Allied-telesis AT-S62 Manuel d'utilisateur Page 544

  • Télécharger
  • Ajouter à mon manuel
  • Imprimer
  • Page
    / 760
  • Table des matières
  • DEPANNAGE
  • MARQUE LIVRES
  • Noté. / 5. Basé sur avis des utilisateurs
Vue de la page 543
Chapter 25: Tagged and Port-based Virtual LANs
Section V: Virtual LANs 544
Enabling or Disabling Ingress Filtering
There are rules a switch follows when it receives and forwards an
Ethernet frame. There are rules for frames as they enter a port (called
ingress rules) and rules for when a frame is transmitted out a port (called
egress rules). A switch does not accept and forward a frame unless the
frame passes the ingress and egress rules.
There are quite a few ingress and egress rules for Fast Ethernet switches.
Fortunately, this discussion need only review the rules as they apply to
tagged frames, because ingress filtering does not apply to untagged
frames.
First, as a reminder, a tagged frame is an Ethernet frame that contains a
tagged header. The header contains the VID of the VLAN to which the
frame originated. For further information, refer to Tagged VLAN
Overview on page 523.
The ingress rules are applied to tagged frames when ingress filtering is
activated. The switch examines the tagged header of each tagged frame
that enters a port and determines whether the tagged frame and the
port that received the frame are members of the same VLAN. If they
belong to the same VLAN, the port accepts the frame. If they belong to
different VLANs, the port discards the frame.
As an example, assume that a tagged frame with a VID of 4 is received on
a port that is a member of a VLAN also with a VID of 4. In this case, the
port accepts the frame, because both the frame and the port belong to
the same VLAN. If the frame and port belong to different VLANs, the
frame is discarded.
How do the egress rules apply when ingress filtering is disabled? First,
any tagged frame is accepted on any port on the switch. It does not
matter whether the frame and the port belong to the same or different
VLANs.
After the tagged frame is received, the switch examines the tagged
header and determines if the VID in the header corresponds to any
VLANs on the switch. If there is no corresponding VLAN, the switch
discards the frame. If there is, the switch transmits the frame out the port
to the destination node, assuming that the destination node’s MAC
address is in the MAC address table, or floods the port to all ports on the
VLAN if the MAC address is not in the table.
In addition, each tagged frame contains a priority tag that informs the
switch about the importance of the frame. Frames with a high priority
are handled ahead of frames with a low priority.
Vue de la page 543
1 2 ... 539 540 541 542 543 544 545 546 547 548 549 ... 759 760

Commentaires sur ces manuels

Pas de commentaire

Audyssey Odbiornik podręczniki użytkownika

Lista Audyssey Odbiornik produkty zawierają 1 instrukcje obsługi do modeli 1. Wszystkie podręczniki użytkownika w formacie pdf są dostępne do pobrania lub obejrzenia online.

Kliknij na poniższy alfabet, aby przejść do pełnej listy modeli zaczynających się od tej litery

Modele Rodzaj dokumentu
MultEQ Pro
Podręcznik Użytkownika   Audyssey MultEQ Pro User guide, 46 strony