (RSTP), IPv6 support
Compliant StandardsIEEE 802.3, IEEE 802.3u, IEEE 802.3ab, IEEE 802.3ae
Dimensions (W x D x H)17.3 in x 16 in x 1.7 in
Operating Temperature0°C to 40 °C
Operating Humidity10% to 90% (non-condensing)

Related product manuals