Figure 21. BGP Local Preference
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
.
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.
174
Border Gateway Protocol IPv4 (BGPv4)
Содержание S3048-ON
Страница 1: ...Dell Configuration Guide for the S3048 ON System 9 11 2 5 ...
Страница 137: ...0 Gi 1 1 Gi 1 2 rx Flow N A N A 0 0 No N A N A yes Access Control Lists ACLs 137 ...
Страница 142: ...Figure 10 BFD Three Way Handshake State Changes 142 Bidirectional Forwarding Detection BFD ...
Страница 241: ...Dell Control Plane Policing CoPP 241 ...
Страница 287: ... RPM Synchronization GARP VLAN Registration Protocol GVRP 287 ...
Страница 428: ...Figure 53 Inspecting the LAG Configuration 428 Link Aggregation Control Protocol LACP ...
Страница 429: ...Figure 54 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 429 ...
Страница 432: ...Figure 56 Inspecting a LAG Port on BRAVO Using the show interface Command 432 Link Aggregation Control Protocol LACP ...
Страница 433: ...Figure 57 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 433 ...
Страница 477: ...Figure 73 Configuring Interfaces for MSDP Multicast Source Discovery Protocol MSDP 477 ...
Страница 478: ...Figure 74 Configuring OSPF and BGP for MSDP 478 Multicast Source Discovery Protocol MSDP ...
Страница 479: ...Figure 75 Configuring PIM in Multiple Routing Domains Multicast Source Discovery Protocol MSDP 479 ...
Страница 483: ...Figure 77 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 483 ...
Страница 484: ...Figure 78 MSDP Default Peer Scenario 3 484 Multicast Source Discovery Protocol MSDP ...
Страница 634: ...protocol spanning tree pvst no disable vlan 300 bridge priority 4096 634 Per VLAN Spanning Tree Plus PVST ...
Страница 745: ...Figure 104 Single and Double Tag TPID Match Service Provider Bridging 745 ...
Страница 746: ...Figure 105 Single and Double Tag First byte TPID Match 746 Service Provider Bridging ...