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Dec 07, 2022 407 likes •554 views

RBridge Aggregation Mingui Zhang, Donald Eastlake zhangmingui@huawei.com RBridge Aggregation 1 Single AF: Loop Avoidance To avoid loops involving native frames, TRILL allows only a single Appointed Forwarder for one VLAN on a local link.

SLIDE 1

RBridge Aggregation

Mingui Zhang, Donald Eastlake zhangmingui@huawei.com

1 RBridge Aggregation

SLIDE 2

Single AF: Loop Avoidance

To avoid loops involving native frames, TRILL

allows only a single Appointed Forwarder for

ne VLAN on a local link.
RB2

RB1

Local Link Local Link

Single AF means single ingress & single egress

for a specific VLAN.

2 RBridge Aggregation

VLAN-x

SLIDE 3

Purpose of Aggregation

Provide active/active multi-homing to a

specific VLAN on a local link

Increase the reliability of TRILL edge
Increase the access bandwidth of RBridge

campus

3 RBridge Aggregation

SLIDE 4

RBridge Aggregation

Two RBridges use one

nickname, pseudonode nickname, to ingress frames.

Transit RBridge Campus

RBi

Transit RBridge Campus

RBi

Advertise virtual links

(e.g., RB1-RBv, RB2-RBv)

They can forward data

frame for VLAN-x at the same time (active-active).

4 RBridge Aggregation

VLAN-x

RB1 RB2 RB1 RB2

VLAN-x

RBv B1 B1

SLIDE 5

Two Possible Issues

Traffic Duplication

– Multicast frames egressed by both aggregated members

Transit RBridge Campus Transit RBridge Campus

Forwarding Loop

– Multicast frames from the local link are egressed back to the local link by another aggregated member

RBridge Aggregation 5 RB1 RB2 RBv RB1 RB2 RBv

Traffic Duplication Forwarding Loop

B1 B1

SLIDE 6

Link Aggregation [802.1AX] or Hashing

The access links of the bridge are configured

as link aggregation [802.1AX].

– A frame is transmitted by one link one time

Choose a single member using local hashing

– A frame goes through one RBridge one time – Current version of our draft adopt this solution

6 RBridge Aggregation

SLIDE 7

Frame Processing: Known Unicast

Ingress

– Set the nickname to the pseudonoe nickname “RBv” – Receiver ingresses the frame to the TRILL campus

Egress

– Receiver egresses the frame to the local link

7 RBridge Aggregation

Only once Only once

SLIDE 8

Frame Processing: Multicast

Ingress

– If hashing matches

Set the nickname to “RBv” and send it

– If not, drop it

Only once

– If not, drop it

Egress

– If hashing matches

send the frame

– If not, drop it

8 RBridge Aggregation

Only once

SLIDE 9

Frame Processing: Unknown Unicast

Ingress

– The access bridge sends one copy of the frame with unknown unicast blocking technique – Aggregated RBridges treat the frame as unicast – Aggregated RBridges treat the frame as unicast

Egress

– Same as multicast egress

9 RBridge Aggregation

Only once Only once

SLIDE 10

MAC Learning

MAC addresses of the aggregated RBridges

SHOULD be synchronized using ESADI.

Before a MAC address is got from another

aggregation member’s ESADI, frames destined to this MAC address will be sent as unknown unicast.

10 RBridge Aggregation

SLIDE 11

Hashing Function Configuration

An aggregation member can only send

multicast frames with a specific hashing value.

– E.g., RB1 only sends multicast frames that the last bit of their source MAC is “0”. bit of their source MAC is “0”.

RBridge Aggregation 11

SLIDE 12

Hashing under Link Failures

When a connection to one aggregation

member failed, the next member on the list takes the responsibility to send multicast frames for the aggregation. frames for the aggregation.

RBridge Aggregation 12

SLIDE 13

Thanks!

13 RBridge Aggregation