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--- network:extrawan [2010/11/09 13:51]
mats
+++ network:extrawan [2011/09/16 13:05] (current)
tibor
@@ Line 19: / Line 19: @@
 The VPI and VCI (VPI=Virtual Path Identifier, VCI=Virtual Channel Identifier) values must be set to unique values, or rather, there must not be two interfaces (rows) with the same combination of VPI and VCI. The VPI and VCI values together determine their channel identification in the ATM processing, in the central site modem (DSLAM) and further up the network. :!: As with almost all settings concerning Extra WAN interfaces, these values must be set by specification from the Internet service provider.
+{{:network:extrawan_adsl.jpg|}}
 ATM has the ability to specify resources on a per-PVC basis, thus using the bandwidth in an optimal way for different types of traffic, for example ensuring a minimal delay for certain critical traffic. The fields for setting these service parameters on the [[web_gui:extra_wan_interfaces|Extra WAN interfaces/ Virtual circuits]] page are ATM QoS class, PCR, SCR, BT and MBS. The ATM QoS class is by default set to UBR (Unspecified Bit Rate), implying that the traffic on this channel takes what bandwidth is available. One may think of UBR as the “best effort”. Other classes can be used to give traffic more priority. In particular, VBR-real time (VBR=Variable Bit Rate) is used for traffic sensitive to delays, for example voice streams. Further ATM settings that may be specified are:
@@ Line 33: / Line 35: @@
 Read more: [[wp>Asynchronous_Transfer_Mode|ATM]], [[wp>Permanent_virtual_circuit|PVC]], [[wp>Virtual_path_identifier|VPI]], [[wp>Virtual_channel_identifier|VCI]], [[wp>Traffic_contract|ATM traffic types]]
-===== Extra WAN interfaces in the ethernet case – VLAN tags =====
+===== Extra WAN interfaces in the Ethernet case – VLAN tags =====
 On the [[web_gui:network_page|Network Configuration]] web page, one may select to use “ET0” (on older 4-port models "ET4") as the WAN interface instead of “LINE”.
@@ Line 48: / Line 50: @@
 Many of the column headings are the same as for the ADSL case. In the Ethernet case, there is obviously no need for any ATM values.
 Instead, there is two columns to the far right of the page named //VLAN Id// and //PCP//.
-(IX68 and older versions of IX78 may not support the VLAN tagging, having no such column. One can also check the Help: Device Information from the top menu, under the “Hardware” box the switch chip type should be IP175D to support VLANs.)
+(older versions of Internet Gate may not support the VLAN tagging, having no such column. One can also check the Help: Device Information from the top menu, under the “Hardware” box the switch chip type should be IP175D to support VLANs.)
 The VLAN (Virtual LAN, Virtual Local Area Network) tagging according to specification IEEE Std 802.1Q is a way to let logical groups of stations communicate as if they were on the same LAN.
@@ Line 58: / Line 60: @@
 A mixture of tagged and non-tagged traffic on the WAN side is supported in only one special case: The use of a single non-VLAN-tagged channel along with one ore more tagged VLANs.
 The single non-VLAN-tagged interface should then be set to the (faked) //VLAN Id// “4096”.
+{{:network:extrawan_et0.jpg|}}
 One may also, for each VLAN used, fill in a //PCP// value. This is the three bit //Priority Code Point// value, sometimes called //CoS// (Class of Service), according to IEEE 802.1p standard.
@@ Line 173: / Line 177: @@
 ===== IGMP Proxy =====
-One of the WAN IP interfaces may be used for receiving multicast traffic, typically data streams for video and IP-TV.
+One of the WAN IP interfaces may be used for receiving [[multicast]] traffic, typically data streams for video and IP-TV.
 The task for a router is to distribute this traffic to whatever clients on the local side (LAN) that are listening.
 It is of course preferred not to send all multicast packets to all LAN clients at any time.
@@ Line 181: / Line 185: @@
 On the local side it acts as the ‘router’ that sends queries and keeps track of what hosts are members of which groups.
-The IGMP Proxy needs to know which is the upstream interface, i.e. from where it will expect incoming IGMP queries and to where it should send back reports of membership additions/removals in groups.
+The [[multicast|IGMP Proxy]] needs to know which is the upstream interface, i.e. from where it will expect incoming IGMP queries and to where it should send back reports of membership additions/removals in groups.
 Normally, when using only one WAN interface this is of course no problem.
 When using extra WAN interfaces, however, one must decide which of the multiple WAN “channels” that should be regarded as the upstream interface.

network/extrawan.1289307107.txt.gz · Last modified: 2010/11/09 13:51 by mats

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