MAC Access List EtherType

When configuring MAC Access Lists, it is possible to filter out frames based on the value found in the EtherType field of the Ethernet frame. However, depending upon the IOS version and the platform being used, you may find that there is a limitation as to what EtherTypes can be filtered.

On some platforms, it is possible to specify any value for the EtherType. On others, only specific values are allowed.

For example, examine this context sensitive help:

SW1(config)#mac access-list extended NO-IPV6
SW1(config-ext-macl)#permit any any ?
  <0-65535>        An arbitrary EtherType in decimal or hex
  aarp             EtherType: AppleTalk ARP
  amber            EtherType: DEC-Amber
  appletalk        EtherType: AppleTalk/EtherTalk
  cos              CoS value
  dec-spanning     EtherType: DEC-Spanning-Tree
  decnet-iv        EtherType: DECnet Phase IV
  diagnostic       EtherType: DEC-Diagnostic
  dsm              EtherType: DEC-DSM
  etype-6000       EtherType: 0x6000
  etype-8042       EtherType: 0x8042
  lat              EtherType: DEC-LAT
  lavc-sca         EtherType: DEC-LAVC-SCA
  lsap             LSAP value
  mop-console      EtherType: DEC-MOP Remote Console
  mop-dump         EtherType: DEC-MOP Dump
  msdos            EtherType: DEC-MSDOS
  mumps            EtherType: DEC-MUMPS
  netbios          EtherType: DEC-NETBIOS
  protocol-family  An Ethernet protocol family
  vines-echo       EtherType: VINES Echo
  vines-ip         EtherType: VINES IP
  vlan             Vlan Id
  xns-idp          EtherType: XNS IDP

Notice that there are many options that can be chosen using keywords that refer to specific EtherType values. However, you are also given the option (stated on the first line) of an arbitrary EtherType in decimal or hex. So any value can be applied.

On other platforms, you may see something like this:

SW1(config)#mac access-list extended NO-IPV6
SW1(config-ext-macl)#permit any any ?
  aarp          EtherType: AppleTalk ARP
  amber         EtherType: DEC-Amber
  appletalk     EtherType: AppleTalk/EtherTalk
  dec-spanning  EtherType: DEC-Spanning-Tree
  decnet-iv     EtherType: DECnet Phase IV
  diagnostic    EtherType: DEC-Diagnostic
  dsm           EtherType: DEC-DSM
  etype-6000    EtherType: 0x6000
  etype-8042    EtherType: 0x8042
  lat           EtherType: DEC-LAT
  lavc-sca      EtherType: DEC-LAVC-SCA
  mop-console   EtherType: DEC-MOP Remote Console
  mop-dump      EtherType: DEC-MOP Dump
  msdos         EtherType: DEC-MSDOS
  mumps         EtherType: DEC-MUMPS
  netbios       EtherType: DEC-NETBIOS
  vines-echo    EtherType: VINES Echo
  vines-ip      EtherType: VINES IP
  xns-idp       EtherType: XNS IDP
  

SW1(config-ext-macl)#permit any any

Notice here that the option of an arbitrary EtherType value is not given. Only the specified EtherTypes can be configured. Depending on the platform you are using you will be given varying options.

Links:

https://forum.networklessons.com/t/vlan-access-list-vacl/1155/59?u=lagapidis

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/security/m1/sec-m1-cr-book/sec-cr-p1.html#wp4193720440